TM 1--1520--264--23

TECHNICAL MANUAL

AVIATION UNIT MAINTENANCE (AVUM)

AND AVIATION INTERMEDIATE

MAINTENANCE (AVIM)

MANUAL

NONDESTRUCTIVE INSPECTION PROCEDURES

FOR

AH--64 HELICOPTER SERIES

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

HEADQUARTERS, DEPARTMENT OF THE ARMY

30 NOVEMBER 1996
 TM 1-1520-264-23

 C1

Change HEADQUARTERS

 DEPARTMENT OF THE ARMY

NO. 1 WASHINGTON, D. C., 30 March 2000

AVIATION UNIT MAINTENANCE (AVUM) AND

AVIATION INTERMEDIATE MAINTENANCE (AVIM)

MANUAL

NONDESTRUCTIVE PROCEDURES

FOR

AH-64 HELICOPTER SERIES

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

TM 1-1520-264-23, 30 November 1996, is changed as follows.

1. Remove and insert pages as indicated below. New or changed text material is indicated by

a vertical bar in the margin. An illustration change is indicated by a miniature pointing hand

Remove pages Insert pages

Cover

iii and iv

Cover

A/(B blank)

iii and iv

2-38-1 through 2-38.8 blank

2-71 through 2-74 blank

2. Retain this sheet in front of the manual for reference purpose.
TM 1-1520-264-23 C1

By Order of the Secretary of the Army:

Official: ERIC K. SHINSEKI

 

 General, United States Army 

 Chief of Staff

 JOEL B. HUDSON

Administrative Assistant to the 

 Secretary of the Army

 9934002

Distribution:

To be distributed in accordance with Initial Distribution Number (IDN) 313681

requirements for TM 1-1520-264-23.

 
TM 1-1520-264-23

WARNING SUMMARY

Personnel performing inspections involving operations, procedures, and practices, which are included or implied in this

technical manual, shall observe the following instructions.

Highlights an operation, procedure, practice, condition, statement, etc., if not strictly

observed, could result in injury to, or death of, personnel.

CAUTION

Highlights an operation, procedure, practice, condition, statement, etc., if not strictly

observed, could result in damage to or destruction of equipment or loss of mission

effectiveness.

NOTE

Highlights an essential operation, procedure, condition, or statement.

The following are general safety precautions that are not related to any specific procedures and, therefore do not appear

elsewhere in this publication. These are recommended precautions that personnel must understand and apply during

many phases of nondestructive inspections.

GENERAL

Assure compliance with safety requirements in Technical Manual, Nondestructive Inspection Methods, TM 55-1500-335-

23.

Assure compliance with the safety and precautionary measures addressed in the applicable technical manuals listed in

Table 1-1. Refer to these manuals for detailed information relating to safety considerations for the specific area or

system on which the nondestructive inspection procedure is to be performed.

Aircraft Grounding

All aircraft shall be grounded in accordance with FM 55-41 at all times.

a
TM 1-1520-264-23

Electrical Hazard

Assure that all safety precautions for using electrical equipment near aircraft fuel cells,

oxygen systems, and stores have been met.

Solvents

Most solvents are flammable. Keep away from heat and open flame. Vapors may be

harmful. Use with adequate ventilation. Avoid prolonged or repeated breathing of

vapor. Avoid contact with skin and eyes. Do not take internally. Comply with pollution

control rules concerning photochemically reactive solvents.

Keep Away From Live Circuits

Inspection personnel must at all times observe all safety regulations. Do not replace

components or make adjustments inside equipment with a high voltage supply turned on.

Under certain conditions, dangerous potentials may exist even when the power control is

in the off position, due to charges retained by capacitors. To avoid injuries, always

remove power. Discharge and ground a circuit before touching it. Make sure that

equipment is grounded to same earth ground as aircraft.

Electrical and Electronic Equipment

Do not wear rings, watches, or metal jewelry when working around electrical equipment.

RESUSCITATION

Personnel working with or near high voltages should be familiar with modern methods of resuscitation. Such information

may be obtained from the Office of Bioenvironment Health or is listed in FM 21-11.

b
TM 1-1520-264-23

Cleaning Solvents

* Those areas where skin and clothing come in contact with cleaning solvents should be washed 

thoroughly and immediately after contact.

* Saturated clothing should be removed immediately.

* Areas where cleaning solvents are used should be adequately ventilated to keep vapors to a 

minimum.

* In case of contact with eyes, nose, or ears, flush them with generous quantities of water and then 

seek medical attention immediately.

Foreign Object Damage

* Make sure area is clear of foreign objects before closing access doors, panels, and fairings.

* If area is not clear, damage to components or systems could result in personal injury or death.

Lifting Components with Hoist

* Lifting or hoisting of components shall be done only by designated personnel.

* Before lifting, alert personnel in immediate areas.

* Before lifting, balance the load.

* Do not stand under load while it is being moved from one area to another on a hoist.

* Do not stand under load to do inspection work.

Compressed Air

* Do not use more than 30 PSIG compressed air for cleaning purposes.

* Use eye protection to prevent injury to personnel.

c
TM 1-1520-264-23

The following are warnings and cautions related to specific procedures that appear elsewhere in this publication. These

are precautions that personnel must understand and apply during nondestructive inspections.

To prevent injury to personnel and damage to helicopter, stand only on designated surfaces.

These areas are reinforced to withstand frequent use and are treaded to prevent slipping. All

other surfaces are NO STEP areas.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands and

restraint equipment when working above 10 feet on helicopter in a nontactical environment.

Otherwise, personnel injury could result from accidental falls.

Cleaning solvents P-D-680, Type II and MIL-C-38736 are flammable. Avoid eye and skin

contact or breathing vapors. Protective equipment consisting of goggles, gloves, and respiratory

protection is required.

Electrical equipment shall not be operated in areas where combustible gases or vapors may be

present, unless the equipment is explosion proof.

* Black lights generate considerable heat during use. Extreme care must be exercised to 

prevent contacting the housing with any part of the body.

* To prevent injury to eyes, do not look directly into black light.

* Prolonged direct exposure of hands to the filtered black light's main beam may be 

harmful. Suitable gloves shall be worn when exposing hands to the main beam.

d
TM 1-1520-264-23

Prolonged or repeated inhalation of vapors or powders may result in irritation of mucous

membrane areas of the nose.

Continual exposure to penetrant inspection material may cause skin irritation.

Temperatures in excess of 49°C (120°F) may cause bursting of pressurized cans and

injury to personnel.

Volatile fumes may occur, creating both a fire and health hazard.

Prolonged breathing of vapor from organic solvents, degreasers, or paint thinners is

dangerous. Use respirators in confined areas per Occupational and Environmental

Health Respiratory Protection Program (TB MED 502 (DLAM 1000.2)). Have adequate

ventilation. Avoid prolonged skin contact. Wear rubber gloves and goggles.

Radiation Hazard

Assure compliance with all applicable safety precautions set forth in TM 55-1500-335-23

(Nondestructive Inspection Methods manual). A hazard associated with exposure to

ionizing radiation is that serious injury can be inflicted without pain, burning, or other

sense of discomfort during the exposure period. Radiation protection shall be utilized in

accordance with AR40-14/DLAR 1000.28.

e
TM 1-1520-264-23

CAUTION

Do not use cleaning solvent MIL-C-38736 on acrylic lacquer, as it may soften finish.

CAUTION

Penetrant-Emulsifier/Remover Combinations (lipophillic/hydrophilic) from one

manufacturer may not be mixed or used in conjunction with materials from a different

manufacturer.

CAUTION

Do not operate magnetic particle equipment within 36 inches of aircraft instruments.

CAUTION

Misinterpretation of indications can result in rejectable parts being accepted and

acceptable parts being rejected. Only NDI personnel trained and qualified in accordance

with applicable military standards and technical manuals shall perform and interpret

nondestructive inspections.

CAUTION

Exercise extreme caution when handling and inspecting the drive shaft assemblies. The

assembly may be rendered unserviceable by even slight dents or scratches.

f
 TM 1-1520-264-23

 Change 1 A/B blank)

LIST OF EFFECTIVE PAGES

Insert latest changed pages; dispose of superseded pages in accordance with regulations.

NOTE: On a changed page, the portion of the text affected by the latest change is indicated by

a vertical line, or other change symbol, in the outer margin of the page. Changes to illustrations

are indicated by miniature pointing hands. Changes to wiring diagrams are indicatd by shaded

areas.

Dates of issue for origional and changed pages are:

Origional -30 November 1996

Change 1 -30 March 2000

Page Change

No. No.

Page Change

No. No.

Cover .....................................................1

a - f .........................................................0

A .............................................................1

B blank ..................................................0

i ii ...........................................................0

iii ..............................................................1

iv –xiv blank ........................................0

1-1 – 1-46 blank .................................0

2-1 –2-38 ..............................................0

2-38.1 – 2-38.8 blank .......................1

2-39 – 2-70 ....................................0

2-71 – 2-74 blank .......................1

3-1 – 3-62 ........................... ........0

4-1 – 4-86 ......................................0

5-1 – 5-22 blank ...........................0

6-1 – 6-90 ......................................0

A-1 – A-10 blank .........................0

B-1 – B-4 ........................................0

C-1 – C-2 ........................................0

Index 1 – Index 22 ......................0
TM 1-1520-264-23

TECHNICAL MANUAL HEADQUARTERS

DEPARTMENT OF THE ARMY

No. 1-1520-264-23 Washington, D.C. 30 November 1996

Aviation Unit Maintenance (AVUM) and Aviation Intermediate Maintenance (AVIM) Manual Nondestructive

Inspection Procedures

for

AH-64A Helicopter

REPORTING OF ERRORS AND RECOMMENDING IMPROVEMENTS

You can help improve this manual. If you find any mistakes or if you know of a way to improve the procedures, please

let us know. Mail your letter, DA Form 2028 (Recommended Changes to Publications and Blank Forms), or DA Form

2028-2 located in back of this manual direct to: Commander, U.S. Army Aviation and Troop Command, ATTN:

AMSAT-I-MP, 4300 Goodfellow Boulevard, St. Louis, MO 63120-1798. A reply will be furnished to you.

DISTRIBUTION STATEMENT A Approved for Public Release; Distribution Unlimited

TABLE OF CONTENTS

Section/Paragraph Page

WARNING SUMMARY .............................................................. ................................................... a

LIST OF ILLUSTRATIONS ........................................................................................................... viii

LIST OF TABLES ......................................................................................................................... xiii

I. INTRODUCTION ....................................................................... ............................................. 1-1

1.1 GENERAL INFORMATION ................................................ .................................. 1-2

1.1.1 Special Terms, Abbreviations, and Acronyms ...................................................... 1-4

1.1.2 How to Use This Manual ............................................. ......................................... 1-5

1.1.3 Inspection Item Code ................................................ ........................................... 1-6

1.1.4 Use of NDI Symbols ............................................................................................. 1-6

1.1.5 Use of Reference Publications ........................................ ..................................... 1-6

1.1.6 Related Publications ................................................. ........................................... 1-6

1.1.7 Description............................................................................................................ 1-6

1.1.8 Configuration ................................................. ...................................................... 1-8

1.1.9 Airframe Stations ................................................... .............................................. 1-8

1.2 TYPE OF CONSTRUCTION .......................................... ...................................... 1-8

1.2.1 Rotor System ....................................................... ................................................ 1-8

1.2.2 Drive System ................................................ ....................................................... 1-12

1.2.3 Airframe and Landing Gear System ................................... ................................. 1-12

1.2.4 Engine System ..................................................................................................... 1-13

i
TM 1-1520-264-23

TABLE OF CONTENTS - Continued

Section/Paragraph Page

1.2.5 Flight Control System ............................................................................................... 1-13

1.2.6 Access Provisions ................................................... ................................................. 1-13

1.2.7 Steps, Handholds, and Walkways ............................................................................. 1-13

1.3 MARKING AND/OR RECORDING OF INSPECTION RESULTS .............................. 1-21

1.4 NONDESTRUCTIVE INSPECTION METHODS ....................................................... 1-22

1.4.1 Purpose of Nondestructive Inspection (NDI) ............................................................. 1-22

1.4.2 Selecting the NDI Method ............... .............................. ......................................... 1-23

1.4.3 Preparation of Helicopter for NDI ...................................... ....................................... 1-23

1.4.4 Preparation of Part or Area for NDI .................................... ...................................... 1-23

1.4.5 NDI General Safety Precautions ............................................................................... 1-24

1.4.6 Bond Testing (BT) Method ............................................ ........................................... 1-24

1.4.6.1 Bond Testing Equipment ............................................. ............................................. 1-24

1.4.6.2 Safety Precautions During Bond Testing ............................... ................................... 1-26

1.4.7 Fluorescent Penetrant (PT) Method ......................................................................... 1-26

1.4.7.1 Safety Precautions During Fluorescent Penetrant Inspection .................................... 1-27

1.4.7.2 Controlling Excess Fluorescent Penetrant .............................. .................................. 1-32

1.4.8 Magnetic Particle (MT) Method ....................................... ......................................... 1-32

1.4.8.1 Magnetic Particle Inspection Equipment ................................................................... 1-32

1.4.8.1.1 Magnetic Yokes and Probes ..................................................................................... 1-34

1.4.8.1.2 Hand-held Coil ...................................................... ................................................... 1-34

1.4.8.2 Safety Precautions During Magnetic Particle Inspections ................. ........................ 1-34

1.4.9 Demagnetization of Inspection Parts ................................... ..................................... 1-34

1.4.9.1 Demagnetization Using AC ........................................... ........................................... 1-35

1.4.9.2 Demagnetization Using DC ........................................... ........................................... 1-35

1.4.10 Radiographic (RT) Method ............................................ ........................................... 1-35

1.4.10.1 Safety Precautions During Radiographic Inspections ................................................ 1-35

1.4.10.2 Mixing of Radiographic Film Processing Chemicals ...................... ........................... 1-36

1.4.11 Eddy Current (ET) Method ........................................... ............................................ 1-36

1.4.11.1 Safety Precautions During Eddy Current Inspection ...................... ........................... 1-37

1.4.11.2 Eddy Current Scanning Techniques ................................... ..................................... 1-37

1.4.11.2.1 Scanning Around Fasteners, Inserts, and Edges of Parts ................. ........................ 1-37

1.4.11.2.2 Bolthole Inspection ................................................................................................... 1-37

1.4.11.2.3 Scanning Fillets and Radii ........................................................................................ 1-37

1.4.11.3 Eddy Current Instrument Standardization ............................... .................................. 1-38

1.4.11.4 Sorting Metal Using Eddy Current ..................................... ....................................... 1-38

1.4.12 Ultrasonic (UT) Method .............................................. .............................................. 1-38

1.4.12.1 Safety Precautions During Ultrasonic Inspection ......................... ............................. 1-38

1.4.12.2 Ultrasonic Instrument Standardization ................................. ..................................... 1-40

1.4.13 Acceptance/Rejection Criteria ........................................ .......................................... 1-41

ii
 TM 1-1520-264-23

 Change 1 iii

TABLE OF CONTENTS – Continued

Section/Paragraph.........................................................................................................................Page

1.4.14 Equipment Used for NDI...........................................................................1-41

1.4.15 Materials Used for NDI..............................................................................1-41

1.4.16 Post Cleaning and Restoration of Part or Area After NDI...........1-41

II ROTOR SYSTEM .................................................................................................................2-1

2.1 CONTENTS ....................................................................................... ...........2-1

2.2 MAIN ROTOR DROOP STOP FOLLOWER (PLUNGER) (PT) ...2-5

2.3 DROOP STOP RING(MT) ..........................................................................2-5

2.4 MAIN ROTOR BLADE (VOIDS) (BT) ...................................................2-9

2.5 MAIN ROTOR BLADE (PT) ......................................................................2-12

2.6 MAIN ROTOR BLADE (RT) .....................................................................2-13

2.7 MAIN ROTOR BLADE WEIGHT SUPPORT FITTINGS (ET) .....2-17

2.8 MAIN ROTOR MAST (MT) ........................................................................2-19

2.9 MAIN ROTOR MAST RETAINING RING (MT) ...............................2-20

2.10 MAIN ROTOR HUB RETENTION NUT (MT) ..................................2-23

2.11 MAIN ROTOR HEAD (HUB) (ET) ..........................................................2-25

2.12 MAIN ROTOR LEAD LAG LINK (DAMPER LINK) (ET) ...............2-27

2.13 MAIN ROTOR DAMPER (ET) ..................................................................2-30

2.14 MAIN ROTOR DAMPER TRUNION (ET) .........................................2-31

2.15 MAIN ROTOR DAMPER ROD END (MT) ........................................2-35

2.16 MAIN ROTOR PITCH HOUSING (ET) ..............................................2-37

2.16.1.1 STRAP PACK OUTBOARD BOLT INSPECTION (UT) .............2-38.1

2.17 MAIN ROTOR FEATHERING BEARING HOUSING (ET) ...........2-40

2.18 MAIN ROTOR STRIKER PLATE AND SHIMS (MT) ..................2-41

2.19 MAIN ROTOR HUB BEARING (ET) ...................................................2-45

2.20 MAIN ROTOR LOWER SHOE (ET) ......................................................2-46

2.21 MAIN ROTOR HEAD HUB LOAD PLATE (MT) ............................2-49

2.22 MAIN ROTOR HUB BRACKETS (MT) ................................................2-51

2.23 MAIN ROTOR HUB LOWER PLATE (MT) ........................................2-52

2.24 TAIL ROTOR FORK ASSEMBLY(HEAD AND TEETER STOP)..2-54

2.25 TAIL ROTOR BLADE (PT) ........................................................................2-57

2.26 TAIL ROTOR BLADE (VOIDS) (BT) ......................................................2-58

2.27 TAIL ROTOR BLADES (FLUID) (RT) .......................................................2-61

2.28 TAIL ROTOR HUB (ET) ................................................................................2-65

2.29 TAIL ROTOR CLAMPS AND LOCKING PLATES (ET) .................2-66

III DRIVE SYSTEM ......... ..............................................................................................................3-1

3.1 CONTENTS ........................................................................................................3-1

3.2 DRIVE SHAFTS (ET) ...................................................................................3-4

3.3 DRIVETRAIN COUPLINGS (ET) .............................................................3-7
TM 1-1520-264-23

TABLE OF CONTENTS - Continued

Section/Paragraph Page

3.4 DRIVETRAIN FLANGES (MT) ........................................ ......................................... 3-8

3.5 DAMPER AND ANTI-FLAIL SUPPORTS (ET) ........................... .............................. 3-11

3.6 FORWARD HANGER BEARING FLANGE (MT) ...................................................... 3-13

3.7 FORWARD HANGER BEARING SUPPORT (ET) .................................................... 3-15

3.8 AFT HANGER BEARING FLANGE (MT) .................................................................. 3-17

3.9 AFT HANGER BEARING SUPPORT (ET) .............................. ................................. 3-18

3.10 INTERMEDIATE GEARBOX CENTRIFUGAL FAN (ET) .................. ........................ 3-22

3.11 ENGINE NOSE GEARBOX (ET) .............................................................................. 3-25

3.12 ENGINE NOSE GEARBOX INPUT QUILL SHAFT (MT) .................. ........................ 3-26

3.13 MAIN TRANSMISSION (ET) .......................................... .......................................... 3-29

3.14 MAIN TRANSMISSION COMPRESSOR DRIVE ADAPTER (ET) ............................. 3-32

3.15 MAIN TRANSMISSION APU DRIVE FLANGE (MT) ................................................. 3-33

3.16 MAIN TRANSMISSION TAIL ROTOR DRIVE FLANGE (MT) ................................... 3-36

3.17 MAIN ROTOR GEARSHAFT DRIVE GEAR TEETH (MT) .'................ ..................... 3-38

3.18 MAIN ROTOR MAST SUPPORT BASE (ET) ........................... ................................ 3-40

3.19 INTERMEDIATE GEARBOX (ET) ..................................... ....................................... 3-42

3.20 INTERMEDIATE GEARBOX RETAINERS (ET) ......................... .............................. 3-45

3.21 INTERMEDIATE GEARBOX FLANGE AND SHOULDERED SHAFT (MT)................ 3-48

3.22 TAIL ROTOR GEARBOX (ET) ........................................ ......................................... 3-49

3.23 TAIL ROTOR GEARBOX SHOULDERED SHAFT (MT) ........................................... 3-51

3.24 TAIL ROTOR GEARBOX RETAINERS (ET) ............................ ................................ 3-54

3.25 TAIL ROTOR GEARBOX FORWARD AND AFT STRUT (MT) ................................. 3-56

3.26 TAIL ROTOR GEARBOX FORWARD AND AFT STRUT FITTINGS (MT) ................ 3-59

3.27 MAIN ROTOR HEAD (HUB) (ET) ................................... ........................................ 3-62

3.28 MAIN ROTOR SUPPORT MAST (MT) ..................................................................... 3-62

IV AIRFRAME AND LANDING GEAR SYSTEM .............................................................................. 4-1

4.1 CONTENTS ....................................................... ...................................................... 4-1

4.2 FUSELAGE AND EMPENNAGE ACCESS DOORS, COVERS, PANELS,

SKINS, AND FAIRINGS- METAL (ET) ............................... ...................................... 4-5

4.3 HONEYCOMB CORE FUSELAGE PANELS, VERTICAL FIN, ETC. (BT) ... ............ 4-6

4.4 FLUID IN HONEYCOMB CORE FUSELAGE PANELS, VERTICAL FIN,

ETC. (RT) ................................................................................................................ 4-10

4.5 FITTINGS, CASTINGS, AND FORGINGS (ET) ......................... .............................. 4-14

4.6 TRANSMISSION DECK (ET) ......................................... .......................................... 4-16

4.7 EMPENNAGE FRAME ASSEMBLIES F.S. 530 AND F.S. 547 AND

ATTACHED STRINGERS (ET) ...................................... .......................................... 4-18

4.8 FUSELAGE SUPPORT HOLES (ET) .................................. ..................................... 4-21

4.9 GUN AND AMMO SUPPORT MOUNT PADS (ET) ...................... ............................ 4-22

4.10 MAIN LANDING GEAR SHOCK STRUT SUPPORT (MT) ........................................ 4-26

iv
TM 1-1520-264-23

TABLE OF CONTENTS - Continued

Section/Paragraph Page

4.11 MAIN LANDING GEAR CROSS TUBE MOUNTING POINTS (ET) ......... ................. 4-27

4.12 ROTOR SUPPORT MIXER ASSEMBLY AND MOUNTING

SURFACES (MT) ..................................................................................................... 4-29

4.13 ROTOR MIXER SUPPORT ASSEMBLY BOLT (MT) ..................... .......................... 4-32

4.14 TRANSMISSION ROTOR SUPPORT STRUT ASSEMBLIES (ET) ......... ................. 4-34

4.15 NACELLE CARRY-THROUGH POST ASSEMBLY (ET) .................. ........................ 4-35

4.16 WING ATTACHMENT FITTINGS ON WING AND FUSELAGE (ET) ........................ 4-38

4.17 WING RACK ATTACHMENT POINTS/MOUNTS (ET) ............................................. 4-41

4.18 TADS/PNVS SUPPORT FITTING (ET) .................................................................... 4-44

4.19 VERTICAL STABILIZER LUGS (ET) ........................................................................ 4-46

4.20 VERTICAL STABILIZER BARREL NUTS (MT) .......................... .............................. 4-48

4.21 HORIZONTAL STABILATOR ACTUATOR FITTING (ET) ................. ....................... 4-49

4.22 ENGINE ACCESS AND VENTILATION DOOR ASSEMBLY RIG

CONNECTING LINK (PT) ................................................ ........................................ 4-51

4.23 AFT INBOARD ENGINE MOUNT SUPPORT (ET) ................................................... 4-52

4.24 ENGINE NACELLE STRUT ATTACHMENT AREA (ET) .................. ........................ 4-55

4.25 MAIN LANDING GEAR TRAILING ARMS (MT) ......................... .............................. 4-56

4.26 MAIN LANDING GEAR WHEELS (ET) ................................. ................................... 4-58

4.27 MAIN LANDING GEAR SHOCK STRUT HOUSING, PISTON, AND ROD

ENDS (MT) .............................................................................................................. 4-62

4.28 MAIN LANDING GEAR LOWER STRUCTURAL SUPPORT (MT) ......... .................. 4-64

4.29 MAIN LANDING GEAR JACK PAD ADAPTER (MT) ..................... ........................... 4-65

4.30 MAIN LANDING GEAR TRAILING ARM CROSS TUBE (MT) ............. ..................... 4-68

4.31 MAIN LANDING GEAR SHOCK STRUT MOUNT SHAFT (MT) ........... .................... 4-70

4.32 TAIL LANDING GEAR FORK (ET) ........................................................................... 4-72

4.33 TAIL WHEEL (ET) ................................................... ................................................ 4-74

4.34 TAIL LANDING GEAR SHOCK STRUT (MT) ........................................................... 4-76

4.35 TAIL LANDING GEAR TRAILING ARMS (ET) .......................... ............................... 4-78

4.36 TAIL LANDING GEAR ACTUATING CYLINDER ASSEMBLY (ET) .......................... 4-79

4.37 BRAKE SYSTEM COMPONENTS (PT) ................................ ................................... 4-82

4.38 GENERAL HELICOPTER ATTACHING HARDWARE (MT) ............... ...................... 4-84

V ENGINE SYSTEM ............................................................. ......................................................... 5-1

5.1 CONTENTS ........................................................ ..................................................... 5-1

5.2 AFT INBOARD AND AFT LOWER ENGINE MOUNTS (ET) .............. ...................... 5-3

5.3 FORWARD INBOARD ENGINE MOUNT (MT) ........................ ................................ 5-4

5.4 FORWARD LOWER ENGINE MOUNT (MT) ............................ ............................... 5-6

5.5 ENGINE TUBING, COUPLINGS, AIR DUCTS, FITTINGS, SUPPORTS,

BRACKETS, AND CLIPS (PT) .................................. ............................................... 5-8

v
TM 1-1520-264-23

TABLE OF CONTENTS - Continued

Section/Paragraph Page

5.6 AIR INLET ASSEMBLY (ET) .................................................................................... 5-10

5.7 ENGINE AIR INLET "V" BAND CLAMP (PT) ............................................................ 5-13

5.8 STARTER FLANGE (ET) ............................................ ............................................. 5-14

5.9 ENGINE SHROUD (PT) ........................................................................................... 5-16

5.10 ENGINE LOAD DEMAND SPINDLE BELLCRANK SUPPORT (ET) ......................... 5-18

5.11 ENGINE COMPONENTS (PT) ................................................................................. 5-20

VI FLIGHT CONTROL SYSTEM .................................................. ................................................... 6-1

6.1 CONTENTS ........................................................ ..................................................... 6-1

6.2 FLIGHT CONTROL BELLCRANKS (ET) .................. .............................................. 6-5

6.3 MAIN ROTOR SWASHPLATE SHOULDER PIN MATING BORES (ET) .................. 6-6

6.4 MAIN ROTOR LINK BARRELS (MT) ................................ ....................................... 6-9

6.5 MAIN ROTOR SCISSORS UPPER ARM (ET) .......................... ............................... 6-11

6.6 MAIN ROTOR SCISSORS LOWER ARM (ET) .......................... .............................. 6-13

6.7 PILOT/CPG COLLECTIVE STICK TUBE (ET) ........................... .............................. 6-15

6.8 PILOT/CPG COLLECTIVE STICK ROTOR HOUSING (ET) ..................................... 6-17

6.9 PILOT COLLECTIVE STICK CYLINDER (ET) .......................................................... 6-19

6.10 FLIGHT CONTROL RODS, CONNECTING LINKS, ROD ENDS,

CLEVISES, LEVERS, AND ATTACHING PARTS (ET) ................. ........................... 6-21

6.11 PILOT COLLECTIVE STICK SUPPORT ASSEMBLY (ET) ................ ...................... 6-22

6.12 CPG COLLECTIVE STICK SUPPORT ASSEMBLY (ET) ................. ........................ 6-25

6.13 PILOT CYCLIC STICK (ET) .......................................... ........................................... 6-27

6.14 LATERAL FEEL SPRING CARTRIDGE (ET) ............................ ............................... 6-29

6.15 PILOT CYCLIC STICK HOUSING AND SUPPORT ASSEMBLY (ET) ...................... 6-31

6.16 CPG CYCLIC STICK FORWARD AND AFT LINKS (ET) ................. ........................ 6-34

6.17 CPG CYCLIC STICK REMOTE CONTROL LEVER (ET) ................. ........................ 6-35

6.18 CPG CYCLIC STICK FITTING ASSEMBLY (ET) ........................ ............................. 6-38

6.19 FERROUS FLIGHT CONTROL SYSTEM PUSH-PULL RODS (MT) ....... ................. 6-41

6.20 NONFERROUS FLIGHT CONTROL SYSTEM PUSH-PULL RODS (ET) ... .............. 6-43

6.21 CPG TO PILOT LONGITUDINAL F.S. 82.80 CONTROL BRACKET (ET) ... ............ 6-46

6.22 CPG TO PILOT COLLECTIVE F.S. 118.50 BELLCRANK (ET) ............ ................... 6-48

6.23 CPG DIRECTIONAL SHEAR PIN ACTIVATED DECOUPLER (SPAD)

ARMS (ET) ....................................................... ....................................................... 6-50

6.24 DIRECTIONAL F.S. 121.40 BELLCRANK (ET) .......................... ............................. 6-52

6.25 DIRECTIONAL F.S. 121.40 BELLCRANK BRACKET (ET) ...................................... 6-54

6.26 PILOT DIRECTIONAL SHEAR PIN ACTIVATED DECOUPLER (SPAD)

TRANSDUCER ARM (ET) ....................................................................................... 6-56

6.27 PILOT DIRECTIONAL SHEAR PIN ACTIVATED DECOUPLER (SPAD)

REMOTE CONTROL LEVER (ET) ........................................................................... 6-58

vi
TM 1-1520-264-23

TABLE OF CONTENTS - Continued

Section/Paragraph Page

6.28 PILOT DIRECTIONAL SHEAR PIN ACTIVATED DECOUPLER (SPAD)

BELLCRANKS (ET) ............................................... .................................................. 6-60

6.29 DIRECTIONAL F.S. 156.07 BELLCRANK (ET) .................... ................................... 6-62

6.30 DIRECTIONAL F.S. 159.98 BELLCRANK AND BRACKET (ET) ........... .................. 6-64

6.31 DIRECTIONAL F.S. 164.33 BELLCRANK BRACKET AND ATTACHING

AREA ON DECK (ET) ............................................. ................................................. 6-66

6.32 PILOT LONGITUDINAL SHEAR PIN ACTIVATED DECOUPLER (SPAD)

OUTER AND INNER LEVER (ET) ............................................................................ 6-68

6.33 PILOT/CPG DIRECTIONAL CONTROL PEDAL RELEASE HANDLE (ET) ............... 6-69

6.34 PILOT/CPG DIRECTIONAL CONTROL PEDAL RELEASE SHAFT (MT) ................. 6-73

6.35 PILOT/CPG DIRECTIONAL CONTROL PEDAL RELEASE NUTS (MT) .................. 6-75

6.36 DIRECTIONAL F.S. 199.25 TAIL ROTOR FITTING (ET) ................. ....................... 6-77

6.37 DIRECTIONAL F.S. 275 ROTOR CONTROL BRACKET (ET) ............. ................... 6-79

6.38 DIRECTIONAL F.S. 348 BELLCRANK (ET) ............................. ............................... 6-81

6.39 DIRECTIONAL F.S. 348 TAIL ROTOR BRACKET (ET) ................... ....................... 6-83

6.40 TAIL ROTOR SWASHPLATE CONTROL BELLCRANK (MT) .................................. 6-85

6.41 TAIL ROTOR DRIVE LINKS (ET) ............................................................................. 6-86

6.42 EXTERIOR SURFACES OF ALL FERROUS HYDRAULIC COMPONENTS

(SERVOCYLINDERS, ACTUATORS, RESERVOIRS, ETC.) (MT) ........................... 6-88

APPENDIX A MAINTENANCE ALLOCATION CHART ................................................................... A-1

APPENDIX B EQUIPMENT LISTING . . .............................................................................. B-1

APPENDIX C ILLUSTRATED FIELD MANUFACTURE ITEMS LIST .............................................. C-1

ALPHABETICAL INDEX .............................................................................................................................Index 1

vii
TM 1-1520-264-23

LIST OF ILLUSTRATIONS

Figure Title Page

1-1 Nondestructive Inspection Symbols .................................................................................... 1-7

1-2 General Configuration of AH-64A Helicopter ............................... ....................................... 1-9

1-3 Fuselage Stations, Buttlines, Centerline, and Waterlines .................................................... 1-10

1-4 Access Provisions ................................................. ............................................................. 1-14

1-5 Bond Testing Reference Block Displays ................................. ............................................ 1-25

1-6 Portable Magnetic Particle Inspection Equipment ............................................................... 1-33

1-7 Signatures of EDM Notches in Test Block .................................... ...................................... 1-39

1-8 Typical Metal Sorting Display .......................................... ................................................... 1-40

2-1 Rotor System .......................................................... .......................................................... 2-3

2-2 Main Rotor Droop Stop Follower (Plunger) .............................. ........................................... 2-6

2-3 Droop Stop Ring ................................................................................................................. 2-8

2-4 Main Rotor Blade (Voids) ............................................. ...................................................... 2-10

2-5 Main Rotor Blade .................................................... ........................................................... 2-13

2-6 Main Rotor Blade ........................................................ ....................................................... 2-15

2-7 Main Rotor Blade Weight Support Fittings .......................................................................... 2-18

2-8 Main Rotor Mast ................................................................................................................. 2-21

2-9 Main Rotor Mast Retaining Ring ......................................................................................... 2-22

2-10 Main Rotor Hub Retention Nut ............................................................................................ 2-24

2-11 Main Rotor Head (Hub) ...................................................................................................... 2-26

2-12 Main Rotor Lead Lag Link (Damper Link) ............................... ............................................ 2-29

2-13 Main Rotor Damper ............................................................................................................ 2-32

2-14 Main Rotor Damper Trunnion .......................................... ................................................... 2-34

2-15 Main Rotor Damper Rod End ........................................... .................................................. 2-36

2-16 Main Rotor Pitch Housing ................................................................................................... 2-39

2-17 Main Rotor Feathering Bearing Housing ............................................................................. 2-42

2-18 Main Rotor Striker Plate and Shims .................................................................................... 2-44

2-19 Main Rotor Hub Bearing ..................................................................................................... 2-47

2-20 Main Rotor Lower Shoe .................................................................................................... 2-49

2-21 Main Rotor Head Hub Load Plate ....................................................................................... 2-50

2-22 Main Rotor Hub Brackets ............................................. ...................................................... 2-52

2-23 Main Rotor Hub Lower Plate ............................................................................................... 2-53

2-24 Tail Rotor Fork Assembly (Head and Teeter Stop) ........................ ..................................... 2-56

2-25 Tail Rotor Blade ..................................................... ............................................................ 2-57

2-26 Tail Rotor Blade (Voids) ................................................. .................................................... 2-60

2-27 Tail Rotor Blades (Fluid) .............................................. ...................................................... 2-63

2-28 Tail Rotor Hub .................................................................................................................... 2-67

2-29 Tail Rotor Clamps and Locking Plates ................................................................................ 2-70

3-1 Drive System ................................................................. .................................................... 3-2

viii
TM 1-1520-264-23

LIST OF ILLUSTRATIONS - Continued

Figure Title Page

3-2 Drive Shafts ..................................................... .................................................................. 3-5

3-3 Drivetrain Couplings ........................................................................................................... 3-9

3-4 Drivetrain Flanges .............................................................................................................. 3-10

3-5 Damper and Anti-Flail Supports ........................................ ................................................. 3-13

3-6 Forward Hanger Bearing Flange ......................................................................................... 3-14

3-7 Forward Hanger Bearing Support ........................................ ............................................... 3-16

3-8 Aft Hanger Bearing Flange ................................................................................................. 3-19

3-9 Aft Hanger Bearing Support ........................................... .................................................... 3-21

3-10 Intermediate Gearbox Centrifugal Fan .................................. ............................................. 3-24

3-11 Engine Nose Gearbox ................................................ ........................................................ 3-27

3-12 Engine Nose Gearbox Input Quill Shaft .............................................................................. 3-28

3-13 Main Transmission ................................................... .......................................................... 3-31

3-14 Main Transmission Compressor Drive Adapter ................................................................... 3-34

3-15 Main Transmission APU Drive Flange ................................................................................ 3-35

3-16 Main Transmission Tail Rotor Drive Flange ........................................................................ 3-37

3-17 Main Rotor Gearshaft Drive Gear Teeth ............................................................................. 3-39

3-18 Main Rotor Mast Support Base ........................................................................................... 3-41

3-19 Intermediate Gearbox ................................................ ........................................................ 3-44

3-20 Intermediate Gearbox Retainers ......................................................................................... 3-47

3-21 Intermediate Gearbox Flange and Shouldered Shaft .......................................................... 3-49

3-22 Tail Rotor Gearbox ............................................................................................................. 3-52

3-23 Tail Rotor Gearbox Shouldered Shaft ................................................................................. 3-54

3-24 Tail Rotor Gearbox Retainers ............................................................................................. 3-57

3-25 Tail Rotor Gearbox Forward and Aft Strut ............................... ........................................... 3-58

3-26 Tail Rotor Gearbox Forward and Aft Strut Fittings ........................ ...................................... 3-61

4-1 Airframe and Landing Gear System .................................... ............................................... 4-3

4-2 Fuselage and Empennage Access Doors, Covers, Panels, Skins, and

Fairings - Metal .................................................... .............................................................. 4-7

4-3 Honeycomb Core Fuselage Panels, Vertical Fin, etc ................. ....................................... 4-9

4-4 Fluid in Honeycomb Core Fuselage Panels, Vertical Fin, etc .............................................. 4-12

4-5 Fittings, Castings, and Forgings ....................................... .................................................. 4-15

4-6 Transmission Deck ............................................................................................................. 4-17

4-7 Empennage Frame Assemblies F.S. 530 and F.S. 547 and Attached

Stringers .......................................................... .................................................................. 4-20

4-8 Fuselage Support Holes ................................................ ..................................................... 4-23

4-9 Gun and Ammo Support Mount Pads ................................... .............................................. 4-25

4-10 Main Landing Gear Shock Strut Support ................................ ............................................ 4-27

4-11 Main Landing Gear Cross Tube Mounting Points ................................................................ 4-30

ix
TM 1-1520-264-23

LIST OF ILLUSTRATIONS - Continued

Figure Title Page

4-12 Rotor Support Mixer Assembly and Mounting Surfaces ................... ................................... 4-31

4-13 Rotor Mixer Support Assembly Bolt ................................................................................... 4-33

4-14 Transmission Rotor Support Strut Assemblies .................................................................... 4-36

4-15 Nacelle Carry-Through Post Assembly .................................. ............................................. 4-39

4-16 Wing Attachment Fittings on Wing and Fuselage ......................... ...................................... 4-41

4-17 Wing Rack Attachment Points/Mounts ........................... .................................................... 4-43

4-18 TADS/PNVS Support Fitting ............................................................................................... 4-45

4-19 Vertical Stabilizer Lugs ....................................................................................................... 4-47

4-20 Vertical Stabilizer Barrel Nuts ............................................................................................. 4-49

4-21 Horizontal Stabilator Actuator Fitting .................................... .............................................. 4-51

4-22 Engine Access and Ventilation Door Assembly Rig Connecting Link ........ .......................... 4-53

4-23 Aft Inboard Engine Mount Support ..................................... ................................................ 4-54

4-24 Engine Nacelle Strut Attachment Area .................................. ............................................. 4-57

4-25 Main Landing Gear Trailing Arms ....................................................................................... 4-59

4-26 Main Landing Gear Wheels ................................................................................................ 4-61

4-27 Main Landing Gear Shock Strut Housing, Piston, and Rod Ends ........... ............................. 4-63

4-28 Main Landing Gear Lower Structural Support ............................. ........................................ 4-66

4-29 Main Landing Gear Jack Pad Adapter ................................... ............................................. 4-67

4-30 Main Landing Gear Trailing Arm Cross Tube ...................................................................... 4-69

4-31 Main Landing Gear Shock Strut Mount Shaft ...................................................................... 4-71

4-32 Tail Landing Gear Fork ............................................... ....................................................... 4-73

4-33 Tail Wheel .......................................................... ............................................................... 4-75

4-34 Tail Landing Gear Shock Strut ......................................... .................................................. 4-77

4-35 Tail Landing Gear Trailing Arms ......................................................................................... 4-80

4-36 Tail Landing Gear Actuating Cylinder .................................... ............................................. 4-82

4-37 Brake System Components ................................................................................................ 4-83

4-38 General Helicopter Attaching Hardware .............................................................................. 4-85

5-1 Engine System ................................................................................................................... 5-2

5-2 Aft Inboard and Aft Lower Engine Mounts ............................... ........................................... 5-5

5-3 Forward Inboard Engine Mount ........................................ .................................................. 5-7

5-4 Forward Lower Engine Mount ............................................................................................. 5-9

5-5 Engine Tubing, Couplings, Air Ducts, Fittings, Supports, Brackets, and

Clips ................................................................................................................................... 5-11

5-6 Air Inlet Assembly .................................................... .......................................................... 5-13

5-7 Engine Air Inlet "V" Band Clamp ....................................... ................................................. 5-14

5-8 Starter Flange ......................................................... ........................................................... 5-16

5-9 Engine Shroud ...................................................... ............................................................. 5-17

5-10 Engine Load Demand Spindle Bellcrank Support ......................... ...................................... 5-19

5-11 Engine Components .......................................................................................................... 5-21

x
TM 1-1520-264-23

LIST OF ILLUSTRATIONS - Continued

Figure Title Page

6-1 Flight Control System ......................................................................................................... 6-3

6-2 Flight Control Bellcranks .............................................. ...................................................... 6-7

6-3 Main Rotor Swashplate Shoulder Pin Mating Bores ............................................................ 6-8

6-4 Main Rotor Link Barrels ...................................................................................................... 6-10

6-5 Main Rotor Scissors Upper Arm ....................................... .................................................. 6-12

6-6 Main Rotor Scissors Lower Arm ........................................ ................................................. 6-14

6-7 Pilot/CPG Collective Stick Tube ......................................................................................... 6-16

6-8 Pilot/CPG Collective Stick Rotor Housing ........................................................................... 6-18

6-9 Pilot Collective Stick Cylinder .......................................... .................................................. 6-20

6-10 Flight Control Rods, Connecting Links, Rod Ends, Clevises, Levers,

and Attaching Parts ............................................................................................................ 6-23

6-11 Pilot Collective Stick Support Assembly .................................. ........................................... 6-25

6-12 CPG Collective Stick Support Assembly ................................ ............................................ 6-27

6-13 Pilot Cyclic Stick ...................................................... .......................................................... 6-29

6-14 Lateral Feel Spring Cartridge .......................................... ................................................... 6-31

6-15 Pilot Cyclic Stick Housing and Support Assembly .............................................................. 6-33

6-16 CPG Cyclic Stick Forward and Aft Links ............................................................................. 6-36

6-17 CPG Cyclic Stick Remote Control Lever ................................ ............................................ 6-38

6-18 CPG Cyclic Stick Fitting Assembly .................................................................................... 6-40

6-19 Ferrous Flight Control System Push-Pull Rods ................................................................... 6-42

6-20 Nonferrous Flight Control System Push-Pull Rods .............................................................. 6-45

6-21 CPG to Pilot Longitudinal F.S. 82.80 Control Bracket ........................................................ 6-47

6-22 CPG to Pilot Collective F.S. 118.50 Bellcrank ................................................................... 6-49

6-23 CPG Directional Shear Pin Activated Decoupler (SPAD) Arms ............. ............................. 6-51

6-24 Directional F.S. 121.40 Bellcrank ....................................... ............................................... 6-53

6-25 Directional F.S. 121.40 Bellcrank Bracket ............................... .......................................... 6-55

6-26 Pilot Directional Shear Pin Activated Decoupler (SPAD) Transducer Arm .... ..................... 6-57

6-27 Pilot Directional Shear Pin Activated Decoupler (SPAD) Remote Control

Lever........................................ .......................................................................................... 6-59

6-28 Pilot Directional Shear Pin Activated Decoupler (SPAD) Bellcranks ......... .......................... 6-61

6-29 Directional F.S. 156.07 Bellcrank ......................................... ............................................. 6-63

6-30 Directional F.S. 159.98 Bellcrank and Bracket ................................................................... 6-65

6-31 Directional F.S. 164.33 Bellcrank Bracket and Attaching Area on Deck ............................. 6-67

6-32 Pilot Longitudinal Shear Pin Activated Decoupler (SPAD) Outer and

Inner Lever ......................................................................................................................... 6-70

6-33 Pilot/CPG Directional Control Pedal Release Handle ..................... .................................... 6-72

6-34 Pilot/CPG Directional Control Pedal Release Shaft ........................ .................................... 6-74

6-35 Pilot/CPG Directional Control Pedal Release Nuts ......................... .................................... 6-76

xi
TM 1-1520-264-23

LIST OF ILLUSTRATIONS - Continued

Figure Title Page

6-36 Directional F.S. 199.25 Tail Rotor Fitting ........................................................................... 6-78

6-37 Directional F.S. 275 Rotor Control Bracket ........................................................................ 6-80

6-38 Directional F.S. 348 Bellcrank ......................................... .................................................. 6-82

6-39 Directional F.S. 348 Tail Rotor Bracket .................................. ........................................... 6-84

6-40 Tail Rotor Swashplate Control Bellcrank ............................................................................. 6-86

6-41 Tail Rotor Drive Links ......................................................................................................... 6-88

6-42 Exterior Surfaces of All Ferrous Hydraulic Components (Servocylinders,

Actuators, Reservoirs, etc.) ......................................... ....................................................... 6-90

xii
TM 1-1520-264-23

LIST OF TABLES

Number Title Page

1-1 Supporting Technical Documentation ....................................................................... 1-3

1-2 Access Provisions ................................................... ................................................. 1-17

1-3 Penetrant Procedure (Type I, Method A) ................................. ................................. 1-28

1-4 Penetrant Procedure (Type I, Method B) ................................ .................................. 1-29

1-5 Penetrant Procedure-Portable or Field Application (Type I, Method C) ................... 1-30

1-6 Penetrant Procedure (Type I, Method D) ................................. ................................. 1-31

1-7 Equipment Used for NDI .................................................. ........................................ 1-42

1-8 Materials Used for NDI ............................................................................................. 1-43

2-1 Rotor System Inspection Index ................................................................................. 2-1

3-1 Drive System Inspection Index ................................................................................. 3-1

4-1 Airframe and Landing Gear System Inspection Index ............................................... 4-1

5-1 Engine System Inspection Index ....................................... ....................................... 5-1

6-1 Flight Control System Inspection Index ................................. ................................... 6-1

xiii/(xiv blank)
TM 1-1520-264-23

SECTION I

INTRODUCTION

1. INTRODUCTION.

a. This manual contains instructions for accomplishing Nondestructive Inspection (NDI) of the AH-64A helicopter at

the AVUM and AVIM levels. The procedures described in this manual are intended to provide instructions for the NDI of

locations where service defects would prevent items from performing their designated functions, and of components for

serviceability. These procedures were developed through review of AH-64A Aircraft Technical Manual inspection

requirements. The goal is to upgrade these requirements wherever possible using NDI methodology to improve

inspection quality, decrease inspection time, and increase systems operational readiness. Other factors involved were

maintenance engineering analysis, experience, and comparison with similar installations. Procedures shall be reviewed

and changes and additions made during the service life of the equipment by continually evaluating the following:

performance of the equipment, results of scheduled inspections, and thorough study of failure data. Local conditions,

such as special utilization of climatic environment, may dictate more detailed inspections. Commanders and their

maintenance officers are expected to exercise their prerogative to increase the frequency and scope of any inspection as

required.

b. This manual may pertain to part, or all types and series, of a model, and may, therefore, contain requirements

applicable to specific equipment that is not installed on an individual model. When this situation is encountered, those

requirements that are not applicable should be disregarded.

c. This manual does not contain inspection level or frequency, acceptance and rejection limitations, nor instructions

for correcting defective conditions. Inspection levels and frequency are provided in the inspection requirements

manuals. Detailed acceptance and rejection criteria and instructions for correcting defective conditions are provided in

applicable maintenance manuals and are, therefore, not contained in this manual. Decisions regarding the serviceability

of components properly belong with maintenance technicians trained, skilled, and experienced in their particular

specialty, such as airframe, hydraulic, or propulsion. Also, it would duplicate existing information and make the task of

incorporating the numerous changes to inspection frequency and repair instructions impractical.

d. The inspection requirements are stated in such a manner as to address the following: (1) What part or area is to

be inspected? (2) What conditions are to be sought? (3) What NDI method is to be used? (4) How is the method to be

performed? In scope, the inspection procedures are designed to direct attention of maintenance personnel to

components and areas where service defects can occur. The procedures also provide detailed instructions on the

application of NDI in an effort to ensure the serviceability of these areas.

e. Nondestructive inspection methods require application by trained, experienced, and proficient technicians. This

manual provides detailed procedures for the application of nondestructive methods to inspect specific areas or locations.

However, it must be emphasized that the reliability of the inspection depends upon the proper evaluation of the results

obtained from the inspection equipment.

1-1
TM 1-1520-264-23

f. While using this manual, such adjectives as left and right, upper and lower, front and rear, forward and aft, and

clockwise and counterclockwise refer to the helicopter as viewed from the rear (aft), looking forward.

g. Changes and supplements to this manual will be published when necessary to add, delete, or change the scope

of requirements. Such changes will be based on factual data accumulated as a result of maintenance experience with

the equipment. Suggested new or revised field developed inspection procedures or changes to this manual are

encouraged and should be made by submitting a DA Form 2028. Mail to: U.S. Army Aviation and Troop Command,

ATTN: AMSAT-I-MP, 4300 Goodfellow Boulevard, St. Louis, MO 63120-1798.

h. These NDI procedures are directive in nature, and deviation without prior approval is limited to compensation for

differences in equipment output. Equipment settings, when given, are reference points only, due to the widely varying

outputs from different inspection equipment. The condition that must be satisfied for accurate inspection is that the

inspection equipment be adjusted to obtain the specified response from the set-up or defect standard, or the specified

density reading on radiographic film. Trained NDI technicians are qualified to make these adjustments.

1.1 GENERAL INFORMATION.

CAUTION

Misinterpretation of indications can result in rejectable parts being accepted and acceptable parts being

rejected. Only NDI personnel trained and qualified in accordance with applicable military standards and

technical manuals shall perform and interpret nondestructive inspections.

a. This manual provides necessary information to enable qualified personnel to perform NDI on AH-64A helicopter.

The selection of components in this manual is based on a review of applicable technical manuals listed in Table 1-1. All

existing NDI callouts were updated. New NDI procedures were developed for those parts that required check, inspect, or

any other NDI related actions. Section I of this manual contains a list of special terms, abbreviations, acronyms,

information on how to use the manual, use of NDI symbols, and a list of publications. Section I also contains general

information on the AH-64A helicopter, including descriptive data, access panels, major assemblies, stops, handholds,

walkways, various NDI method descriptions, and rules of safety to be observed during nondestructive inspections.

b. Additional information on inspection methods can be found in the Technical Manual, Nondestructive Inspection

Methods, TM 55-1500-335-23. Detailed inspection instructions for each main aircraft group are given in Sections II

through VI of this manual.

1-2
TM 1-1520-264-23

Table 1-1. Supporting Technical Documentation

Document Description

AR40-14/DLAR Medical Services, Control and Recording Procedures for

1000.28 Exposure to Ionizing Radiation and Radioactive Materials

ASTM-E1444 Standard Practice for Magnetic Particle Inspection

DA PAM 738-751 Functional Users Manual for the Army Maintenance Management

System - Aviation (TAMMS-A)

DOD 6050.5 (HMIS) Hazardous Materials Information System (HMIS)

FM 21-11 First Aid for Soldiers

MIL-STD-410 Nondestructive Testing, Personnel Qualification and Certification

MIL-STD-453 Inspection, Radiographic

MIL-STD-2154 Inspection, Ultrasonic, Wrought Metals, Process for

MIL-STD-6866 Inspection, Liquid Penetrant

TB MED 502 Occupational and Environmental Health Respiratory Protection

(DLAM 1000.2) Program

TB MED 251 Surgeon General's Hearing Conservation Criteria

TM 55-1500-335-23 Nondestructive Inspection Methods

TM 1-1500-344-23 Aircraft Weapons Systems Cleaning and Corrosion Control

TM 1-1520-238-23 Aviation Unit and Intermediate Maintenance Manual, Helicopter,

Attack, AH-64A Apache

Chapter 1 Aircraft General

Chapter 2 Airframe

Chapter 3 Landing Gear System

Chapter 4 Power Plant

Chapter 5 Rotors

Chapter 6 Drive System

1-3
TM 1-1520-264-23

Table 1-1. Supporting Technical Documentation - Continued

Document Description

Chapter 7 Hydraulic and Pneumatic Systems

Chapter 11 Flight Control System

TM 55-2840-248-23 Aviation Unit and Intermediate Maintenance Instructions, Engine

(series) Aircraft, Turboshaft Model T700-GE-701

1.1.1 Special Terms. Abbreviations. and Acronyms.

AC Alternating Current

APU Auxiliary Power Unit

AVIM Aviation Intermediate Maintenance

AVUM Aviation Unit Maintenance

BL Buttline

BT Bond Testing Method

C Celsius

CCW Counterclockwise

CL Centerline

CPG Co-Pilot/Gunner

CRT Cathode Ray Tube

CW Clockwise

DC Direct Current

EDM Electrically Discharged Machined Notches

ET Eddy Current Method

F Fahrenheit

FS Fuselage Station

FSH Full Screen Height

FWD Forward

HdB Horizontal Decibels (Gain)

H Pos Horizontal Position

HPF High Pass Filter

ID Inside Diameter

INBD Inboard

IR Infrared

KHz Kilohertz

LCD Liquid Crystal Display

1-4
TM 1-1520-264-23

LH Left-hand (left side of aircraft aft looking forward)

LPF Low Pass Filter

MAC Maintenance Allocation Chart

MAX Maximum

MHz Megahertz

MIN Minimum

MLG Main Landing Gear

M/R Main Rotor

MT Magnetic Particle Method

NDI Nondestructive Inspection

OUTBD Outboard

P/N Part Number

PSI Pounds per Square Inch

PSIG Pounds per Square Inch Gauged

PT Fluorescent Penetrant Method

RH Right-hand (right side of aircraft aft looking forward)

ROT Rotation

RT Radiographic Method

SPAD Shear Pin Activated Decoupler

STA Station

TLG Tail Landing Gear

TM Technical Manual

T/R Tail Rotor

UT Ultrasonic Method

VdB Vertical Decibels .(Gain)

V Pos Vertical Position

WL Waterline

1.1.2 How to Use This Manual. This manual is divided into six sections as follows:

I Introduction.

II Rotor System

III Drive System

IV Airframe and Landing Gear System

V Engine System

VI Flight Control System

1-5
TM 1-1520-264-23

Section I contains the introduction and general information pertaining to the AH-64A helicopter and Nondestructive

Inspections. Sections II through VI contain detailed inspection procedures for specific items located within each system.

In general, inspection items are grouped with respect to part location and function. To use the manual, it is necessary to

know the system and name of the inspection item.

When the system and part name are known:

a. Turn to the applicable section of the manual covering that system. Refer to the group inspection index table at

the beginning of the section. If the item is listed, the corresponding paragraph and figure number will be referenced in

the table.

b. Turn to referenced inspection paragraph and figure for detailed inspection information.

1.1.3 Inspection Item Code. When inspection items, due to their proximity, are grouped in one illustration, the figure

will be indexed using the inspection item code. This code consists of digits separated by dashes. In the text, the

inspection item is identified as follows:

a. The first digit refers to the section of the manual in which the item appears. Example:

Paragraph 2.5 is found in Section II.

b. The second digit refers to the item number or order that the part procedure occurs in the manual section. 

Example: Paragraph 2.5 refers to item or procedure 5.

1.1.4 Use of NDI Symbols. Nondestructive inspection symbols and their application to detail inspection figures are

shown in Figure 1-1. In the main figures of each section, NDI symbols representing the type of inspection associated

with a part will appear next to the item number on the figure.

1.1.5 Use of Reference Publications. This manual is applicable to the AH-64A helicopter. The technician shall be

responsible for using the applicable referenced TM for the helicopter being inspected.

1.1.6 Related Publications. Supporting TMs and reference materials are listed in Table 1-1.

1.1.7 Description. The AH-64A advanced attack helicopter is a twin engine helicopter designed specifically for the

attack helicopter role. The helicopter accommodates an aircrew of two in a tandem configuration. The helicopter

delivers various combinations of ordnance while providing maximum helicopter survivability and aircrew protection.

Maximum helicopter survivability is achieved by providing redundant systems/components ballistic resistance, high

impact survivability, reduced detectability, and wire strike protection. The wings provide mounting surfaces for four

external pylons, which can carry external fuel tanks, point target missiles, 2.75-inch folding fin aerial rocket launchers, or

a symmetrically loaded combination of any two weapon racks.

The helicopter is powered by two T700-GE-701 orT700-GE-701C engines which drive the main rotor through individual

engine nose-mounted gearboxes and a main transmission. The main transmission power takeoff shaft drives the tail

rotor through intermediate and tail rotor gearboxes.

1-6
TM 1-1520-264-23

METHOD OF INSPECTION

USED IN ILLUSTRATIONS TO IDENTIFY THE TYPE

OF INSPECTION METHODS BEING ILLUSTRATED

SUPPLEMENTAL SYMBOLS

NDI_AH-64_F1_1

Figure 1-1. Nondestructive Inspection Symbols

1-7
TM 1-1520-264-23

The auxiliary power unit drives the accessory drive section of the main transmission to provide full electrical, pneumatic,

and hydraulic power to-the helicopter when the main engines are not on line. The auxiliary power unit is also used to

provide pressurized air system air to start the main engines.

Flight controls are mechanically actuated, hydraulically powered, and electrically assisted in all flight control axes.

A curved canopy structure provides integral rollover protection. The canopy has a blast shield between the two crew

stations. Each crew station contains an adjustable armored seat. The seats incorporate armored wings which pivot to

facilitate entrance to, and exit from, the crew stations.

1.1.8 Configuration. The general configuration of the AH-64A helicopter is shown in Figure 1-2.

1.1.9 Airframe Stations. Fuselage stations, waterlines, buttlines, and centerlines provide an accurate method of

locating or installing parts and/or equipment in the airframe (Figure 1-3). All dimensions are in inches. Dimensions have

FS, WL, CL, or BL in front of the numbers.

a. Fuselage Stations. Fuselage stations (FS) are distances from a point in front of the helicopter nose. The first

station is zero (0.00).

b. Waterlines. Waterlines (WL) are distances from a point below the helicopter. They follow the centerline.

c. Centerline. Centerline (CL) is an imaginary line that passes through the center of the helicopter. The

centerline runs from the nose to the tail.

d. Buttlines. Buttlines (BL) are distances from the centerline. They start at the centerline and show the distance

to each side of the helicopter. Buttlines will be either to the left or right side.

These dimensions help you find any point on the helicopter. Each point shown on the following pages is a part of the

helicopter you can see.

1.2 TYPE OF CONSTRUCTION.

NOTE

The following paragraphs describe the type of construction and materials used in the manufacture of the

major AH-64A helicopter components.

1.2.1 Rotor System. The rotor system interfaces with the drive system and flight controls system.

The rotor system provides lift, thrust, directional flight, and anti-torque control for the helicopter. The rotor system

includes the 'main rotor assembly, a single, four-bladed, 48-foot diameter main rotor that provides vertical, longitudinal,

and lateral flight capabilities; the tail rotor assembly, a single, four-bladed, nine-foot diameter teetering tail rotor that

provides anti-torque and directional flight capabilities; and controls and indicators, various cockpit-mounted controls and

indicators used by the aircrew for operating the rotor system. The controls and indicators provide indications of system

operational performance.

The main rotor assembly is secured to the upper portion of the static mast and main drive shaft. The main rotor head

assembly is a fully articulated assembly that provides attachment points for the four main rotor blade assemblies. The

main rotor head assembly provides the means to drive the main rotor blade assemblies in a counterclockwise rotation

while providing feathering, flapping, and lead-lag movement of each blade.

1-8
TM 1-1520-264-23

NDI_AH-64_F1_2

Figure 1-2. General Configuration of AH-64A Helicopter

1-9
TM 1-1520-264-23

Figure 1-3. Fuselage Stations, Buttlines, Centerline, and Waterlines (Sheet 1 of 2)

1-10
TM 1-1520-264-23

Figure 1-3. Fuselage Stations, Buttlines, Centerline, and Waterlines (Sheet 2 of 2)

1-11
TM 1-1520-264-23

The main rotor head assembly is attached to the main drive shaft and static mast and provides mounting points for the

scissors and pitch change links. The main rotor head assembly transfers flight loads from the main rotor assembly to the

static mast, into the airframe. The main rotor head assembly requires no periodic lubrication.

The main rotor blade assemblies are rotating airfoils with swept tips that are constructed of stainless steel and fiberglass.

Each blade attaches to the main rotor head assembly by a lead-lag link and blade attachment pin.

The four lead-lag links are titanium mounts that provide a mounting point for each of the main rotor blade assemblies.

The four blade attachment pins are steel pins that attach to each of the lead-lag links to secure each main rotor blade

assembly to the main rotor head assembly.

The tail rotor assembly is installed on the tail rotor gearbox output shaft. The tail rotor assembly is a two-armed,

teetering assembly that provides attachment points for the four tail rotor blade assemblies. The tail rotor head assembly

provides a means to drive the tail rotor blade assemblies in a clockwise rotation providing feathering anti-torque control

for the helicopter. The tail rotor head assembly attaches to the tail gearbox output shaft and static support, providing

mounting points for the four pitch change links. The tail rotor head assembly transfers flight loads from the tail rotor

assembly to the static support, into the airframe.

The four tail rotor blade assemblies are rotating airfoils that are constructed of aluminum. Each tail rotor blade assembly

is attached to the tail rotor head assembly by a preload indicating washer, bolt, and nut combination.

1.2.2 Drive System. The main transmission assembly combines and reduces rpm from both engine nose gearboxes and

inputs usable engine power through the input clutch assemblies to the main rotor drive shaft and the main rotor head. It

is mounted on the main rotor static mast support directly below the main rotor static mast. Primary and accessory gear

trains are in the transmission housing and accessory drive housing assembly. They provide separate outputs for the

main rotor, tail rotor, transmission oil pumps, accessories, and rotor brake.

The main transmission assembly directs power from the auxiliary power unit to drive the accessories when the engines

are not operating. It also provides accessory drives for two AC generators, two hydraulic pumps, an accessory drive oil

pump, and a shaft-driven compressor. It provides mounting for accessory drive oil filters, two oil pressure switches, chip

detector/temperature switches, and an oil level sight indicator. During normal operation, the main transmission drives the

shaft-driven compressor, the accessory drive lubrication pump, two AC generators, two hydraulic pumps, tail rotor output

shaft, and the main rotor drive shaft.

The drive system consists of engine nose gearbox assemblies 1 and 2, the main transmission assembly, the intermediate

gearbox assembly, the tail rotor gearbox assembly, and the drive shaft assembly (7 drive shafts). The drive system

changes the angle of drive and converts the output rpm of the engines into usable power to drive the main rotor system,

tail rotor system, and the gear driven accessories.

1.2.3 Airframe and Landing Gear System. The airframe provides mounting points for the helicopter systems/subsystems

and components. The design features incorporated into the airframe increase both aircraft and aircrew survivability. The

airframe is a one-piece integral design that has the strength to withstand compression, tension, torsion, and shearing

force loads that exceed the required design limits throughout the entire flight envelope.

1-12
TM 1-1520-264-23

The fuselage is a semi-monocoque construction which greatly reduces the potential of catastrophic damage to the

fuselage. Fuselage strength and rigidity is obtained through the structural members and the skin. Some airframe

components are constructed with Kevlar. Kevlar is a synthetic resin-base fiber composite.

Airframe components have silver/aluminum tape, aluminum tape, conductive gaskets and retainers, and conductive

surfaces for gaskets installed to prevent electro-magnetic interference. The landing gear system provides support and

ground stability for helicopter fuselage during taxiing, takeoff, landing, towing, and parking. The system damps and

absorbs landing shocks before they can be transmitted to the airframe structure. The system provides for mounting of

helicopter wheel brakes. The brake system provides ground speed control and braking, and assistance in maneuvering

the helicopter during ground taxi operations.

1.2.4 Engine System. The engine system consists of two General Electric T700-GE-701 or T700-GE-701 C front drive

turboshaft engines. The T700-GE-701 provides 1,546 shaft horsepower and the T700-GE-701C provides 1,690 shaft

horsepower at 20,900 rpm engine torque (Np), to drive the main transmission.

1.2.5 Flight Control System. The flight controls system establishes vertical (up and down), longitudinal (forward and

backward), lateral (left and right), and directional (heading) flight of the helicopter through crew-initiated mechanical

inputs. Helicopter flight control is maintained by demand inputs to the main rotor, tail rotor, and stabilator in the pitch,

roll, and yaw axes.

Mechanical flight controls are provided for the pilot and copilot. Hydraulic pressure boosts crew-initiated control stick and

pedal movements by use of servocylinders operating at 3000 psi. The primary hydraulic system provides power for the

collective, longitudinal, lateral, and directional control servocylinders. The servocylinders are grounded to prevent

electro-magnetic interference. The utility hydraulic system provides redundant hydraulic power to the servocylinders and

utility hydraulic system components. Digital automatic stabilization equipment aids in stabilizing helicopter flight attitudes

and reducing pilot workload. Flight control can be maintained by use of a fly-by-wire backup control system if

mechanical control is lost. All mechanical control linkages are routed separately from the backup control system to

preclude the loss of both systems from a single projectile impact. Selectable and adjustable trim/feel units are provided

for the cyclic control sticks and directional pedals to maintain desired stick and pedal position. A horizontal stabilator

improves handling characteristics of the helicopter at various airspeeds.

1.2.6 Access Provisions. Access provisions consist of the access doors, covers, panels, and fairings. Inspection of the

helicopter and its components can be done through principal access provisions. Principal access and inspection

openings are shown in Figure 1-4 and listed in Table 1-2.

To prevent injury to personnel and damage to helicopter, stand only on designated surfaces. These

areas are reinforced to withstand frequent use and are treaded to prevent slipping. All other surfaces are

NO STEP areas.

1.2.7 Steps. Handholds. and Walkways. Steps, handholds, and walkways aid in doing maintenance, inspections, and

servicing on the helicopter.

1-13
TM 1-1520-264-23

Figure 1-4. Access Provisions (Sheet 1 of 3)

1-14
TM 1-1520-264-23

Figure 1-4. Access Provisions (Sheet 2 of 3)

1-15
TM 1-1520-264-23

Figure 1-4. Access Provisions (Sheet 3 of 3)

1-16
TM 1-1520-264-23

Table 1-2. Access Provisions

Item

Number Item Access To

Left Side

L40 Cover Electronic Equipment

L60 Fairing Forward Avionics Bay Nose

L90 Door IHADSS and PNVS Boxes and ICU

L115 Door Mooring Lug

L117 Door Rounds Counter

L120 Fairing Shock Strut Attach Fitting

L140 Fairing Ammunition Feed Mechanism (forward)

L160 Cover Pilot Collective Bellcrank

L165 Cover Rectifier

L175 Fairing Ammunition Feed Mechanism (aft)

L187 Door Hydraulic Return Accumulator Manifold

L190 Door Hydraulic Oil Level Sight Gage and Controls Access

L194 Fairing Ammunition Feed Mechanism

L200 Panel Main Rotor Transmission

L210 Door Main Transmission Oil Level Sight Gage

L225 Door Oil Tank Level Viewing Glass

L230 Fairing Hydraulic Heat Exchanger

L295 Door Aft Stowage Bay

L300 Fairing Environmental Control Unit Exhaust

L325 Door Walkway Access - Deck Area

L330 Door Fuselage Stowage Compartment

L510 Fairing Vertical Stabilizer

L530 Fairing Vertical Stabilizer, Leading Edge

L540 Fairing Tail Rotor Transmission

L545 Cover Tailboom

L546 Fairing Tail Rotor Transmission

L548 Fairing Stabilator Tip

L550 Fairing Vertical Stabilizer, Trailing Edge

P1 Fairing Pylon Nose

P2 Fairing Station Director

P3 Fairing Extended Range Kit and Multiplexer

LW10 Fairing Wing (Upper)

LW11 Fairing Wing (Lower)

LW12 Door Maintenance Intercom

Right Side

R40 Cover Electronic Equipment

R60 Fairing Forward Avionics Bay Nose

R90 Door Laser, PNVS, MUX, HF Remote

R115 Door Mooring Lug

R120 Fairing Shock Strut Attach Fitting

1-17
TM 1-1520-264-23

Table 1-2. Access Provisions - Continued

Item

Number Item Access To

Right Side - Continued

R155 Door Fire Extinguisher

R160 Door Refueling Controls

R170 Cap Gravity Refueling (forward)

R175 Fairing Ammunition Feed Mechanism (aft)

R180 Cover Pressure Refueling

R190 Door Transmission Inspection

R194 Fairing Ammunition Feed Mechanism

R200 Panel Main Rotor Transmission

R210 Door Transmission Area

R225 Door Engine

R230 Fairing Hydraulic Heat Exchanger

R265 Cap Gravity Refueling

R295 Door Aft Electronics Equipment

R325 Door Hydraulic Equipment

R330 Door Fuselage Stowage Compartment

R345 Door External Power

R365 Panel ADF Loop (anterior)

R410 Fairing Tail Rotor Drive Shaft

R475 Fairing Tail Rotor Drive Shaft

R510 Fairing Vertical Stabilizer

R545 Cover Tailboom

R548 Fairing Stabilator Tip

R578 Door Antenna Connection

P1 Fairing Pylon Nose

P2 Fairing Station Director (Strut must be removed at bottom)

P3 Fairing Extended Range Kit and Multiplexer

RW10 Fairing Wing (Upper)

RW11 Fairing Wing (Lower)

RW12 Door Maintenance Intercom

Top Side

L135 Door Main Landing Gear Shock Strut

LW7 Cover Pylon Connector

LW8 Cover Pylon Connector

LW9 Cover Hydraulic Lines and Electrical Wiring

LW13 Fairing Hydraulic and Pilot Lines and Electrical Wiring

R105 Fairing Ammunition Chute (Right Forward)

R135 Door Main Landing Gear Shock Strut

RW7 Cover Pylon Connector

1-18
TM 1-1520-264-23

Table 1-2. Access Provisions - Continued

Item

Number Item Access To

Top Side - Continued

RW8 Cover Pylon Connector

RW9 Cover Hydraulic Lines and Electrical Wiring

RW13 Fairing Hydraulic and Pilot Lines and Electrical Wiring

T50 Door Canopy Emergency Release

T185 Fairing Doghouse

T185A Cover Doghouse

T205 Cover I/R Jammer

T225 Fairing Main Rotor Shaft

T355* Fairing Tail Rotor Shaft

T205L Fairing Main Rotor Shaft

T250R Fairing Main Rotor Shaft

T545 Fairing Vertical Stabilizer

T545A Fairing Vertical Stabilizer

B40R Door Flight Controls

B41R Door Flight Controls

B60# Door Cyclic Stick Controls

B60R Door Utility Light and Ground Power Receptacle

B65L# Door Flight Controls

B65R# Door Flight Controls

B75R Door Cyclic Stick

B80L Cover FAB and Controls

B80R Cover FAB and Controls

B85L Cover Flight Controls

B85R Cover Flight Controls

B90 Fairing Gun Turret Bay

B92L Cover Flight Controls

B92R Cover Environmental Control System

B120 Fairing Gun Turret Bay

B170# Door Fuel Dump Valve

B200 Door Ammunition Bay

B250# Door Fuel Dump Valve

B330* Fairing Doppler Radar and Radar Altimeters

LN2* Door Water Wash

LN3 Door Engine

LN4 Door Engine

LN5 Door Engine

LN6* Fairing Engine Nose Gearbox

RN2 * Door Water Wash

RN3 Door Engine

RN4 Door Engine

1-19
TM 1-1520-264-23

Table 1-2. Access Provisions - Continued

Item

Number Item Access To

Top Side - Continued

R140 Fairing Ammunition Feed Mechanism (forward) (R115 and R155

must be open)

RN5 Door Oil Tank Level Viewing Glass

RN6* Fairing Engine Nose Gearbox

LS1 * Door Stabilator

RS1 * Door Stabilator

Top Side Engine Work Platform and Equipment Bay

LN1 Door Engine Work Platform

RN1 Door Engine Work Platform

T250L Door Deck Area

T290L Door Deck Area

T250R Door Deck Area

T290R Door Deck Area

T325 Fairing Deck Area

Pilot Left and Right Console Panels Removal/Installation

PL1 Aft Console Pilot Armored Crew Seat Removed

Panel

PL3 Center

Console

Panel

PL5 Map Case

Console

Panel

PL7 Forward Pilot Scuff Plate Assembly Removed

Console CPG Armored Crew Seat Removed

Panel

PR2 Forward Pilot Scuff Plate Assembly Removed

Console CPG Armored Crew Seat Removed

Panel

PR4 Center ECS Duct Removed

Console Helmet Holster Removed

Panel

PR6 Aft Console ECS Duct Removed

Panel

1-20
TM 1-1520-264-23

Table 1-2. Access Provisions - Continued

Item

Number Item Access To

CPG Left and Right Console Panels Removal/Installation

CL1 Aft Console CPG Armored Crew Seat Removed

Panel CPG Collective Cover Removed

CL3 Lower Aft ECS Crew Station Valve Removed

Console

Panel

CL5 Center

Console

Panel

CL7 Forward CPG Armored Crew Seat Removed

Console CPG Scuff Plate Assembly Removed

Panel CPG ICS Foot Switch Removed

CR2 Aft Console

Panel

CR4 Center Helmet Holster Removed

Console ECS Valve Removed

Panel

CR6 Forward CPG Armored Crew Seat Removed

Console CPG Scuff Plate Assembly Removed

Panel CPG ICS Foot Switch Removed

1.3 MARKING AND/OR RECORDING OF INSPECTION RESULTS.

NOTE

Only approved marking pencils listed in Table 1-8 are to be used for temporary marking of indications

found during an NDI inspection. The color of the markings shall contrast with the color of the part.

a. Wipe the area to be marked with low-lint cleaning cloth, MIL-C-85043.

b. Mark surface with appropriate color aircraft marking pencil, MIL-P-83953, using a light touch.

c. Remove markings as soon as there is no further need for them with a low-lint cloth, MIL-C-85043, dampened 

with tap water. It is allowable for a shadow of the marking to remain on surfaces after removal.

1-21
TM 1-1520-264-23

Cleaning solvents P-D-680, Type II and MIL-C-38736 are flammable. Avoid eye and skin contact or

breathing of vapors. Protective equipment consisting of goggles, gloves, and respiratory protection is

required.

Do not use cleaning solvent MIL-C-38736 on acrylic lacquer, as it may soften finish.

d. Dry-cleaning solvent, P-D-680, Type II shall be used for removal of markings on acrylic lacquer surfaces.

e. Record inspection results as required by the applicable technical manual listed in Table 1-1.

1.4 NONDESTRUCTIVE INSPECTION METHODS.

1.4.1 Purpose of Nondestructive Inspection (NDI). Methods used in NDI are those that may be applied to inspect a

structure or component to determine its ability to perform its intended function without damaging or causing any change

in the characteristics of the structure or component. During manufacture, aircraft components are given in-process and

final inspections. The most commonly used methods are magnetic particle and liquid penetrant because these two

methods are bulk processes that provide 100 percent inspection coverage and they are highly effective. It is unusual, but

possible, for NDI personnel to locate defects that are inherent (associated with the production of the material) or related

to the manufacturing operations. It follows that nearly all maintenance nondestructive inspection requirements are to

locate defects that have developed during service (i.e., corrosion and corrosion induced cracking; fatigue cracks; and

defects resulting from mechanical damage, improper maintenance, or inappropriate use). It is important that NDI

personnel shall be able to distinguish between inherent or in-service defects. A general knowledge of typical sites for inservice defect occurrence and specific knowledge of the mode and location of previous cracking problems for a particular

part are relevant. This knowledge will assure that the crack prone areas are identified for inspection and time will not be

wasted inspecting areas not subject to in-service cracking.

This manual summarizes the steps necessary to perform satisfactory inspections. It includes the preparation of the

helicopter, the inspection area for NDI, safety rules to be observed, highlights of each inspection method, and specific

safety precautions for each of these methods. For a detailed description of each method and its application, refer to the

Technical Manual, Nondestructive Inspection Methods, TM 55-1500-335-23. Specific instructions peculiar to each part

being inspected will be included in the discussion of that inspection item as it is covered in this manual.

1-22
TM 1-1520-264-23

1.4.2. Selecting the NDI Method. Factors governing the selection of an inspection method are: accessibility, portability

of equipment, type of suspected damage, material composition of part to be inspected, surface condition, and degree of

sensitivity required for the inspection. In many cases the method selected will depend primarily on accessibility and

practicality. For example, a threaded item that may qualify for eddy current inspection may instead require the

substitution of an ultrasonic inspection due to accessibility constraints. However, the ultrasonic inspection must be

capable of providing equivalent sensitivity. Also, the type of inspection desired may adversely affect adjacent parts.

Inspection methods in this manual were selected in order to provide maximum detection sensitivity while requiring a

minimum of removal or disassembly, and at the same time, protect adjacent areas from damage. Radiographic

inspection is used only to examine areas partly or totally hidden, or where the suspected damage is internal to the part.

Where one method of inspection (primary) reveals an indication of a crack, another method (backup) should be used to

verify if a crack is actually present. Quite often backup procedures are limited to disassembly and a good visual

inspection. Certain cases may arise when another NDI method could be used to prevent needless or complicated

disassembly. For example, a crack in a spar cap may not appear clearly on radiographic film due to cloudiness caused

by sealant or substructure clutter. A backup eddy current or ultrasonic method could be used for verification and if no

indications were observed, disassembly would not be necessary. Whenever a backup method is used, it shall be

specified in every case where the initial damage indication may not be positive proof that a reject condition exists.

1.4.3 Preparation of Helicopter for NDI. Prior to NDI, the helicopter shall be prepared for safe ground maintenance in

accordance with applicable technical manuals listed in Table 1-1.

1.4.4 Preparation of Part or Area for NDI.

Prolonged breathing of vapor from organic solvents, degreasers, or paint thinners is dangerous. Use

respirators in confined areas per Occupational and Environmental Health Respiratory Protection

Program (TB MED 502 (DLAM 1000.2)). Have adequate ventilation. Avoid prolonged skin contact.

Wear rubber gloves and goggles.

All NDI methods require proper cleanliness of the part or area being inspected. Refer to Table 1-1 for the applicable

cleaning and corrosion control manual. The cleaning technique to be used will be determined by the type of foreign

matter present, NDI method to be performed, and if the part is plated, painted, or has a protective coating. Scale and

corrosion shall be removed completely before inspection. If removal of protective coatings, such as paint, phosphate

coatings, black oxide, etc., is required, do not use removal methods that mechanically abrade the surface of the part to

be inspected since this may cause damage or mask over potential surface cracks on the part. Some inspection methods,

by their particular nature, will require that small openings and/or oil holes leading to obscure passages or cavities be

plugged, such as in the case of engine parts. A suitable nonabrasive material (i.e., vaseline, grease, paraffin) should be

used that is soluble in oil and can be readily removed. Effective masking shall be used to protect those components,

such as bearings and certain nonmetallics, that may be damaged by contact with the inspection solution or medium.

1-23
TM 1-1520-264-23

1.4.5 NDI General Safety Precautions.

Electrical equipment shall not be operated in areas where combustible gases or vapors may be present,

unless the equipment is explosion proof.

Prior to conducting an NDI inspection, survey the general area in advance. Eliminate possible hazards created by loose

structures, protruding workstands, and support equipment. Secure loose electric cords and remove toxic fluids or fumes.

If AC power is supplied to equipment, be sure that equipment is well grounded to prevent electrical hazards. Specific

safety instructions for each NDI method used in this manual are contained in the paragraph immediately following the

discussion of that method.

1.4.6 Bond Testing (BT) Method.

NOTE

Inspection of bonded structures shall be performed in accordance with the general applications and

techniques in TM 55-1500-335-23 (Nondestructive Inspection Methods manual) and the specific

requirements of this technical manual.

A number of different methods of NDI can be applied to the many configurations and types of bonded structures that are

in use. Variables such as skin material and thickness, adhesive type and thickness, underlying structure, and

accessibility are all factors in the development of specific inspection procedures. Because of the many inspection

methods and structural configurations, each application must be considered and reference standards representative of

the structure must be evaluated to verify proposed techniques.

1.4.6.1 Bond Testing Equipment. The bond testing equipment, Bondmaster, used in the procedures in this manual,

operates by generating a mechanical vibration into the material being tested. This equipment is designed to detect flaws

in adhesive bonded joints in composite structures. The instrument is capable of determining bad bonds, delaminations,

unbonds, and crushed honeycomb core defects. The Bondmaster has the following features:

a. Resonance. Detects unbonds and delaminations by changes in phase and amplitude at probe resonance. 

Couplant is required.

b. Pitch Catch Swept. Measures amplitude and phase changes using a swept frequency method to detect unbonds 

and deeper defects. Requires no couplant.

c. Pitch Catch Impulse. Measures amplitude and phase changes using a short burst of energy to detect unbonds. 

Requires no couplant.

d. Mechanical Impedance Analysis. Measures the effect of generated sound waves and the effect of loading as 

drive frequency is swept in the range of 2.5 KHz to 10 KHz. This method can be used on unbonds, crushed core,

and defects on the inside of composites. Requires no couplant. Refer to Figure 1-5, Bond Testing Reference 

Block Displays.

1-24
TM 1-1520-264-23

Figure 1-5. Bond Testing Reference Block Displays

1-25
TM 1-1520-264-23

Mechanical vibration energy generated by resonance test equipment can be measured, analyzed by the tester, then

displayed on a screen. There are several ways this energy can be applied to material and then be analyzed. Because

composite material properties differ substantially, no one test method will detect flaws in all types of material. For this

reason, current bond testing equipment incorporates at least one or more of the aforementioned features.

1.4.6.2 Safety Precautions During Bond Testing. Follow safety precautions and instructions contained in this manual

and the Nondestructive Inspection Methods manual listed in Table 1-1.

Electrical equipment shall not be operated in areas where combustible gases or vapors may be present, unless the

equipment is explosion proof.

a. If instrument is operated using AC power, use a grounded power cord.

b. Turn power OFF before connecting or disconnecting probe cable or power cable.

1.4.7 Fluorescent Penetrant (PT) Method.

NOTE

Fluorescent penetrant inspections shall be performed in accordance with the general applications and

techniques in TM 55-1500-335-23 (Nondestructive Inspection Methods manual) and the specific

requirements of this technical manual.

The basic purpose of fluorescent penetrant inspection is to increase the visible contrast between a discontinuity and its

background. This method is performed by applying a fluorescent penetrant solution to the inspection area which enters

the surface opening of the discontinuity. The area is then wiped or washed off and a developer is added to draw the

fluorescent material from the discontinuity. A flaw or crack in the part will then become visible under the influence of

ultraviolet light (black light). This method is effective for detecting surface flaws in forgings, castings, extrusions, formed

sections, webs, and skins of materials. The penetrant method of inspection requires that the surface-of the inspection

area be thoroughly cleaned. Paint on the part must be removed before inspection.

CAUTION

Penetrant-Emulsifier/Remover Combinations (lipophilic/hydrophilic) from one manufacturer may not be

mixed or used in conjunction with materials from a different manufacturer.

Four penetrant procedures are given in Tables 1-3, 1-4, 1-5, and 1-6. All four inspections shall be conducted using

fluorescent penetrant, MIL-1-25135, Type 1, Method A, B, C, or D, Sensitivity Level 3 or 4. Refer to the Nondestructive

Inspection Methods manual listed in Table 1-1 for more detailed instructions. Table 1-5 describes the procedure for

using Type I, Method C, Level 3 or 4 on a removed part or parts attached either to a component or to the helicopter. This

procedure supports the accomplishment of fluorescent penetrant inspection at the AVUM and AVIM levels regardless of

geographic location. Therefore, the procedure in Table 1-5 will be the one most frequently referred to

1-26
TM 1-1520-264-23

in this manual. Table 1-7 lists the equipment and Table 1-8 lists the fluorescent penetrant materials to be used.

1.4.7.1 Safety Precautions During Fluorescent Penetrant Inspection. Follow safety precautions and instructions

contained in this manual and the Nondestructive Inspection Methods manual listed in Table 1-1.

• Black lights generate considerable heat during use. Extreme care must be exercised to prevent contacting 

the housing with any part of the body.

• To prevent injury to eyes, do not look directly into black light.

• Prolonged direct exposure of hands to the filtered black light's main beam may be harmful. Suitable gloves 

should be worn when exposing hands to the main beam.

a. Follow manufacturer's instructions when using black lights and filter.

b. Do not wear sunglasses or glasses with light-sensitive lenses during fluorescent penetrant inspections. They can 

contribute to improper interpretation of defects.

Prolonged or repeated inhalation of vapors or powders may result in irritation of mucous membrane

areas of the nose.

c. Provide adequate ventilation when handling cleaner, emulsifier, penetrants, or developers.

Continual exposure to penetrant inspection material may cause skin irritation.

d. Observe the following when handling cleaners, emulsifiers, penetrants, or developers.

(1) Avoid contact with penetrant inspection materials by wearing neoprene gloves.

(2) Wash inside and outside of gloves.

(3) Wash exposed areas of body with soap and water.

(4) Check for traces of fluorescent penetrant materials on skin, clothing, and gloves using a black light source.

1-27
TM 1-1520-264-23

Table 1-3. Penetrant Procedure (Type I, Method A)

Task Description

a. Preparation of Part: Refer to Preparation of Part or Area for.ND!, paragraph 1.4.4.

b. Precleaning Procedure: Refer to TM 1-1500-344-23.

c. Penetrant Application: The penetrant may be applied by brushing, spraying, or dipping.

d. Penetrant Dwell: Allow a minimum of 30 minutes dwell time to a maximum of 240 minutes. Extended 

dwell time may require rewetting of parts.

e. Penetrant Removal/Rinse: Rinse the part by waterwash using a low-pressure spray (pressure not to exceed 20 

PSI) and a temperature of

16°C to 38°C (60°F to 100°F). DO NOT OVERRINSE.

f. Drying Operation: The parts should be dried in a circulating air dryer with a temperature range from 38°C 

to 60°C (100°F to 140°F). The time in the dryer should not exceed the time 

necessary to completely dry the surface of the parts.

g. Developer Application: The dry developer is sprayed or dusted lightly over the part to be inspected. Shake or 

blow off with low, oil-free air to remove excess developer.

h. Inspect: Perform inspection under black light.

i. Materials: Type I, Method A, Level 3 or 4 (water washable) Penetrant.

1-28
TM 1-1520-264-23

Table 1-4. Penetrant Procedure (Type I, Method B)

Task Description

a. Preparation of Part: Refer to Preparation of Part of Area for NDI, paragraph 1.4.4.

b. Precleaning Procedure: Refer to TM 1-1500-344-23.

c. Penetrant Application: The penetrant may be applied by brushing, spraying, or dipping

d. Penetrant Dwell: Allow a minimum of 30 minutes dwell time to a maximum of 240 minutes. Extended

dwell time may require rewetting of parts.

e. Emulsifier Application: The emulsifier may be applied by dipping or spraying. The preferred method of 

application is by dipping the part in the emulsifier. Do not permit emulsifier to

remain on the part over 3 minutes.

f. Rinse: Rinse the part by waterwash using a low-pressure spray (pressure not to exceed 40 

PSIG) and a temperature of 16°C to 38°C (60°F to 100°F).

g. Drying/Developer Operation: If a dry nonaqueous developer is to be used, first dry the part in a drying oven at a 

temperature not to exceed 60°C (1 40°F) until dry. Then apply the developer.

If an aqueous developer is to be used, then submerge the part in the developer

solution immediately after washing. Follow by drying the part in a drying oven as

mentioned above. In either case, parts shall be removed from the drying oven as

soon as they are dry.

h. Inspect: Perform inspection under black light.

i. Materials: Type I, Method B, Level 3 or 4 (post emulsifiable-lypophilic) Penetrant (Refer to 

Table 1-8.)

1-29
TM 1-1520-264-23

Table 1-5. Penetrant Procedure-Portable or Field Application

(Type I, Method C)

Task Description

a. Preparation of Part: Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

b. Precleaning Procedure: Refer to TM 1-1500-344-23.

c. Penetrant Application: Apply penetrant either by brushing or spraying. In a confined area, apply with brush to 

prevent overspray.

d. Penetrant Dwell: Allow a minimum of 30 minutes penetrant dwell time. In temperature below 16°C. 

(60°F), refer to Nondestructive Inspection Methods manual listed in Table 1-1 for 

dwell time compensations.

e. Penetrant Removal: Wipe dry with a dry, lint-free cloth. Wipe down with a solvent-moistening cloth. Check 

area to be inspected with black light to be sure all surface penetrant has been 

removed before applying developer. Do not spray cleaner directly onto part.

f. Developer Application: Spray a light film of developer over area to be inspected.

g. Inspect: Perform inspection under black light. Observe any obvious bleed-out as developer 

dries. Complete inspection after developer dwell time is complete.

h. Materials: Type I, Method C, Level 3 or 4, Solvent - Removable Fluorescent Dye Penetrant (Refer

to Table 1-8).

1-30
TM 1-1520-264-23

Table 1-6. Penetrant Procedure (Type I, Method D)

Task Description

a. Preparation of Part: Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

b. Precleaning Procedure: Refer to TM 1-1500-344-23.

c. Penetrant Application: The penetrant may be applied by brushing, spraying, or dipping.

d. Penetrant Dwell: Allow a minimum of 30 minutes dwell time to a maximum of 240 minutes. Extended 

dwell times may require rewetting of parts.

e. Penetrant Prerinse: Prerinse part with a water spray at a temperature of 16°C to 38°C (60°F to 100°F) 

and a spray pressure of 40 PSIG maximum. Do not overrinse.

f. Remover Application: Apply a solution as recommended by manufacturer of the specific hydrophilic 

remover in water to surface of the part. Dwell time shall be kept to an absolute 

minimum consistent with complete removal of excess penetrant.

g. Postrinse Operation: Postrinse part with a water spray at a temperature of 16°C to 38°C (60°F to 100°F) 

and a spray pressure of 40 PSIG maximum. Do not overrinse. Rinse 

effectiveness should be checked with a black light to ensure complete removal of 

penetrant remover.

h. Drying/Developer Operation: If a dry nonaqueous developer is to be used, first dry the part in a drying oven at a 

temperature not to exceed 60°C (140°F) until dry. Then apply the developer. If 

an aqueous developer is to be used, then submerge the part in the developer 

solution immediately after washing. Follow by drying the part in a drying oven as 

mentioned above. In either case, parts shall be removed from the drying oven as 

soon as they are dry.

i. Inspect: Perform inspection under black light.

j. Materials: Type 1, Method D, Level 3 or 4 (hydrophilic remover) Penetrant (Refer to Table 1-8).

1-31
TM 1-1520-264-23

Temperatures in excess of 49°C (120°F) may cause bursting of pressurized cans and injury to personnel.

e. Store all pressurized spray cans in a cool, dry area protected from direct sunlight. Avoid exposure of pressurized

spray cans to open flames.

Volatile fumes may occur, creating both a fire and health hazard.

f. Exercise extreme caution when handling penetrants that have been heated to a point where some lighter 

constituents are driven off.

1.4.7.2 Controlling Excess Fluorescent Penetrant. After fluorescent penetrant inspection, the part shall be thoroughly

cleaned to ensure all excess penetrant is removed from the part. This shall include removing the penetrant from cracks

as much as possible before disposition of the part. This can be easily accomplished by performing cleaning operations

under a black light.

1.4.8 Magnetic Particle (MT) Method.

NOTE

Magnetic particle inspection shall be performed in accordance with the general application and

techniques in TM 55-1500-335-23 (Nondestructive Inspection Methods manual) and the specific

requirements of this technical manual.

Magnetic particle is a method of detecting cracks or other flaws on the surface or near the surface of materials that are

ferromagnetic. This method will produce good indications of discontinuities, provided the part is free from grease, oil,

loose scale, or other surface contaminants. The inspection is accomplished on either assembled or disassembled parts.

As specified in the procedure, the inspection is accomplished by inducing a magnetic field in the part and applying a

liquid suspension of iron oxide particles to the surface to be inspected. By controlling the direction of the magnetic flux,

the lines of magnetic force shall be positioned perpendicular to the crack or flaw. All magnetic particle inspections in this

manual shall be of the wet continuous method using fluorescent magnetic particles.

1.4.8.1 Magnetic Particle Inspection Equipment. Considerations involved in the selection of magnetic particle inspection

equipment include the type of magnetizing current and the location and nature of the inspection. The purpose of this

manual is to support the accomplishment of NDI at the AVUM and AVIM levels. This dictates equipment that can be

used on or off the helicopter at remote sites. Therefore, magnetic particle procedures in this manual use the

electromagnetic yokes or probes and hand-held coils as shown in Figure 1-6. This equipment is common and readily

available to AVUM and AVIM levels. Stationary magnetic particle equipment can be used if facilities, required shop

equipment, and qualified NDI technicians are available. Refer to TM 55-1500-335-23 (Nondestructive Inspection

Methods manual) for stationary magnetic particle inspection techniques.

1-32
TM 1-1520-264-23

Figure 1-6. Portable Magnetic Particle Inspection Equipment

1-33
TM 1-1520-264-23

1.4.8.1.1 Magnetic Yokes and Probes. Portable induced field inspection equipment is generally referred to as either a

probe or a yoke. These terms are synonymous and differ due to manufacturer's nomenclature. They are small, portable,

easy to use, and can be used on or off the helicopter. They induce a strong magnetic field into that portion of a part that

lies between the poles or legs. This limits the magnetization to longitudinal; however, by turning the probe 90° on the

part for the second position, circular and longitudinal magnetization to the axis of the part has been produced. Some

yokes and probes have both AC and DC capabilities while others have AC only. All procedures in this manual use AC.

AC provides a very desirable and useful field. The vibratory action of AC adds significantly to the magnetic particle

mobility enhancing the formation and build-up of larger and sharper indications at discontinuities. An AC magnetic field

is also used when it is necessary to reveal only surface cracks, common to in-service parts due to fatigue and stress

cracking. Yokes and probes utilizing AC for magnetization also have the additional advantage that they can be used for

demagnetization.

1.4.8.1.2 Hand-held Coil. For longitudinal magnetization of bolts, shafts, spindles, axles, and similar small parts, the

hand-held coil offers a simple, convenient method of inspecting for transverse cracks. It allows for equipment

maintenance inspections wherever a coil can be applied around the part. Parts are magnetized and demagnetized with

the same coil.

1.4.8.2 Safety Precautions During Magnetic Particle Inspections. Follow safety precautions and instructions contained in

this manual and the Nondestructive Inspection Methods manual listed in Table 1-1.

• Black lights generate considerable heat during use. Extreme care must be exercised to prevent contacting 

the housing with any part of the body.

• To prevent injury to eyes, do not look directly into black light.

• Prolonged direct exposure of hands to the filtered black lights main beam may be harmful. Suitable gloves 

should be worn when exposing hands to the main beam.

a. Follow manufacturer's instructions when using black lights and filter.

b. Do not wear sunglasses or glasses with light-sensitive lenses during fluorescent magnetic particle inspections. 

They can contribute to improper interpretation of defects.

CAUTION

Do not operate magnetic particle equipment within 36 inches of aircraft instruments.

1.4.9 Demagnetization of Inspection Parts. Following magnetic particle inspection of a part, the residual magnetic field

in the part shall be reduced to the lowest possible level. This must be done prior to returning the part to service or

rejecting it as a defective part. Unless this is done properly, the residual magnetism may cause adverse influence on

instruments, unnecessary wear on parts, or attract ferrous metal chips and dust into bearing surfaces. After

demagnetization a magnetic field strength meter shall be used to measure residual fields. Readings in excess of three

units are not acceptable.

1-34
TM 1-1520-264-23

1.4.9.1 Demagnetization Using AC. If AC demagnetization is selected, hold the part about 12 inches in front of the coil.

Move it slowly and steadily through the coil to at least 36 inches beyond the end of the coil while current is still flowing.

Repeat process as necessary. Rotate and tumble parts of complex configuration while passing through the coil field. All

parts can be demagnetized using a contour probe in the AC mode. Place the probe against the magnetized part with the

switch in AC position. Turn probe on and withdraw it from the part, or the part from the probe, about 24 inches before

turning the probe off.

1.4.9.2 Demagnetization Using DC. If DC demagnetization is selected, the initial demagnetizing field shall be higher

than, and in nearly the same direction as, the field reached during inspection. The field shall then be reversed and

decreased in magnitude, and the process repeated (cycled) until an acceptable low value of residual field is reached.

Whenever possible, parts that have been circularly magnetized shall be magnetized in the longitudinal direction before

being demagnetized. This procedure is limited to stationary equipment.

1.4.10 Radiographic (RT) Method.

NOTE

Radiographic inspection shall be performed in accordance with the general application and techniques in TM 55-1500-

335-23 (Nondestructive Inspection Methods manual) and the specific requirements of this technical manual.

Radiographic inspection is used to detect internal and external structural details of all types of parts and materials. This

method is used for the inspection of airframe structure for damage, detection of moisture entrapment, structure

alignment, and foreign object intrusion. It can sometimes be used in areas otherwise inaccessible to other

nondestructive inspections and to verify indications observed by other methods.

Radiographic inspections are accomplished by passing the X-ray beam through the part or assembly to expose a

radiographic film emulsion or other sensitized medium. The processed film shows the structural details of the part by

variations in film density. Requirements for film density, image quality indicator, identification, and other factors are

specified in MIL-STD-453.

Film processing is a series of operations such as developing, fixing, and washing, associated with the conversion of the

latent image into a stable visible image and will be provided by manual or automatic film processing.

1.4.10.1 Safety Precautions During Radiographic Inspections. Follow safety precautions and instructions contained in

this manual and the Nondestructive Inspection Methods manual listed in Table 1-1.

1-35
TM 1-1520-264-23

Radiation Hazard

Assure compliance with all applicable precautions set forth in TM 55-1500-335-23 (Nondestructive

Inspection Methods manual) listed in Table 1-1. A hazard associated with exposure to ionizing radiation

is that serious injury can be inflicted without pain, burning, or other sense of discomfort during the

exposure period. Radiation protection shall be utilized in accordance with AR40-14/DLAR 1000.28.

1.4.10.2 Mixing of Radiographic Film Processing Chemicals. Exercise extreme care when working with film processing

chemicals. Fixer solution is highly acidic and developer is highly caustic. Avoid contact with the skin. Flush any skin

contact with water.

1.4.11 Eddy Current (ET) Method.

NOTE

Eddy current inspections shall be performed in accordance with the general application and techniques in

TM 55-1500-335-23 (Nondestructive Inspection Methods manual) and the specific requirements of this

technical manual.

The eddy current method is used for the detection of discontinuities in electrically conductive materials. The method is

effective when inspecting for discontinuities originating: (1) at the radii of mounting lugs, flanges, or crevices; (2) at

pressed-in (interference fit) grease fittings, guide pins, etc.; and (3) from fastener holes and bushing/bearing bores. Eddy

current method will locate surface cracking on any conductive material, but probes and techniques for inspection of

magnetic materials may differ considerably from those used on nonferromagnetic materials.

Eddy current has great value for inspecting areas where paint stripping is not desirable and/or impossible. The method

also has wide application in confirming surface indications found by other methods.

The capability and reliability of the eddy current method has been greatly enhanced by the use of modern phase analysis

(impedance plane display) instruments used in conjunction with shielded probes. These instruments display a

representation of the impedance plane which illustrates both the magnitude and direction of impedance changes.

Impedance variables (conductivity, probe lift-off, permeability variations, etc.) can be separated by their characteristic

video response and are readily recognized by the trained operator. The interaction of the probe coils and the part is

represented by a "flying spot' (or dot) in the video display.

Equipment is standardized on a test block (reference block) which is constructed of a known material that contains known

good areas, and either simulated or actual defects of known size. The response of the equipment (eddy current machine

and probe) to the good material is set as the starting point by nulling the equipment on the sound area of the block. By

this action, all subsequent readings represent deviations from the null point and have both magnitude and direction.

Careful manipulation of the controls allows the operator to separate the response (deviation from the null point) for lift-off

and flaw (geometric) effects.

1-36
TM 1-1520-264-23

Shielded probes have a cylinder of material which encircles the coil of the probe. This. serves to constrict the probes

field and, therefore, limits the spread of eddy currents from much beyond the probe's diameter. This concentrated

electrical field is most useful for scanning around fasteners, near edges, and into specific small areas. Other types of

probes are used for wide area scans, alloy sorting, conductivity comparisons, coating thickness comparisons, skin

thickness comparisons, etc.

1.4.11.1 Safety Precautions During Eddy Current Inspection. Follow safety precautions and instructions contained in this

manual and the Nondestructive Inspection Methods manual listed in Table 1-1.

Electrical equipment shall not be operated in areas where combustible gases or vapors may be present,

unless the equipment is explosion-proof.

1.4.11.2 Eddy Current Scanning Techniques. Eddy current inspection is performed by moving the probe over and as

close as possible to the surface of the area of interest. If the coil(s) pass over a defect like a crack, the impedance of the

coil will change and be represented as a movement of the "flying spot." Before beginning the inspection, the operator will

have separated the response from lift-off and from a flaw by using the test block and manipulating the controls.

Therefore, the crack response will be essentially similar to the response from the known defect and different from the

response from lift-off. Microprocessor controlled instruments have the ability to store responses in memory. Such stored

responses are an invaluable teaching aid.

1.4.11.2.1 Scanning Around Fasteners, Inserts, and Edges of Parts. Shielded probes are recommended any time that

the pattern the eddy current field is likely to extend out such that it comes in contact with a feature which would mask the

response from a defect. Such features may include edges, fasteners, dissimilar materials attached to the test piece, etc.

An unshielded probe can be used around such features, but the effect of those features must be made constant by

keeping the distance between the probe and the feature constant. Non-conductive mechanical guides (straight edges,

plugs, spacers, etc.) can be used to maintain a constant distance. In fact, the use of non-conductive mechanical guides

is useful for shielded and unshielded probes alike. As operators gain experience, they become quite innovative in

making guides that maintain constant lift-off, angles, and distance from features which may mask flaw indications.

Common materials for mechanical guides are plastic (polyethylene, acrylic, and polycarbonate), wood, phenolic

impregnated mask (masonite), and resins for casting into shapes (epoxy, polyester, or hot glue). Careful selection of

probes and construction of suitable mechanical guides will make possible inspection of problem areas such as sharp

edges, tight radii, small openings, and areas near potentially masking features.

1.4.11.2.2 Bolthole Inspection. Manual bolthole inspection probes usually consist of a split 90 degree probe with the

exposed shaft inserted in an adjustable collar. The shaft is marked in increments and the collar secured at the desired

increment by means of a set screw through the collar. The probe is then rotated 360 degrees around the hole at each

setting until the entire surface of the bore has been inspected. These probes are available in federal or commercial

catalogs or can be locally manufactured. (Refer to TM 55-1500-335-23.)

1.4.11.2.3 Scanning Fillets and Radii. Using appropriate radius probe, scan fillets and radii several times in each

direction.

1-37
TM 1-1520-264-23

1.4.11.3 Eddy Current Instrument Standardization. Eddy current inspection equipment and standards required by the

procedures in this manual are listed in Table 1-7. Reference blocks, instrument settings, and standardization instructions

for the eddy current instrument, are included in each eddy current procedure. Instrument settings, as they are given in

this manual, should be considered typical and present a test block display shown in Figure 1-7. Additional nulling will be

required to reestablish the position of the "flying spot' with the probe on the part/area to be inspected. (Use Teflon tape

listed in Table 1-8 on the probe to reduce wear. Instrument settings shall be made with Teflon tape on the probe, if

used.)

1.4.11.4 Sorting Metal Using Eddy Current. In addition to the more common usage for crack detection, eddy current

equipment may be used for metal sorting. Electrical conductivity and magnetic permeability are the material

characteristics evaluated during this type inspection. The sorting technique cannot directly identify alloy or even the type

of metal. But when there are limited possibilities, conductivity and/or permeability information may permit proper

classification (see Figure 1-8). Typically the need for alloy sorting occurs when changes to parts are made to improve

performance. For example, a magnesium part that is experiencing severe corrosion is replaced by one made from

aluminum. Another example is the replacement of one aluminum part with another, also of aluminum, but made from an

alloy having improved strength or corrosion resistance. In both these examples, there may be a need to verify that

replacement has been made, and the electrical conductivity of the alloys involved may be sufficiently different to permit

verification by a sorting inspection. Another situation is the requirement to NDI a part to confirm a visual indication where

the material is not known and cannot be easily determined. Eddy current sorting will quickly determine if the part is

ferromagnetic and should be inspected using the magnetic particle method. Also, if the part is nonferromagnetic, which

test block (standard) most closely matches the conductivity of the part and, therefore, should be used to adjust the eddy

current equipment for crack inspection/verification.

1.4.12 Ultrasonic (UT) Method.

NOTE

Ultrasonic inspection shall be performed in accordance with the general application and techniques in TM

55-1500-335-23 (Nondestructive Inspection Methods manual) and the specific requirements of this

technical manual.

Ultrasonic inspection uses high frequency sound waves as a probing medium to provide information as to the state of

various materials. This method is effective for the inspection of most metals for surface and subsurface damage. The

method requires that at least one surface of the part be accessible for transducer contact in the vicinity of the area to be

examined. The inspection is accomplished by inducing the ultrasound into the part by coupling the transducer to the part

and picking up reflections of this sound from within the part. Any marked changes in acoustic properties: defect,

interface, or back surface will reflect sound back to the transducer. The detected ultrasonic reflections are electronically

displayed on a CRT and interpreted for indications of defects. Accessory wedges can be used to provide adequate

transducer mating to curved surfaces, change the angle, and/or the mode of propagation of the sound beam.

1.4.12.1 Safety Precautions During Ultrasonic Inspection. Follow safety precautions and instructions contained in this

manual and the Nondestructive Inspection Methods manual listed in Table 1-1.

1-38
TM 1-1520-264-23

Figure 1-7. Signatures of EDM Notches in Test Block

1-39
TM 1-1520-264-23

Figure 1-8. Typical Metal Sorting Display

Electrical equipment shall not be operated in areas where combustible gases or vapors may be present,

unless the equipment is explosion-proof.

a. If instrument is operated using AC power, use a grounded power cord.

b. Turn power OFF before connecting or disconnecting transducer cable or power cable.

1.4.12.2 Ultrasonic Instrument Standardization. The ultrasonic instrument used in ultrasonic inspection procedures

described throughout this manual is listed in Table 1-7. Reference blocks, instrument settings, and standardization

instructions for the ultrasonic instrument are included in the individual ultrasonic inspection procedures. Because of

varied circumstances under which the inspections may be performed, instrument settings, as they are given in this

manual, should be considered typical. Slight adjustment to the settings may be necessary to achieve the desired CRT

presentation. Illustrations representing typical. CRT presentation will, in most cases, include reference signals

representing initial pulse, transducer, and/or wedge echoes that have been moved off the scope to make room for

relevant indications. An effective ultrasonic inspection will depend largely upon the proper handling of the transducer;

therefore, the following steps are recommended:

1-40
TM 1-1520-264-23

a. Clean ultrasonic transducer with a low-lint cloth, MIL-C-85043 or equivalent Clean all contact surfaces when 

using a wedge or delay block. Apply couplant to these contact surfaces and carefully tighten the assembly prior 

to test.

NOTE

Scratches or similar surface blemishes remaining on the transducer or wedge may give false indications.

b. Use prescribed or equivalent couplant and in sufficient quantity to achieve proper coupling. The use of lubricants

containing graphite, silicones, and glycerines is prohibited.

c. Apply adequate pressure to keep transducer in contact with part.

d. Use moderate speed for transducer search pattern. If transducer movement is too fast, a flaw could be passed 

over without a proper indication.

1.4.13 Acceptance/Rejection Criteria.

CAUTION

Misinterpretation of indications can result in rejectable parts being accepted and

acceptable parts being rejected. Only NDI personnel trained and qualified in accordance

with applicable military standards and technical manuals shall perform and interpret

nondestructive inspections.

Nondestructive inspection procedures in this manual have been selected to enhance the safety of the aircraft and

personnel. Inspection procedures (including primary and backup) have been outlined to enable NDI personnel to perform

a reliable inspection of parts with respect to their design, composition, and accessibility. In the event that a final

interpretation of an indication cannot be made, assistance from the next higher maintenance level shall be requested.

1.4.14 Equipment Used for NDI. Refer to Table 1-7 for a summary of equipment used for NDI in this manual.

Equivalent equipment may be used unless specified otherwise in the inspection procedures.

1.4.15 Materials Used for NDI. Refer to Table 1-8 for a summary of materials used for NDI in this manual. Common

commercial grade materials (cheesecloth, paper, etc.) are not listed. Equivalent materials may be used unless specified

otherwise in inspection procedures.

1.4.16 Post Cleaning and Restoration of Part or Area After NDI. Upon completion of the NDI test and prior to restoration

of protective finishes, it is necessary to clean off residual inspection materials from the part. This cleaning will vary

based upon test method, contaminant, and subsequent processing of the part. In many instances, methods used for

precleaning are acceptable for post cleaning. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

1-41
TM 1-1520-264-23

Table 1-7. Equipment Used for NDI

Fluorescent Penetrant Fluorescent Penetrant Inspection Kit

Method Black Light UV Kit

Black Light Meter

Black Light Bulbs

Filter UV

Magnetic Particle Method Yoke and Coil Kit

Black Light

Magnetic Particle Inspection Probe

Magnetometer

Eddy Current Method Eddy Current Inspection Unit

Cable Assembly, Coaxial 6-feet long (1 required)

Reference Block Aluminum (0.008, 0.020, and 0.040

EDM notches)

Reference Block Titanium (0.008, 0.020, and 0.040

EDM notches)

Reference Block Magnesium (0.008, 0.020, and

0.040 EDM notches)

Reference Block - Block of Six Conductivity Samples

Probe, right angle, shielded surface 100 KHz-500 KHz

90° 1/2 inch drop

Probe, straight, shielded surface 100 KHz-500 KHz

Ultrasonic Method Ultrasonic Inspection Unit

Cable Assembly, BNC to microdot

Bond Testing Method Bond Test Inspection Unit

Cable Assembly

Probe, Mechanical Impedance Analysis

Probe Holder, spring loaded

Test Block, Composite Defect Standard #1

Test Block, Composite Defect Standard #3

Test Block, Aluminum Honeycomb with 0.020 inch

thick aluminum/fiberglass skin (refer to Appendix C)

Test Block, Aluminum Honeycomb with 0.040 inch

thick aluminum skin (refer to Appendix C)

Test Block, Aluminum Honeycomb with 0.063 inch

thick aluminum skin (refer to Appendix C)

Radiographic Method Tripod X-Ray Tubehead Stand

Signal Appliance Lamp Assembly

X-Ray Unit (LPX-160 Water Cooled Digital)

Film Processor

Note: Refer to Appendix B for equipment part number, national stock number, and manufacturer.

1-42
TM 1-1520-264-23

Table 1-8. Materials Used for NDI

P/N or National Stock

Nomenclature Specification Manufacturer Number

Fluorescent Penetrant

Method

Type I, Method C MIL-1-25135 General Services 6850-01-703-7406

Administration (GSA)

Magnetic Particle

Method

Fluorescent Magnetic 14AM Magnaflux Div. of Illinois 6850-00-841-1347

Inspection Tool Works Inc.

Compound 1301 W. Ainsle St.

Chicago, IL 60656

Eddy Current Method

Tape, Teflon MIL-I-23594 General Service 5970-00-812-7387

Administration (GSA)

Ultrasonic Method

Couplant, Ultrasonic Ultragel II Sonotech, Inc. 6850-01-157-4348

1413 Frasier St.

Suite 2, Bldq. H

P.O. Box 2189

Bellingham, WA 98226

Bond Test Method

Tape, Teflon MIL-1-23594 General Service 5970-00-813-7387

Administration (GSA)

Radiographic Method

M-2 Film, Ready Pack 145 7837 Eastman Kodak Co. 6635-00-412-2071

8 inch x 10 inch 343 State St.

Rochester, NY 14650

M-2 Film, Ready Pack 145 8926 Eastman Kodak Co. 6635-00-838-9116

14 inch x 17 Inch 343 State St.

Rochester, NY 14650

1-43
TM 1-1520-264-23

Table 1-8. Materials Used for NDI - Continued

P/N or National Stock

Nomenclature Specification Manufacturer Number

Radiographic Method -

continued

AA-2 Film, Ready Pack 145 92Q5 Eastman Kodak Co. 6635-00-850-3321

14 inch x 17 inch 343 State St.

Rochester, NY 14650

AA-2 Film, Ready Pack 827 8137 Eastman Kodak Co. 6635-00-850-3326

8 inch x 10 inch 343 State St.

Rochester, NY 14650

Miscellaneous Materials

Gloves, Protective ZZ-G-381 General Services 8415-00-823-7456

Administration (GSA)

Gloves, Surgeon E-008 Defense Services 1615-01-149-8843

Administration (DSA)

Apron, General Purpose A-A-55063 General Services 8415-00-082-6108

Administration (GSA)

Face Shield A-A-1770 General Services 4240-00-542-2048

Administration (GSA)

Cloth, Low-Lint Cleaning MIL-C-85043 General Services 7920-00-044-9281

Administration (GSA)

Dry-Cleaning Solvent P-D-680, Type II General Services 6850-00-274-5421

Administration (GSA)

Cleaning Solvent MIL-C-38736 General Services 6850-00-538-0929

Administration (GSA)

Scotch-Brite, Type A L-P-0050 General Services 7920-00-659-9175

Administration (GSA)

1-44
TM 1-1520-264-23

Table 1-8. Materials Used for NDI - Continued

P/N or National Stock

Nomenclature Specification Manufacturer Number

Temporary Marking

Materials

Aircraft Marking MIL-P-83953 General Services 7510-00-537-6930

Pencils (China Yellow Administration (GSA)

Marker)

Prolonged breathing of vapor from organic solvents, degreasers, or paint thinners is

dangerous. Use respirators in confined areas per Occupational and Environmental

Health Respiratory Protection Program (TB MED 502 (DLAM 1000.2)). Have adequate

ventilation. Avoid prolonged skin contact. Wear rubber gloves and goggles.

a. Following all magnetic particle inspections, clean part by dipping or spraying with dry-cleaning solvent, P-D-680,

Type II. Wipe dry with a clean, low-lint cloth, MIL-C-85043, or equivalent.

b. After post cleaning has been performed, the original protective finish or approved alternate must be restored to

the part or area by appropriate personnel. Refer to applicable technical manuals listed in Table 1-1.

1-45/(1-46 blank)
TM 1-1520-264-23

SECTION II

ROTOR SYSTEM

2. GENERAL.

2.1 CONTENTS. The rotor system inspection items covered in this section are those critical items of the AH-64A

helicopter rotor blades, rotor head, and components listed in the Rotor System Inspection Index (Table 2-1).

Corresponding inspection figures and applicable text paragraphs are listed opposite each inspection item. The index

number for each item may be used to locate it in Figure 2-1.

Table 2-1. Rotor System Inspection Index

Index Inspection Paragraph Figure

Number Nomenclature Method Number Number

2 Main Rotor Droop Stop Follower (Plunger) PT 2.2 2-2

3 Droop Stop Ring MT 2.3 2-3

*4 Main Rotor Blade (Voids) BT 2.4 2-4

*5 Main Rotor Blade PT 2.5 2-5

*6 Main Rotor Blade RT 2.6 2-6

7 Main Rotor Blade Weight Support Fittings ET 2.7 2-7

*8 Main Rotor Mast MT 2.8 2-8

9 Main Rotor Mast Retaining Ring MT 2.9 2-9

*10 Main Rotor Hub Retention Nut MT 2.10 2-10

*11 Main Rotor Head (Hub) ET 2.11 2-11

*12 Main Rotor Lead Lag Link (Damper Link) ET 2.12 2-12

13 Main Rotor Damper ET 2.13 2-13

14 Main Rotor Damper Trunnion ET 2.14 2-14

*15 Main Rotor Damper Rod End MT 2.15 2-15

*16 Main Rotor Pitch Housing ET 2.16 2-16

*17 Main Rotor Feathering Bearing Housing ET 2.17 2-17

18 Main Rotor Striker Plate and Shims MT 2.18 2-18

*19 Main Rotor Hub Bearing ET 2.19 2-19

*20 Main Rotor Lower Shoe ET 2.20 2-20

*21 Main Rotor Head Hub Load Plate MT 2.21 2-21

22 Main Rotor Hub Brackets MT 2.22 2-22

2-1
TM 1-1520-264-23

Table 2-1. Rotor System Inspection Index - Continued

Index Inspection Paragraph Figure

Number Nomenclature Method Number Number

*23 Main Rotor Hub Lower Plate MT 2.23 2-23

*24 Tail Rotor Fork Assembly (Head and Teeter ET 2.24 2-24

Stop)

*25 Tail Rotor Blade PT 2.25 2-25

*26 Tail Rotor Blade (Voids) BT 2.26 2-26

*27 Tail Rotor Blades (Fluid) RT 2.27 2-27

*28 Tail Rotor Hub ET 2.28 2-28

29 Tail Rotor Clamps and Locking Plates ET 2.29 2-29

NOTE: *Indicates Flight Safety Part.

2-2
TM 1-1520-264-23

NDI_AH-64_F2_1_1

Figure 2-1. Rotor System (Sheet 1 of 2)

2-3
TM 1-1520-264-23

NDI_AH-64_F2_1 _2

Figure 2-1. Rotor System (Sheet 2 of 2)

2-4
TM 1-1520-264-23

2.2 MAIN ROTOR DROOP STOP FOLLOWER (PLUNGER) (PT).

2.2.1 Description (Figure 2-1. Index No. 2). The main rotor droop stop follower (plunger) contacts the droop stop ring

to limit the pitch housing downward movement when the main rotor blade assembly is stopped.

2.2.2 Defects. This inspection is used to verify crack indications found visually on the main rotor droop stop follower

(plunger). No cracks are allowed.

2.2.3 Primary Method. Fluorescent Penetrant.

2.2.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-1-25135

level 3 penetrant materials shall be selected from the approved list in Table 1-8.

2.2.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection for

cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of the

installed part using this procedure. If required, the main rotor droop stop follower (plunger) shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

2.2.3.3 Access. Not applicable.

2.2.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

2.2.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,

paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 2-2.

2.2.3.6 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

2.2.4 Backup Method. None required.

2.2.5 System Securing. Clean the main rotor droop stop follower (plunger) to remove inspection media. Refer to Post

Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor droop stop follower (plunger), if

removed, requires installation in accordance with the applicable technical manuals listed in Table 1-1.

2.3 DROOP STOP RING (MT).

2.3.1 Description (Figure 2-1. Index No. 3). The main rotor droop stop ring provides the contact surface for the droop

stop follower to limit downward movement when the main rotor blade assembly is stopped.

2.3.2 Defects. This inspection is used to verify crack indications found visually on the main rotor droop stop ring. No

cracks are allowed.

2.3.3 Primary Method. Magnetic Particle.

2-5
TM 1-1520-264-23

NDI_AFH64_F2_2

Figure 2-2. Main Rotor Droop Stop Follower (Plunger)

2-6
TM 1-1520-264-23

2.3.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

2.3.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection for

cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of the

installed part using applicable positions of this procedure. If required, the main rotor droop stop ring shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

2.3.3.3 Access. Not applicable.

2.3.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.3.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

2.3.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The position required for this inspection is illustrated in Figure 2-3.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media 

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

2.3.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

2.3.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

2.3.4 Backup Method. None required.

2.3.5 System Securing. Clean the main rotor droop stop ring thoroughly to remove all residual magnetic particle

media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16.The main rotor droop stop

ring, if removed, requires installation in accordance with the applicable technical manuals listed in Table 1-1.

2-7
TM 1-1520-264-23

ND AH-4_F2_3

Figure 2-3. Droop Stop Ring

2-8
TM 1-1520-264-23

2.4 MAIN ROTOR BLADE (VOIDS) (BT).

2.4.1 Description (Figure 2-1. Index No. 4). The main rotor blade assemblies are rotating airfoils with swept tips that

are constructed of stainless steel and fiberglass. Each attaches to the main rotor head assembly by a lead lag link and a

blade attachment pin.

2.4.2 Defects. Void damage can occur anywhere on both sides of the blade shown in Figure 2-4.

NOTE

A void is defined as an unbonded area that is supposed to be bonded. Many subdefinitions are given,

such as lack of adhesive, gas pocket, misfit, etc. However, this manual makes no distinction among

these, instead grouping them all under one general term ("void").

2.4.3 Primary Method. Bond Testing.

2.4.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Bond Test Unit

b. Probe, Mechanical Impedance Analysis

c. Probe Holder

d. Cable Assembly

e. Test Block, metal honeycomb with skin thickness closest to that of the panel to be inspected

f. Test Block, Composite Defect Standard #1

g. Teflon Tape, refer to Table 1-8

h. Aircraft Marking Pencil, refer to Table 1-8

2.4.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance in accordance with the

applicable technical manuals listed in Table 1-1.

2.4.3.3 Access. Not applicable.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands

and restraint equipment when working above 10 feet on helicopter in a nontactical

environment. Otherwise, personnel injury could result from accidental falls.

2.4.3.4 Preparation of Part. The main rotor blades shall be thoroughly cleaned. Refer to Preparation of Part or Area for

NDI, paragraph 1.4.4.

2-9
TM 1-1520-264-23

Figure 2-4. Main Rotor Blade (Voids)

2.4.3.5 NDI Equipment Settings. Refer to Bond Test Equipment, paragraph 1.4.6.1.

a. Attach cable and probe to Bondmaster. Protect probe with Teflon tape and install in probe holder.

b. Turn on Bondmaster, press SPCL, and make the following adjustments:

H Pos - 40%

V Pos - 80%

PHASE REF - 0

DRIVE - MID

c. Press SET and select DISPLAY - PHASE.

d. Place probe on the good area of test blocks and press GOOD PART. Do this several times while moving the

probe to different spots in the good area of the standard. Note the video signature for each. Select and enter a

representative good area by pressing GOOD PART one last time.

e. Place probe on void area of test block and press BAD PART. Do this several times while moving the probe

slightly to different positions within the void area. Select and enter a position that gives a strong difference

between good and void areas. Use DIFF soft key to observe difference between good and bad areas of test

block.

2-10
TM 1-1520-264-23

NOTE

If, during setup, the flying spot deflects upward or to the side when the probe passes

over the bad part instead of the desired down deflection toward the alarm box, press

SPCL and toggle to a different phase setting (90, 180, or 270), and repeat steps d. and

e. Continue to try phase setting until the flying spot moves in the desired down direction.

f. Place probe on good area of test block and press RUN. Flying spot should be near the top-center of the ACTIVE

screen. If not, press NULL. Slide probe from good to void area and note response from flying spot. This

response should provide both amplitude (vertical) and phase (horizontal) movement. The default gate/alarm

setting may be incorrect for this setup. Turn off or reset gate/alarm as desired.

g. The Bondmaster is programmed to automatically set test parameters to a start-up or initial bond test. By

following the steps outlined above, adjustments to the FREQ, GAIN, and ALARM can help to refine the

selectivity in locating defects among differing composite materials.

2.4.3.6 Inspection Procedure. Refer to Bond Test Method, paragraph 1.4.6 and inspection areas shown in Figure 2-4.

a. Skin-to-Honeycomb Voids. Place probe on main rotor blade in location where test for skin-to-honeycomb bond

separation is desired and press NULL. Move probe from good to suspect area and note response. A strong

amplitude change and phase shift similar to the standard is indicative of a void. This setup is very sensitive to

thin skin-to-core bonding. Move probe slowly over the skin and note the slight amplitude change (bounce) as the

probe senses alternately the honeycomb cell nodes and cell walls.

NOTE

The basic setup provided above also selects a frequency that provide a satisfactory

inspection for voids associated with skin-to-spar, skin-to-trailing edge, doubler-todoubler and doubler-to-skin, and trim tab bonding.

b. Use the NULL and GAIN adjustments to reset the ACTIVE screen for the areas to be inspected (do not go back

to SET mode). Also, compare similar areas. For example, to check for spar to skin voids, check front and back

of blade in the same area, or check another blade in the same area. Observe that, when moving the probe

chordwise from the spar to the trailing edge, the transitions at the spar-to-honeycomb and the honeycomb-totrailing edge strip are easily detected. When inspecting these areas, adjust the NULL and GAIN and move the

probe carefully along the transition using a straight edge or other guide. A localized phase and amplitude shift

similar to the test block indicates a void.

2.4.3.7 Marking and Recording of Inspection Results. Mark and record as required by paragraph 1.3.

NOTE

Attention shall be directed to accurately mark the boundaries of all voids. These

markings will be needed to determine acceptance or rejection criteria in accordance with

applicable technical manuals.

2-11
TM 1-1520-264-23

2.4.4 Backup Method. None required.

2.4.5 System Securing. None required.

2.5 MAIN ROTOR BLADE (PT).

2.5.1 Description (Figure 2-1. Index No. 5). The main rotor blade assemblies are rotating airfoils with swept tips that

are constructed of stainless steel and fiberglass. Each attaches to the main rotor head assembly by a lead lag link and a

blade attachment pin.

2.5.2 Defects. This inspection is used to verify crack indications found visually on the main rotor blade. No cracks are

allowed.

2.5.3 Primary Method. Fluorescent Penetrant.

2.5.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-1-25135

level 3 penetrant materials shall be selected from the approved list in Table 1-8.

2.5.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection for

cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of the

installed part using this procedure. If required, the main rotor blade shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

2.5.3.3 Access. Not applicable.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands

and restraint equipment when working above 10 feet on helicopter in a nontactical

environment. Otherwise, personnel injury could result from accidental falls.

2.5.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

2.5.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,

paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 2-5.

2.5.3.6 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

2.5.4 Backup Method. None required.

2.5.5 System Securing. Clean the main rotor blade to remove inspection media. Refer to Post Cleaning and

Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor blade, if removed, requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

2-12
TM 1-1520-264-23

Figure 2-5. Main Rotor Blade

2.6 MAIN ROTOR BLADE (RT).

2.6.1 Description (Figure 2-1. Index No. 6). The main rotor blade assemblies are rotating airfoils with swept tips that

are constructed of stainless steel and fiberglass. Each attaches to the main rotor head assembly by a lead lag link and a

blade attachment pin.

2.6.2 Defects. Water in the honeycomb core.

2.6.3 Primary Method. Radiography.

Radiation Hazard

Assure compliance with all applicable safety precautions set forth in TM 55-1500-335-23

(Nondestructive Inspection Methods manual) listed in Table 1.1. A hazard associated

with exposure to ionizing radiation is that serious injury can be inflicted without pain,

burning or other sense of discomfort during the exposure period. Radiation protection

shall be utilized in accordance with AR40-14/DLAR 1000.28.

2.6.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

2-13
TM 1-1520-264-23

a. X-ray Unit

b. Tripod, X-ray tubehead stand.

c. Film Processor

d. Film, Ready Pack 14 inch x 17 inch

e. Marking Material, refer to Table 1-8

2.6.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. Partial inspection for

cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of the

installed part using-this procedure. If required, the main rotor blades shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

2.6.3.3 Access. Not applicable.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands

and restraint equipment when working above 10 feet on helicopter in a nontactical

environment. Otherwise, personnel injury could result from accidental falls.

2.6.3.4 Preparation of Part. The rotor blade shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.6.3.5 NDI Equipment Settings.

a. Refer to Radiographic (X-ray) method, paragraph 1.4.10.

b. Typical equipment settings, inspection, and exposure data are given in Figure 2-6.

2.6.3.6 Inspection Procedure. Inspect designated areas, refer to Figure 2-6 for typical fluid entrapment and source/film

placement.

a. Position film and desired nameplate data for exposure number 1.

b. Position X-ray tubehead for exposure number 1.

c. Set X-ray unit to the values given in the Radiographic Inspection Data chart for exposure number 1.

d. Make exposure number 1.

e. Remove exposed film.

f. Repeat inspection procedure (steps a. through e. above) for each exposure.

g. Process and interpret film for defects as noted in paragraph 2.6.2 and as shown in Figure 2-6.

2-14
TM 1-1520-264-23

Figure 2-6. Main Rotor Blade (Sheet 1 of 2)

2-15
TM 1-1520-264-23

LIGHT AREAS-FLUID IN HONEYCOMB

NDl_AH-64_F2_6_2

Figure 2-6. Main Rotor Blade (Sheet 2 of 2)

2-16
TM 1-1520-264-23

2.6.4 Backup Method. None required.

2.6.5 System Securing. The main rotor blade shall be cleaned as necessary. Refer to Post Cleaning and Restoration

of Part or Area after NDI, paragraph 1.4.1.6. The main rotor blade, if off the helicopter, requires reinstallation in

accordance with the applicable technical manual listed in Table 1-1.

2.7 MAIN ROTOR BLADE WEIGHT SUPPORT FITTINGS (ET).

2.7.1 Description (Figure 2-1. Index No. 7). The main rotor blade weight support fittings are located within the swept

back tip. The fitting supports the weight used when balancing the blade.

2.7.2 Defects. This inspection is used to verify crack indications found visually on the main rotor blade weight support

fitting. No cracks are allowed.

2.7.3 Primary Method. Eddy Current.

2.7.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)

g. Teflon Tape, refer to Table 1-8

h. Aircraft Marking Pencil, refer to Table 1-8

2.7.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection for

cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of the

installed part using this procedure in accordance with the applicable technical manuals listed in Table 1-1.

2.7.3.3 Access. Tip cap removed.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands

and restraint equipment when working above 10 feet on helicopter in a nontactical

environment. Otherwise, personnel injury could result from accidental falls.

2.7.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2-17
TM 1-1520-264-23

2.7.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - (56° aluminum) (30° titanium)

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

2.7.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-7.

Figure 2-7. Main Rotor Blade weight support Fittings

2-18
TM 1-1520-264-23

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.7.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 2.7.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

2.7.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as

required by paragraph 1.3.

2.7.4 Backup Method. None required.

2.7.5 System Securing. T he main rotor blade weight support fitting, if removed, requires installation in accordance

with the applicable technical manuals listed in Table 1-1.

2.8 MAIN ROTOR MAST (MT).

2.8.1 Description (Figure 2-1. Index No. 8). The main rotor mast provides the attachment point for the main rotor head

assembly.

2.8.2 Defects. This inspection is used to verify crack indications found visually on the main rotor mast. No cracks are

allowed.

2.8.3 Primary Method. Magnetic Particle.

2.8.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection ProbeNYoke

b: Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

2.8.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection for

cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of the

installed part using applicable positions of this procedure. If required, the main rotor mast shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

2-19
TM 1-1520-264-23

2.8.3.3 Access. Accessibility of the main rotor mast varies considerably. Refer to Figure 1-4 and Table 1-2 to locate

applicable access provisions.

2.8.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.8.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

2.8.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The position required for this inspection is illustrated in Figure 2-8.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in typical position as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

2.8.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

2.8.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

2.8.4 Backup Method. None required.

2.8.5 System Securing. Clean the main rotor mast thoroughly to remove all residual magnetic particle media. Refer to

Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor mast, if removed, requires

installation in accordance with the applicable technical manuals listed in Table 1-1.

2.9 MAIN ROTOR MAST RETAINING RING (MT).

2.9.1 Description (Figure 2-1, Index No. 9). The main rotor mast retaining ring secures the main rotor mast retention

nut to the main rotor mast.

2.9.2 Defects. This inspection is used to verify crack indications found visually on the main rotor

mast retaining ring. No cracks are allowed.

2.9.3 Primary Method. Magnetic Particle.

2-20
TM 1-1520-264-23

Figure 2-8. Main Rotor Mast

2-21
TM 1-1520-264-23

2.9.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

2.9.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main rotor

mast retaining ring removed in accordance with the applicable technical manuals listed in Table 1-1.

2.9.3.3 Access. Not applicable.

2.9.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.9.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

2.9.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the

orientation of possible cracks. Positions required for this inspection are illustrated in Figure 2-9.

Figure 2-9. Main Rotor Mast Retaining Ring

2-22
TM 1-1520-264-23

a. Select AC on the AC/DC power. switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

2.9.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

2.9.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

2.9.4 Backup Method. None required.

2.9.5 System Securing. Clean the main rotor mast retaining ring thoroughly to remove all residual magnetic particle

media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor mast

retaining ring, requires installation in accordance with the applicable technical manuals listed in Table 1-1.

2.10 MAIN ROTOR HUB RETENTION NUT (MT).

2.10.1 Description (Figure 2-1. Index No. 10). The main rotor hub retention nut secures the main rotor hub assembly to

the main rotor mast.

2.10.2 Defects. Defects can occur anywhere on the surface of the main rotor hub retention nut. No cracks are allowed.

2.10.3 Primary Method. Magnetic Particle.

2.10.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

2.10.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main rotor

hub retention nut shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

2.10.3.3 Access. Not applicable.

2-23
TM 1-1520-264-23

2.10.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.10.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

2.10.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. Positions required for this inspection are illustrated in Figure 2-10.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 2.10.3.8.

f. Repeat steps a. through e. for position 2.

2.10.3.7 Marking and Recording of. Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

Figure 2-10. Main Rotor Hub Retention Nut

2-24
TM 1-1520-264-23

2.10.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

2.10.4 Backup Method. None required.

2.10.5 System Securing. Clean the main rotor hub retention nut thoroughly to remove all residual magnetic particle

media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor hub retention

nut requires installation in accordance with the applicable technical manuals listed in Table 1-1.

2.11 MAIN ROTOR HEAD (HUB) (ET).

2.11.1 Description (Figure 2-1. Index No. 11). The main rotor head assembly is a fully-articulated assembly that

provides attachment points for the four main rotor blade assemblies.

2.11.2 Defects. This inspection is used to verify crack indications found visually on the main rotor head (hub). No

cracks are allowed.

2.11.3 Primary Method. Eddy Current.

2.11.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.11.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the main rotor head (hub) shall be removed in accordance

with the applicable technical manuals listed in Table 1-1.

2.11.3.3 Access. Not applicable.

2.11.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.11.3.5 NDI Equipment Settings.

2-25
TM 1-1520-264-23

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9ell.

Frequency F1 -200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe is

passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

2.11.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-11.

Figure 2-11. Main Rotor Head (Hub)

2-26
TM 1-1520-264-23

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.11.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 2.11.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

2.11.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

2.11.4 Backup Method. None required.

2.11.5 System Securing. The main rotor head (hub), if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

2.12 MAIN ROTOR LEAD LAG LINK (DAMPER LINK) (ET).

2.12.1 Description (Figure 2-1. Index No. 12). The four lead lag links are titanium mounts that provide a mounting point

for each of the main rotor blade assemblies.

2.12.2 Defects. This inspection is used to verify crack indications found visually on the lead lag ink (damper link). No

cracks are allowed.

2.12.3 Primary Method. Eddy Current.

2.12.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.12.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the lead lag link shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

2-27
TM 1-1520-264-23

2.12.3.3 Access. Not applicable.

2.12.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.12.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 30°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

2.12.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-12.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.12.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 2.12.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

2.12.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.12.4 Backup Method. None required.

2.12.5 System Securing. The lead lag link (damper link), if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

2-28
TM 1-1520-264-23

Figure 2-12. Main Rotor Lead Lag Link (Damper Link)

2-29
TM 1-1520-264-23

2.13 MAIN ROTOR DAMPER (ET).

2.13.1 Description (Figure 2-1. Index No. 13). Two dampers are attached between each pitch housing and its lead lag

link. The dampers are used to control the lead lag movement of the rotor blades and to prevent mass imbalance

(unequal blade spacing) and for main rotor blade phase adjustment.

2.13.2 Defects. This inspection is used to verify crack indications found visually on the main rotor damper. No cracks

are allowed.

2.13.3 Primary Method. Eddy Current.

2.13.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.13.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main rotor damper shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

2.13.3.3 Access. Not applicable.

2.13.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.13.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

V Pos - 20%

2-30
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

2.13.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-13.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.13.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 2.13.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

2.13.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.13.4 Backup Method. None required.

2.13.5 System Securing. The main rotor damper, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

2.14 MAIN ROTOR DAMPER TRUNNION (ET).

2.14.1 Description (Figure 2-1. Index No. 14). The main rotor damper trunnion provides the attachment point for the

main rotor damper to the main rotor pitch housing.

2.14.2 Defects. This inspection is used to verify crack indications found visually on the main rotor damper trunnion. No

cracks are allowed.

2.14.3 Primary Method. Eddy Current.

2.14.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2-31
TM 1-1520-264-23

Figure 2-13. Main Rotor Damper

2-32
TM 1-1520-264-23

2.14.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main rotor damper trunnion shall be removed in accordance with

the applicable technical manuals listed in Table 1-1.

2.14.3.3 Access. Not applicable.

2.14.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.14.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

2.14.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-14.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.14.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 2.14.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

2.14.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2-33
TM 1-1520-264-23

Figure 2-14. Main Rotor Damper Trunnion

2-34
TM 1-1520-264-23

2.14.4 Backup Method. None required.

2.14.5 System Securing. The main rotor damper trunnion, if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

2.15 MAIN ROTOR DAMPER ROD END (MT).

2.15.1 Description (Figure 2-1. Index No. 15). The main rotor damper rod end provides for attachment of the damper

assembly to the lead lag link.

2.15.2 Defects. This inspection is used to verify crack indications found visually on the main rotor damper rod end. No

cracks are allowed.

2.15.3 Primary Method. Magnetic Particle.

2.15.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

2.15.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using applicable positions of this procedure. If required, the main rotor damper rod end shall be

removed in accordance with the applicable technical manuals listed in Table 1-1.

2.15.3.3 Access. Not applicable.

2.15.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.15.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

2.15.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 2-15.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

2-35
TM 1-1520-264-23

Figure 2-15. Main Rotor Damper Rod End

2-36
TM 1-1520-264-23

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five

seconds.

d. Inspect for cracks using the black light.

2.15.3.7 Marking and Recording of Inspection Results. Mark and record the. inspection results as required by

paragraph 1.3.

2.15.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

2.15.4 Backup Method. None required.

2.15.5 System Securing. Clean the main rotor damper rod end thoroughly to remove all residual magnetic particle

media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor damper rod

end, if removed, requires installation in accordance with the applicable technical manuals listed in Table 1-1.

2.16 MAIN ROTOR PITCH HOUSING (ET).

2.16.1 Description (Figure 2-1. Index No. 16). The main rotor pitch housing assembly control inputs

to course angle changes on the main rotor blade assembly.

2.16.2 Defects. This inspection is used to verify crack indications found visually on the main rotor pitch housing. No

cracks are allowed.

2.16.3 Primary Method. Eddy Current.

2.16.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.16.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main rotor pitch housing shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

2.16.3.3 Access. Not applicable.

2.16.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2-37
TM 1-1520-264-23

2.16.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

2.16.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-16.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.16.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 2.16.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

2.16.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.16.4 Backup Method. None required.

2.16.5 System Securing. The main rotor pitch housing, if removed, requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

2-38
 TM 1-1520-264-23

 Change 1 2-38.1

2.16.1.1 STRAP PACK OUTBOARD BOLT INSPECTION (UT)

2.16.1.1.1 Description. The four strap pack outboard bolts are made of PH13-8 MO steel and

are secured by a pin to the lead lag link and pitch housing.

2.16.1.1.2 Defects. This inspection is used to detect inside and outside diameter

circumferential cracks in the shank of the strap pack bolt.

2.16.1.1.3 Primary Method. Ultrasonic specific.

NOTE

This inspection procedure and graphics shall be reviewed in its entirety prior to

performing the inspection. The supplemental training CD ROM should also be

reviewed in conjunction with performing this procedure.

2.16.1.1.3.1 NDI Equipment and Materials. (Refer to Appendix B)

a. Ultrasonic Inspection Unit, USD 15S/AF

b. Transducer, 15.0 MHz, longitudinal wave, 1/8 in. x 1/8 in. element

c. Transducer Positioner

d. Cable Assembly, BNC to Microdot

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

2.16.1.1.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground

maintenance. The lead lag link shall be removed in accordance with TM 1-1520-238-23.

2.16.1.13.3 Access. Access to the strap pack outboard bolt can be accomplished by removal

of the main rotor blade and the lead lag link in accordance with TM 1-1520-238-23.

2.16.1.1.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of

Part for NDI, paragraph 1.4.4.

Lead Lag Link

Pitch change housing

Strap Pack Outboard Bolt
TM 1-1520-264-23

2-38.2 Change 1

2.16.1.1.3.5 NDI Equipment Settings.

 a. Make the following initial settings on the Ultrasonic Inspection Unit, USD 15S:

(SETUP – DEFAULT SETTINGS) (BASICS)

DIALOG ENGLISH GAIN 58 dB

UNIT INCH RANGE 1.770 in

GAT-SEL Gate-A MTL VEL 233.0 in/ms

A-OUT amplit D-DELAY 0.00 in

A-LOGIC pos P-DELAY 0.00 ms

A-HORN on

A-ALARM short

(PULSER) (RECEIVER)

DAMPING 50 ohm FREQ 15 MHz

ASCAN NORMAL REJECT 0%

PRF-MOD AUTOLOW RECTIF FULL-W

PRF-VAL See Note 1 DUAL OFF

(GATES) (MEASURE)

GAT-SEL Gate-A GATE-SEL Gate-A

A-START 0.500 in. A-TOF peak

A-WIDTH 1.100 in. A-AMPLI %

A-THRSH 40% MEAS_VA none

(KEYS) See Note 2

(DATALOG) See Note 2

(ANGLE) See Note 2

(DAC) See Note 2

NOTES:

(1) WHEN THE PULSE REP FREQUENCY IS IN AN AUTOMATIC MODE, 

THE VALUE IS ELECTRONICALLY DETERMINED.

(2) NOT USED - LEAVE AT DEFAULT VALUES.

b. Refer to the Ultrasonic Method, paragraph 1.4.12. Calibrate the ultrasonic

instrument as follows:

NOTE

The transducer guide holes are a snug fit. Make sure the set screw is completely

backed out of the bore prior to inserting the transducer.
 TM 1-1520-264-23

 Change 1 2-38.3

(1) SET UP

(a) Attach the transducer and cable to the ultrasonic instrument.

(b) Apply a thin layer of couplant to the calibration standard bolt head

surface near the edge of the bore.

(c) Smooth the couplant with your finger to produce a uniform thin layer

around the bolt.

(d) Place the POSITIONER on the calibration standard and rotate it until

the “OD” guide hole is above the lower outside diameter EDM notch.

(e)Insert the TRANSDUCER in the OD guide hole until it bottoms.

Slowly rotate the POSITIONER to maximize the signal from the

notch. Reference Figure 1 for positioning, reference Figure 2 for

signal position on the CRT display.

 

Figure 1. Positioner/transducer placement

CL

ID OD

Transducer

Standard

S

Positioner
TM 1-1520-264-23

2-38.4 Change 1

(2) CALIBRATION

(a) With the transducer positioned from the SET UP procedure, adjust the

gain setting to achieve a signal 80% of full screen height (FSH) from the

lower OD EDM notch. Reference Figure 2 below.

 Figure 2. Lower OD EDM notch

(b) Rotate the POSITIONER off of the lower OD EDM notch. Slowly rotate

the transducer to minimize base line noise. Review Figures 2 and 3.

When the base line noise is minimized, carefully tighten the set screw.

Figure 3. Base line noise reduction

(c) Locate the POSITIONER over the upper OD EDM notch and adjust the

gain setting to achieve a signal 60 % FSH. Reference Figure 4.

Figure 4. Upper OD EDM notch

Lower OD

signal

noise

noise

Upper OD

signal
 TM 1-1520-264-23

 Change 1 2-38.5

(d) Rotate the positioner away from the upper OD EDM notch, and 

note the position along the time base line of the signal received 

from the thread run- out groove. This signal is located just outside

the gate on the right hand side of the CRT. Moisten a finger with 

couplant and damp this signal to gain familiarity. The 

appearance and amplitude of this signal is dependent upon the 

radius of the thread run-out groove. A large signal will be generated

from a sharper edge, as a lesser or nonexistent signal would be 

indicative of a smoother transition area. Reference Figure 5.

Figure 5. Signal from thread run-out groove

(e) Again rotate the POSITIONER 360 degrees to confirm the 

electronic gate positioning and verify the upper and lower OD 

EDM notches break the gate threshold. Reference Figure 6 for CRT

displays of upper and lower outside diameter EDM notches.

Figure 6a. Upper OD EDM notch Figure 6b. Lower OD EDM notch

(f) Perform the OD inspection scan after completion of the OD calibration.

Make two complete revolutions with the transducer in the OD position.

(g) Upon completion of the OD scan, wipe the calibration standard clean,

reapply couplant, and place the positioner on the calibration standard.

(h) Place the transducer in the ID guide hole. Rotate the POSITIONER, and

identify the signal obtained from the upper ID EDM notch.

Gate

Thread run-out

Gate

Upper OD

notch

Lower OD

notch
TM 1-1520-264-23

2-38.6 Change 1

 (i) Continue the rotation of the POSITIONER to locate the lower ID EDM 

 notch. Adjust the gain to achieve a signal height of 60% FSH. Rotate the 

 transducer carefully to minimize base line noise if necessary. Tighten the 

 set screw.

 (j) Rotate the POSITIONER 360 degrees to verify both upper and lower ID signals 

 are readily identifiable and break the gate threshold. Reference Figure 7 for 

 upper and lower ID EDM notch displays. 

 

Figure 7a. Upper ID notch Figure 7b. Lower ID notch

(3)INSPECTION PROCEDURE

(a) Perform the OD inspection scan after completion of the OD

calibration. Make two complete revolutions with the transducer in

the OD position.

(b) Perform the ID inspection scan after completion of the ID calibration

procedure. Make two complete revolutions with the transducer in the

ID position.

(c) Perform the calibration set up every time prior to inspecting the ID or

OD of a new bolt.

NOTE

The thin couplant layer is only adequate for approximately two passes

without signal amplitude loss. Excessive couplant under the positioner can

also create noise and erroneous signals on the CRT. When in doubt clean

the bolt, reapply couplant, and rescan.

(4) ACCEPTANCE/REJECTION CRITERIA

Relevant signals exceeding the 40% gate threshold are rejectable. ID

or OD cracks can appear anywhere within the gated area. Cracks may

be detected on both the ID and OD surfaces with either scan. The

signal received from a small crack will usually have a very quick rise

and fall time when scanning. A legitimate crack indication will have a

consistent location on the bolt perimeter and can be easily repeated on

subsequent rescans. Verify all indications by cleaning the bolt,

reapplying couplant and rescanning.

(5) POST CLEAN

Clean the bolt with a cloth dampened with water to remove couplant

residue.

Lower ID

notch

Upper ID

notch
 TM 1-1520-264-23

 Change 1 2-38.7/2-38.8 blank)

“S” SCAN

SUPPLEMENTAL SCAN FOR THE STRAP PACK BOLT INSPECTION

Description. An additional scan is required to detect cracks initiating at more severe

angles from the inner wall of the strap pack bolt.

(1) SET UP

(a) Apply couplant to the calibration standard, and smooth the couplant with your

finger to produce a uniform thin layer.

(b) Place the POSITIONER on the calibration standard, and insert the

TRANSDUCER in the “S” guide hole until it bottoms. Align the transducer

with the lower OD EDM notch.

(c) Identify the signal received from the notch, and adjust the gain to obtain 100%

FSH. Reference Figure 1 for a CRT display of the calibration notch.

Figure 1. “S” scan calibration notch signals

(2) INSPECTION PROCEDURE

(a) Do to the increased angle of inspection additional signals are received within

the gate. Reference Figure 1 to assist with signal interpretation. Damp

signals on the calibration standard with a finger moistened with couplant to

gain familiarity.

(b) This inspection technique focuses the sound beam on the ID mid-shank of the

bolt but will detect ID and OD cracks at other locations.

(a) Place the positioner on the bolt to be inspected, slowly rotate the

positioner making two passes with the “S” scan.

 (3) ACCEPTANCE/REJECTION CRITERIA

ID or OD cracks can appear anywhere within the gated area. The signal received

from a small crack will usually have a very quick rise and fall time when scanning.

Any relevant signal exceeding the gate threshhold is rejectable.

Lower OD

signal

Shoulder

signal
TM 1-1520-264-23

Figure 2-16. Main Rotor Pitch Housing

2-39
TM 1-1520-264-23

2.17 MAIN ROTOR FEATHERING BEARING HOUSING (ET).

2.17.1 Description (Figure 2-1 Index No. 17). The main rotor feathering bearing housing is between the main rotor

hub and the pitch housing. The feathering bearing allows the pitch housing assembly to move up and down.

2.17.2 Defects. This inspection is used to verify crack indications found visually on the main rotor feathering bearing

housing. No cracks are allowed.

2.17.3 Primary Method. Eddy Current.

2.17.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.17.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main rotor feathering bearing housing shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

2.17.3.3 Access. Not applicable.

2.17.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.17.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

2-40
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

2.17.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-17.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.17.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 2.17.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

2.17.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.17.4 Backup Method. None required.

2.17.5 System Securing. The main rotor feathering bearing housing, if removed, requires installation in accordance with

the applicable technical manuals listed in Table 1-1.

2.18 MAIN ROTOR STRIKER PLATE AND SHIMS (MT).

2.18.1 Description (Figure 2-1. Index No. 18). The main rotor striker plate and shims attach to the feathering bearing

housing providing a contact point for the main rotor droop stop follower.

2.18.2 Defects This inspection is used to verify crack indications found visually on the main rotor striker plate and shims.

No cracks are allowed.

2.18.3 Primary Method. Magnetic Particle.

2.18.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

2-41
TM 1-1520-264-23

Figure 2-17. Main Rotor Feathering Bearing Housing

2-42
TM 1-1520-264-23

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

2.18.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed striker plate using applicable positions of this procedure. If required, the main rotor striker plate and shims

shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

2.18.3.3 Access. Not applicable.

2.18.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.18.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

2.18.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 2-18.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five

seconds.

d. Inspect for cracks using the black light.

2.18.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.18.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

2.18.4 Backup Method. None required.

2.18.5 System Securing. Clean the main rotor striker plate and shims thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor

striker plate and shims, if removed, require installation in accordance with the applicable technical manuals listed in

Table 1-1.

2-43
TM 1-1520-264-23

Figure 2-18. Main Rotor Striker Plate and Shims

2-44
TM 1-1520-264-23

2.19 MAIN ROTOR HUB BEARING (ET).

2.19.1 Description (Figure 2-1. Index No. 2-19). The main rotor hub bearing provides a hinge point for the lead lag

link.

2.19.2 Defects. This inspection is used to verify crack indications found visually on the main rotor hub bearing. No

cracks are allowed.

2.19.3 Primary Method. Eddy Current.

2.19.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.19.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main rotor hub bearing shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

2.19.3.3 Access. Not applicable.

2.19.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.19.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

2-45
TM 1-1520-264-23

2.19.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-19.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.19.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 2.19.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

2.19.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.19.4 Backup Method. None required.

2.19.5 System Securing. The main rotor hub bearing, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

2.20 MAIN ROTOR LOWER SHOE (ET).

2.20.1 Description (Figure 2-1. Index No. 20). The main rotor lower shoe is attached at the base of the main rotor hub

and provides a mounting point for the droop stop follower.

2.20.2 Defects. This inspection is used to verify crack indications found visually on the main rotor lower shoe. No cracks

are allowed.

2.20.3 Primary Method. Eddy Current.

2.20.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.20.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main rotor lower shoe shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

2-46
TM 1-1520-264-23

Figure 2-19. Main Rotor Hub Bearing

2-47
TM 1-1520-264-23

2.20.3.3 Access. Not applicable.

2.20.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.20.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

2.20.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-20.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.20.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 2.20.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

2.20.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.20.4 Backup Method. None required.

2.20.5 System Securing. The main rotor lower shoe, if removed, requires installation in accordance

with the applicable technical manuals listed in Table 1-1.

2-48
TM 1-1520-264-23

Figure 2-20. Main Rotor Lower Shoe

2.21 MAIN ROTOR HEAD HUB LOAD PLATE (MT).

2.21.1 Description (Figure 2-1. Index No. 21). The main rotor head hub load plate provides a mounting surface for the

main rotor hub.

2.21.2 Defects. This inspection is used to verify crack indications found visually on the main rotor head hub load plate.

No cracks are allowed.

2.21.3 Primary Method. Magnetic Particle.

2.21.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

2.21.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main rotor

head hub load plate shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

2-49
TM 1-1520-264-23

2.21.3.3 Access. Not applicable.

2.21.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.21.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

2.21.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 2-21.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five 

seconds.

d. Inspect for cracks using the black light.

2.21.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.21.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

Figure 2-21. Main Rotor Head Hub Load Plate

2-50
TM 1-1520-264-23

2.21.4 Backup Method. None required.

2.21.5 System Securing. Clean the main rotor head hub load plate thoroughly to remove all residual magnetic particle

media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor head hub

load plate requires installation in accordance with the applicable technical manuals listed in Table 1-1.

2.22 MAIN ROTOR HUB BRACKETS (MT).

2.22.1 Description (Figure 2-1. Index No. 22). The main rotor hub brackets are attached at the inboard section of the

hub which provides support for the feathering bearing studs.

2.22.2 Defects. This inspection is used to verify crack indications found visually on the main rotor hub brackets. No

cracks are allowed.

2.22.3 Primary Method. Magnetic Particle.

2.22.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black.Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

2.22.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main rotor

hub bracket shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

2.22.3.3 Access. Not applicable.

2.22.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.22.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

2.22.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 2-22.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five 

seconds.

d. Inspect for cracks using the black light.

2-51
TM 1-1520-264-23

Figure 2-22. Main Rotor Hub Brackets

2.22.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.22.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

2.22.4 Backup Method. None required.

2.22.5 System Securing. Clean the main rotor hub brackets thoroughly to remove all residual magnetic particle media.

Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor hub brackets require

installation in accordance with the applicable technical manuals listed in Table 1-1.

2.23 MAIN ROTOR HUB LOWER PLATE (MT).

2.23.1 Description (Figure 2-1. Index No. 23). The main rotor hub lower plate provides the attachment point for the main

rotor strap packs.

2.23.2 Defects. This inspection is used to verify crack indications found visually on the main rotor hub lower plate. No

cracks are allowed.

2.23.3 Primary Method. Magnetic Particle.

2.23.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

2-52
TM 1-1520-264-23

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

2.23.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main rotor

hub lower plate shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

2.23.3.3 Access. Not applicable.

2.23.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.23.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

2.23.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 2-23.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five

seconds.

d. Inspect for cracks using the black light.

2.23.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.23.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

Figure 2-23. Main Rotor Hub Lower Plate

2-53
TM 1-1520-264-23

2.23.4 Backup Method. None required.

2.23.5 System Securing. Clean the main rotor hub lower plate thoroughly to remove all residual magnetic particle

media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor hub lower

plate requires installation in accordance with the applicable technical manuals listed in Table 1-1.

2.24 TAIL ROTOR FORK ASSEMBLY (HEAD AND TEETER STOP) (ET).

2.24.1 Description (Figure 2-1. Index No. 24). The tail rotor fork (head and teeter stop) assembly is a two-armed,

teetering assembly that provides attachment points for the four tail rotor blade assemblies.

2.24.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor fork assembly (head

and teeter stop). No cracks are allowed.

2.24.3 Primary Method. Eddy Current.

2.24.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz,90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.24.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail rotor fork assembly (head and teeter stop) shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

2.24.3.3 Access. Not applicable.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands and restraint equipment when

working above 10 feet on helicopter in a nontactical environment. Otherwise, personnel injury could result from

accidental falls.

2.24.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2-54
TM 1-1520-264-23

2.24.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 30°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch riotch in test block. (See the standard instrument display shown in Figure 1-7.)

2.24.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-24.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.24.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 2.24.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

2.24.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.24.4 Backup Method. None required.

2.24.5 System Securing. The tail rotor fork assembly (head and teeter stop), if removed, requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

2-55
TM 1-1520-264-23

Figure 2-24. Tail Rotor Fork Assembly (Head and Teeter Stop)

2-56
TM 1-1520-264-23

2.25 TAIL ROTOR BLADE (PT).

2.25.1 Description (Figure 2-1. Index No. 25). The tail rotor blade assemblies are rotating airfoils. The blade is

constructed with a stainless steel leading edge. Eleven aluminum honeycomb stiffeners are bonded into the spar, and

the blade skin is aluminum with bonded doublers near the root fitting.

2.25.2 Defects. Defects can occur anywhere on the surface of the tail rotor blade. No cracks are allowed.

2.25.3 Primary Method. Fluorescent Penetrant.

2.25.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-1-

25135 level 3 penetrant materials shall be selected from the approved list in Table 1-8.

2.25.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail rotor blade shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

2.25.3.3 Access. Not applicable.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured

stands and restraint equipment when working above 10 feet on helicopter in a

nontactical environment. Otherwise, personnel injury could result from accidental

falls.

2.25.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

2.25.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,

paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 2-25.

Figure 2-25. Tail Rotor Blade

2-57
TM 1-1520-264-23

2.25.3.6 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.25.4 Backup Method. None required.

2.25.5 System Securing. Clean the tail rotor blade to remove inspection media. Refer to Post Cleaning and

Restoration of Part or Area After NDI, paragraph 1.4.16. The tail rotor blade, if removed, requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

2.26 TAIL ROTOR BLADE (VOIDS) (BT).

2.26.1 Description (Figure 2-1. Index No. 26). The tail rotor blade assemblies are rotating airfoils. The blade is

constructed with a stainless steel leading edge. Eleven aluminum honeycomb stiffeners are bonded into the spar, and

the blade skin is aluminum with bonded doublers near the root fitting.

2.26.2 Defects. Void damage may occur anywhere on both sides of the blade.

NOTE

A void is defined as an unbonded area that is supposed to be bonded. Many

subdefinitions are given, such as lack of adhesive, gas pocket, misfit, etc.

However, this manual makes no distinction among these, instead grouping them

all under one general term ("void").

2.26.3 Primary Method. Bond Testing.

2.26.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Bond Test Unit

b. Probe, Mechanical Impedance Analysis

c. Probe Holder

d. Cable Assembly

e. Test Block, metal honeycomb with skin thickness closest to that of the panel to be inspected

f. Test Block, Composite Defect Standard #1

g. Test Block, Composite Defect Standard #3

h. Teflon Tape, refer to Table 1-8

i. Aircraft Marking Pencil, refer to Table 1-8

2.26.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. Partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using applicable positions of this procedure. If required, remove the tail rotor blades in accordance with

the applicable technical manuals listed in Table 1-1.

2-58
TM 1-1520-264-23

2.26.3.3 Access. Not applicable.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured

stands and restraint equipment when working above 10 feet on helicopter in a

nontactical environment. Otherwise, personnel injury could result from accidental

falls.

2.26.3.4 Preparation of Part. The components shall be thoroughly cleaned. Refer to Preparation of Part or Area for

NDI, paragraph 1.4.4.

2.26.3.5 NDI Equipment Settings. Refer to Bond Test Equipment, paragraph 1.4.6.1.

a. Attach cable and probe to Bondmaster. Protect probe with Teflon tape and install in probe holder.

b. Turn on Bondmaster, press SPCL, and make the following adjustments:

H Pos -40%

VPos - 80%

PHASE REF - 0

DRIVE - MID

c. Press SET and select DISPLAY - PHASE.

d. Place probe on the good area of test blocks and press GOOD PART. Do this several times while moving the

probe to different spots in the good area of the standard. Note the video signature for each. Select and enter

a representative good area by pressing GOOD PART one last time.

e. Place probe on void area of test block and press BAD PART. Do this several times while moving the probe

slightly to different positions within the void area. Select and enter a position that gives a strong difference

between good and void areas. Use DIFF soft key to observe difference between good and bad areas of test

block.

NOTE

If, during setup, the flying spot deflects upward or to the side when the probe

passes over the bad part instead of the desired down deflection toward the alarm

box, press SPCL and toggle to a different phase setting (90, 180, or 270), and

repeat steps d. and e. Continue to try phase setting until the flying spot moves in

the desired down direction.

f. Place probe on good area of test block and press RUN. Flying spot should be near the top-center of the

ACTIVE screen. If not, press NULL. Slide probe from good to void area and note response from flying spot.

This response should provide both amplitude (vertical) and phase (horizontal) movement. The default

gate/alarm setting may be incorrect for this setup. Turn off or reset gate/alarm as desired.

g. The Bondmaster is programmed to automatically set test parameters to a start-up or initial bond test. By

following the steps outlined above, adjustments to the FREQ, GAIN, and ALARM can help to refine the

selectivity in locating defects among differing composite materials.

2-59
TM 1-1520-264-23

2.26.3.6 Inspection Procedure. Refer to Bond Test Method, paragraph 1.4.6 and inspection areas are shown in Figure

2-26.

a. Skin-to-Honeycomb Voids. Place probe on tail rotor blade in location where test for skin-to-honeycomb bond

separation is desired and press NULL. Move probe from good to suspect area and note response. A strong

amplitude change and phase shift similar to the standard is indicative of a void. This set-up is very sensitive

to thin skin-to-core bonding. Move probe slowly over the skin and note the slight amplitude change (bounce)

as the probe senses alternately the honeycomb cell nodes and cell walls.

NOTE

The basic setup provided above also selects a frequency that provide a

satisfactory inspection for voids associated with skin-to-spar, skin-to-trailing

edge, doubler-to-doubler and doubler-to-skin, and trim tab bonding.

b. Use the NULL and GAIN adjustments to reset the ACTIVE screen for the areas to be inspected (do not go

back to SET mode). Also, compare similar areas. For example, to check for spar to skin voids, check front

and back of blade in the same area, or check another blade in the same area. Observe that, when moving

the probe chordwise from the spar to the trailing edge, the transitions at the spar-to-honeycomb and the

honeycomb-to-trailing edge strip are easily detected. When inspecting these areas, adjust the NULL and

GAIN and move the probe carefully along the transition using a straight edge or other guide. A localized

phase and amplitude shift similar to the test block indicates a void.

Figure 2-26. Tail Rotor Blade (Voids)

2-60
TM 1-1520-264-23

2.26.3.7 Marking and Recording of Inspection Results. Mark and record as required by paragraph 1.3.

NOTE

Attention shall be directed to accurately mark the boundaries of all voids. These

markings will be needed to determine acceptance or rejection criteria in

accordance with applicable technical manuals.

2.26.4 Backup Method. None required.

2.26.5 System Securing. The tail rotor blades, if removed, require installation in accordance with the applicable

technical manual listed in Table 1-1.

2.27 TAIL ROTOR BLADES (FLUID) (RT).

2.27.1 Description (Figure 2-1. Index No. 27). The tail rotor blade assemblies are rotating airfoils. The blade is

constructed with a stainless steel leading edge. Eleven aluminum honeycomb stiffeners are bonded into the spar, and

the blade skin is aluminum with bonded doublers near the root fitting.

2.27.2 Defects. Fluid in the honeycomb core.

2.27.3 Primary Method. Radiography.

Radiation Hazard

Assure compliance with all applicable safety precautions set forth in TM 55-1500-

335-23 (Nondestructive Inspection Methods manual) listed in Table 1.1. A hazard

associated with exposure to ionizing radiation is that serious injury can be inflicted

without pain, burning or other sense of discomfort during the exposure period.

Radiation protection shall be utilized in accordance with AR40-14/DLAR 1000.28.

2.27.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. X-ray Unit

b. Tripod, X-ray tubehead stand

c. Film Processor

d. Film, Ready Pack 14 inch x 17 inch

e. Marking Material, refer to Table 1-8

2.27.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. Partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail rotor blades shall be removed in accordance with applicable

technical manuals listed in Table 1-1.

2-61
TM 1-1520-264-23

2.27.3.3 Access. Not applicable.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured

stands and restraint equipment when working above 10 feet on helicopter in a

nontactical environment. Otherwise, personnel injury could result from accidental

falls.

2.27.3.4 Preparation of Part. The rotor blade shall be thoroughly cleaned. Refer to Preparation of Part or Area for

NDI, paragraph 1.4.4.

2.27.3.5 NDI Equipment Settings.

a. Refer to Radiographic (X-ray) method, paragraph 1.4.10.

b. Typical equipment settings, inspection, and exposure data are given in Figure 2-27.

2.27.3.6 Inspection Procedure. Inspect designated areas, refer to Figure 2-27 for typical fluid entrapment and

source/film placement.

a. Position film and desired nameplate data for exposure number 1.

b. Position X-ray tubehead for exposure number 1.

c. Set X-ray unit to the values given in the Radiographic Inspection Data chart for exposure number 1.

d. Make exposure number 1.

e. Remove exposed film.

f. Repeat inspection procedure (steps a. through e. above) for each exposure.

g. Process and interpret film for defects as noted in paragraph 2.27.2 and as shown in Figure 2-27.

2.27.4 Backup Method. None required.

2.27.5 System Securing. The tail rotor blade shall be cleaned as necessary. Refer to Post Cleaning and Restoration

of Part or Area After NDI, paragraph 1.4.6.1. The tail rotor blade, if off the helicopter, requires reinstallation in

accordance with the applicable technical manual listed in Table 1-1.

2-62
TM 1-1520-264-23

Figure 2-27. Tail Rotor Blades (Fluid) (Sheet 1 of 2)

2-63
TM 1-1520-264-23

Figure 2-27. Tail Rotor Blades (Fluid) (Sheet 2 of 2)

2-64
TM 1-1520-264-23

2.28 TAIL ROTOR HUB (ET).

2.28.1 Description (Figure 2-1. Index No. 28). The tail rotor hub has a stainless steel strap pack that passes

through the hub to provide for attachment of the tail rotor blades.

2.28.2 Defects. Defects can occur anywhere on the surface of the tail rotor hub. No cracks are allowed.

2.28.3 Primary Method. Eddy Current.

2.28.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.28.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail rotor hub shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

2.28.3.3 Access. Not applicable.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured

stands and restraint equipment when working above 10 feet on helicopter in a

nontactical environment. Otherwise, personnel injury could result from accidental

falls.

2.28.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.28.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 30°

Probe drive - mid

2-65
TM 1-1520-264-23

LPF -100

HPF -0

H Pos - 80%

VPos -20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in

Figure 1-7.)

2.28.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-28.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.28.3.1 may be used depending primarily on

the ease of accessibility and user friendliness. If the probes are changed, steps

2.28.3.5 b. (1), (2), and (3) shall be repeated each time a change is made.

2.28.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.28.4 Backup Method. None required.

2.28.5 System Securing. The tail rotor hub, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

2.29 TAIL ROTOR CLAMPS AND LOCKING PLATES (ET).

2.29.1 Description (Figure 2-1. Index No. 29). The tail rotor clamps and locking plates provide for attachment of

the de-icing harness.

2.29.2 Defects. Defects can occur anywhere on the surface of the tail rotor clamps and locking plates. No cracks

are allowed.

2.29.3 Primary Method. Eddy Current.

2-66
TM 1-1520-264-23

Figure 2-28. Tail Rotor Hub

2-67
TM 1-1520-264-23

2.29.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

2.29.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail rotor clamps and locking plates shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

2.29.3.3 Access. Not applicable.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured

stands and restraint equipment when working above 10 feet on helicopter in a

nontactical environment. Otherwise, personnel injury could result from accidental

falls.

2.29.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

2.29.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos -20%

2-68
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in' test block. (See the standard instrument display shown in

Figure 1-7.)

2.29.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 2-29.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 2.29.3.1 may be used depending primarily on

the ease of accessibility and user friendliness. If the probes are changed, steps

2.29.3.5 b. (1), (2), and (3) shall be repeated each time a change is made.

2.29.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

2.29.4 Backup Method. None required.

2.29.5 System Securing. The tail rotor clamps and locking plates, if removed, require installation in accordance with

the applicable technical manuals listed in Table 1-1.

2-69
TM 1-1520-264-23

Figure 2-29. Tail Rotor Clamps and Locking Plates

2-70
 TM 1-1520-264-23

 Change 1 2-71

2.30 Mast Mounted Assembly (BT)

2.30.1 Description. The base-plate is mounted to the top of the mast.

2.30.2 Defect. Voids may occur on the bottom surface extending from the mast to

outboard 13 inches.

NOTE

A void is defined as a unbonded area that is supposed to be bonded .

Many subdefinitions of voids are given such as lack of adhesive, gas

pocket, misfit , etc. However, this manual makes no distinction among

these; grouping them all under one general term, “void”.

2.30.3 Primary Method. Bond Testing.

2.30.3.1 NDI Equipment and Materials. (refer to Appendix B.)

 a. Bond Test Unit

 b. Probe, Mechanical Impedance Analysis

 c. Probe Holder

 d. Cable Assembly

 e. Test Block, composite skin and Nomex honeycomb,

P/N 76091902-001/002

 f. Aircraft Marking Pencil, refer to Table 1-8

2.30.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground

 maintenance in accordance with applicable technical manuals listed in Table

 1-1. Inspection areas are accessible with the radome installed on the

 helicopter.

2.30.3.3 Access. Both radio frequency interferometers (RFI) antenna assembly

 and receiver assembly and the attaching cannon plugs must be removed

 to provide complete access.
TM 1-1520-264-23

2-72 Change 1

WARNING

Maintenance Platforms/workstands

Use only appropriate platforms, workstands, or other approved locally

Procured stands and restrain equipment when working above 10 feet on

helicopters in a nontactical environment. Otherwise, personal injury could

result from accidental falls.

2.30.3.4 Preparation of Part. The bottom side of the base-plate shall be thoroughly

 cleaned. Refer to Preparation of Part Area for NDI, paragraph 1.4.4 Do

 not remove paint.

2-30.3.5 NDI Equipment Settings. Refer to Bond Test Equipment, paragraph

 1.4.6.1

 a. Attach cable and probe to the Bondmaster. Install the probe in the

probe holder.

 b. Turn on the Bondmaster, press SPCL, and make the following

adjustments:

H Pos 77%

V Pos 100%

PHASE RED 270 degrees

DRIVE HIGH

 c. Press SPCL a second time and make the following adjustments:

V-GAIN 26.0db

T-Erase 1

NOTE

V-GAIN may be adjusted to plus or minus 3db to fine tune the

instrument as the probe especially as it moved outboard during

the inspection.

 d. Press SET and select DISPLAY AMPL1

 e. Adjust the frequency to 5.01 kHz.

 f. Press the RUN key and reset the V-GAIN to 26.0dB.

 g. Place the probe on a good area of the test block and press NULL.

 The dot should be at the top of the screen, near the center.
 TM 1-1520-264-23

 Change 1 2-73/(2-74 blank)

 h. Slide the probe to the inboard 1⁄2 inch void and note the dot position.

The dot should fall to the bottom center of the screen well within the

alarm box causing the alarm to activate with a steady tone.

 i. Press the ALARM key and select HORN VOL. The alarm sound

 volume may be adjusted to operator preference.

 j. Press the RUN key and place the probe on the good area near the

 inboard void.

 k. Press the NULL key. The dot should move to the top center of the

 screen. As the probe is moved outboard of the mast, note the

 average position of the dot. It may be necessary to re-null to allow

 for the progressively thinner skin towards the outboard areas.

 l. Although the Bondmaster is programmed to automatically set test

 parameters, the specific requirements of this inspection require that

 the preceeding be used as a starting point.

2.30.3.6 Inspection Procedure. Refer to Bond Test method, paragraph 1.4.6.

 a. Using the aircraft marking pencil, trace out a pattern of concentric

 circles beginning 1⁄2 in ch from the mast and spaced 1⁄2 inch apart so

 that the last circle is 12 1⁄2 to 13 inches from the mast. Make the

 marks only dark enough to be visible at close distance. If an attach-

 ment or other feature intersects the circle, merely stop and restart on

 the other side of the obstruction.

 b. Place the probe on the underside of the base-plate as close to the

 mast as possible.

 c. Scan around the mast. Actual inspection can be carried out by doing

 one half the base-plate at a time. Move the center of the probe out to

 each progressively larger concentric circle. Use the circle as a guide

 to insure complete coverage by keeping the probe centered on the

 circle.

 d. Mark all areas that cause the alarm to sound with a steady tone.
TM 1-1520-264-23

SECTION III

DRIVE SYSTEM

3. GENERAL.

3.1 CONTENTS. The drive system inspection items covered in this section are those items of the AH-64A

helicopter transmission, gear boxes, drive shafts and components listed in the Drive System Inspection Index (Table

3-1). Corresponding inspection figures and the applicable text paragraphs are listed opposite each inspection item. The

index number for each item may be used to locate it in Figure 3-1.

Table 3-1. Drive System Inspection Index

Index

Number

Nomenclature Inspection

Method

Paragraph

Number

Figure

Number

*2 Drive Shafts ET 3.2 3-2

*3 Drivetrain Couplings ET 3.3 3-3

4 Drivetrain Flanges MT 3.4 3-4

5 Damper and Anti-Flail Supports ET 3.5 3-5

6 Forward Hanger Bearing Flange MT 3.6 3-6

7 Forward Hanger Bearing Support ET 3.7 3-7

8 Aft Hanger Bearing Flange MT 3.8 3-8

9 Aft Hanger Bearing Support ET 3.9 3-9

10 Intermediate Gearbox Centrifugal Fan ET 3.10 3-10

*11 Engine Nose Gearbox ET 3.11 3-11

12 Engine Nose Gearbox Input Quill Shaft MT 3.12 3-12

*13 Main Transmission ET 3.13 3-13

14 Main Transmission Compressor Drive Adapter ET 3.14 3-14

15 Main Transmission APU Drive Flange MT 3.15 3-15

16 Main Transmission Tail Rotor Drive Flange MT 3.16 3-16

17 Main Rotor Gearshaft Drive Gear Teeth MT 3.17 3-17

*18 Main Rotor Mast Support Base ET 3.18 3-18

*19 Intermediate Gearbox ET 3.19 3-19

20 Intermediate Gearbox Retainers ET 3.20 3-20

21 Intermediate Gearbox Flange and Shouldered Shaft MT 3.21 3-21

*22 Tail Rotor Gearbox ET 3.22 3-22

3-1
TM 1-1520-264-23

Table 3-1. Drive System Inspection Index - Continued

Index

Number

Nomenclature Inspection

Method

Paragraph

Number

Figure

Number

23 Tail Rotor Gearbox Shouldered Shaft MT 3.23 3-23

24 Tail Rotor Gearbox Retainers ET 3.24 3-24

*25 Tail Rotor Gearbox Forward and Aft Strut MT 3.25 3-25

26 Tail Rotor Gearbox Forward and Aft Strut Fittings MT 3.26 3-26

*27 Main Rotor Head (Hub) ET 3.27

*28 Main Rotor Support Mast MT 3.28

NOTE: *Indicates Flight Safety Part.

Figure 3-1. Drive System (Sheet 1 of 2)

3-2
TM 1-1520-264-23

Figure 3-1. Drive System (Sheet 2 of 2)

3-3
TM 1-1520-264-23

3.2 DRIVE SHAFTS (ET).

3.2.1 Description (Figure 3-1. Index No. 2). The drive shaft assembly links the helicopter drive system gearboxes

to the main transmission. The system consists of input drive shafts 1 and 2; tail rotor drive shafts 3, 4, 5, and 6; and a

titanium APU drive shaft 7. See Figure 3-2 for drive shaft locations.

3.2.2 Defects. This inspection is used to verify crack indications found visually on the drive shafts. No cracks are

allowed.

3.2.3 Primary Method. Eddy Current.

3.2.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches) (use for 1 through 6)

f. Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches) (use for drive shaft 7)

g. Teflon Tape, refer to Table 1-8

h. Aircraft Marking Pencil, refer to Table 1-8

Exercise extreme caution when handling and inspecting the drive shaft

assemblies. The assembly may be rendered unserviceable by even slight dents

or scratches.

3.2.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the drive shaft shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

3.2.3.3 Access. Accessibility of the drive shafts varies considerably. Refer to Figure 1-4 and Table 1-2 to locate

applicable access provisions.

3.2.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3-4
TM 1-1520-264-23

Figure 3-2. Drive Shafts

3-5
TM 1-1520-264-23

3.2.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - (56° aluminum) (30° titanium)

Probe drive - mid

LPF - 100

HPF -O

H Pos - 80%

VPos -20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3.2.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-2.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.2.3.1 may be used depending primarily on

the ease of accessibility and user friendliness. If the probes are changed, steps

3.2.3.5 b. (1), (2), and (3) shall be repeated each time a change is made.

3.2.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.2.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

3.2.5 System Securing. The drive shafts, if removed, require installation in accordance with the applicable

technical manuals listed in Table 1-1.

3-6
TM 1-1520-264-23

3.3 DRIVETRAIN COUPLINGS (ET).

3.3.1 Description (Figure 3-1. Index No. 3). The drivetrain couplings are attached to each end of the drive shaft to

provide flexibility of the drive shafts during operation.

3.3.2 Defects. This inspection is used to verify crack indications found visually on the drivetrain couplings. No

cracks are allowed.

3.3.3 Primary Method. Eddy Current.

3.3.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

3.3.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the drivetrain couplings shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

3.3.3.3 Access. Accessibility of the drivetrain couplings varies considerably. Refer to Figure 1 -4 and Table 1-2 to

locate applicable access provisions.

3.3.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.3.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 30°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3-7
TM 1-1520-264-23

3.3.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-3.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.3.3.1 may be used depending primarily on

the ease of accessibility and user friendliness. If the probes are changed, steps

3.3.3.5 b. (1), (2), and (3) shall be repeated each time a change is made.

3.3.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.3.4 Backup Method. None required.

3.3.5 System Securing. The drivetrain couplings, if removed, require installation in accordance with the applicable

technical manuals listed in Table 1-1.

3.4 DRIVETRAIN FLANGES (MT).

3.4.1 Description (Figure 3-1. Index No. 4). The drivetrain flanges are used throughout the drive system to mate

the drive shaft assemblies to the main transmission and various gear boxes contained in the drive system.

3.4.2 Defects. This inspection is used to verify crack indications found visually on the drivetrain flanges. No cracks

are allowed.

3.4.3 Primary Method. Magnetic Particle.

3.4.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

3.4.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the drive shaft

removed in accordance with the applicable technical manuals listed in Table 1-1.

3-8
TM 1-1520-264-23

Figure 3-3. Drivetrain Couplings

3-9
TM 1-1520-264-23

3.4.3.3 Access. Accessibility of drivetrain flanges varies considerably. Refer to Figure 1-4 and Table 1-2 to locate

applicable access provisions.

3.4.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.4.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.4.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The position required for this inspection is illustrated in Figure 3-4.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

3.4.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.4.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

Figure 3-4. Drivetrain Flanges

3-10
TM 1-1520-264-23

3.4.4 Backup Method. None required.

3.4.5 System Securing. Clean the drivetrain flange thoroughly to remove all residual magnetic particle media.

Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The drive shaft requires installation

in accordance with the applicable technical manuals listed in Table 1-1.

3.5 DAMPER AND ANTI-FLAIL SUPPORTS (ET).

3.5.1 Description (Figure 3-1. Index No. 5). The damper and anti-flail supports are installed on the drive shafts

between the main transmission and the intermediate gearbox. The damper assemblies define the natural frequencies of

the drive shafts to allow them to operate at critical speeds and the anti-flail assemblies hold the drive shafts in position if

partial or full separation of the drive shaft occurs.

3.5.2 Defects. This inspection is used to verify crack indications found visually on the damper and anti-flail

supports. No cracks are allowed.

3.5.3 Primary Method. Eddy Current.

3.5.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

3.5.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the damper and anti-flail supports shall be removed in accordance

with the applicable technical manuals listed in Table 1-1.

3.5.3.3 Access. Accessibility of the damper and anti-flail supports varies considerably. Refer to Figure 1-4 and Table

1-2 to locate applicable access provisions.

3.5.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3-11
TM 1-1520-264-23

3.5.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3.5.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-5.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.5.3.1 may be used depending primarily on

the ease of accessibility and user friendliness. If the probes are changed, steps

3.5.3.5 b. (1), (2), and (3) shall be repeated each time a change is made.

3.5.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.5.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

3.5.5 System Securing. The damper and anti-flail supports, if removed, require installation in accordance with the

applicable technical manuals listed in Table 1-1.

3-12
TM 1-1520-264-23

Figure 3-5. Damper and Anti-Flail Supports

3.6 FORWARD HANGER BEARING FLANGE (MT).

3.6.1 Description (Figure 3-1. Index No. 6). The forward hanger bearing flange connects drive shafts 3 and 4.

The forward hanger bearing assembly support and align drive shafts 3 and 4.

3.6.2 Defects. This inspection is used to verify crack indications found visually on the forward hanger bearing

flange. No cracks are allowed.

3.6.3 Primary Method. Magnetic Particle.

3.6.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

3-13
TM 1-1520-264-23

3.6.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the drive shaft

removed in accordance with the applicable technical manuals listed in Table 1 -1.

3.6.3.3 Access. Access is through the deck area doors, fairing, and walkway area (Figure 1-4, Items T250, T290, and

T325).

3.6.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.6.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.6.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The position required for this inspection is illustrated in Figure 3-6.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

3.6.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

Figure 3-6. Forward Hanger Bearing Flange

3-14
TM 1-1520-264-23

3.6.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

3.6.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

3.6.5 System Securing. Clean the forward hanger bearing flange thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The forward hanger

bearing flange requires installation in accordance with the applicable technical manuals listed in Table 1-1.

3.7 FORWARD HANGER BEARING SUPPORT (E).

3.7.1 Description (Figure 3-1. Index No. 7). The forward hanger bearing support is an "A" Frame which supports

the sealed bearing.

3.7.2 Defects. This inspection is used to verify crack indications found visually on the forward hanger bearing

support. No cracks are allowed.

3.7.3 Primary Method. Eddy Current.

3.7.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

3.7.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the forward hanger bearing support shall be removed in accordance

with the applicable technical manuals listed in Table 1-1.

3.7.3.3 Access. Access is through the deck area doors and fairing (see Figure 1-4, Items T250, T290, and T325).

3.7.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3-15
TM 1-1520-264-23

3.7.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”

Frequency Fl - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3.7.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-7.

Figure 3-7. Forward Hanger Bearing Support

3-16
TM 1-1520-264-23

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.7.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 3.7.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

3.7.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.7.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

3.7.5 System Securing. The forward hanger bearing support, if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

3.8 AFT HANGER BEARING FLANGE (MT).

3.8.1 Description (Figure 3-1. Index No. 8). The aft hanger bearing flange connects drive shaft 4 and 5. The aft

hanger bearing assembly supports and aligns drive shafts 4 and 5.

3.8.2 Defects. This inspection is used to verify crack indications found visually on the aft hanger bearing flange. No

cracks are allowed.

3.8.3 Primary Method. Magnetic Particle.

3.8.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

3.8.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using applicable positions of this procedure. If required, the drive shaft shall be removed in accordance

with the applicable technical manuals listed in Table 1-1.

3.8.3.3 Access. Access is through the tail rotor drive shaft fairing (Figure 1-4, Item R410).

3.8.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3-17
TM 1-1520-264-23

3.8.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.8.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The position required for this inspection is illustrated in Figure 3-8.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

3.8.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.8.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

3.8.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

3.8.5 System Securing. Clean the aft hanger bearing flange thoroughly to remove all residual magnetic particle

media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16.The aft hanger bearing

flange, if removed, requires installation in accordance with the applicable technical manuals listed in Table 1-1.

3.9 AFT HANGER BEARING SUPPORT (ET).

3.9.1 Description (Figure 3-1. Index No. 9). The aft hanger bearing support is semi rigid consisting of a single

support and a sealed bearing assembly. The support incorporates three spherical bearings in the mount holes which

mount the support to the bracket.

3.9.2 Defects. This inspection is used to verify crack indications found visually on the aft hanger bearing support.

No cracks are allowed.

3.9.3 Primary Method. Eddy Current.

3.9.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current lnspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

3-18
TM 1-1520-264-23

Figure 3-8. Aft Hanger Bearing Flange

3-19
TM 1-1520-264-23

3.9.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be. performed on all exposed surfaces of

the installed part using this procedure. If required, the aft hanger bearing support shall be removed in accordance with

the applicable technical manuals listed in Table 1-1.

3.9.3.3 Access. Access is through the tail rotor drive shaft fairing (Figure 1-4, Item R410).

3.9.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.9.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”

.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3.9.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-9.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.9.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 3.9.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

3-20
TM 1-1520-264-23

Figure 3-9. Aft Hanger Bearing Support

3-21
TM 1-1520-264-23

3.9.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as

required by paragraph 1.3.

3.9.4 Backup Method. None required.

3.9.5 System Securing. The aft hanger bearing support, if removed, requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

3.10 INTERMEDIATE GEARBOX CENTRIFUGAL FAN (ET).

3.10.1 Description (Figure 3-1. Index No. 10). The intermediate gearbox centrifugal fan is mounted to the

intermediate gearbox input flange. The centrifugal-fan maintains the intermediate gearbox assembly at normal operating

temperature.

3.10.2 Defects. This inspection is used to verify crack indications found visually on the intermediate gearbox

centrifugal fan. No cracks are allowed.

3.10.3 Primary Method. Eddy Current.

3.10.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

3.10.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the intermediate gearbox centrifugal fan shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

3.10.3.3 Access. Not applicable.

3.10.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3-22
TM 1-1520-264-23

3.10.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3.10.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-10.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.10.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 3.10.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

3.10.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.10.4 Backup Method. None required.

3.10.5 System Securing. The intermediate gearbox centrifugal fan, if removed, requires installation in accordance

with the applicable technical manuals listed in Table 1-1.

3-23
TM 1-1520-264-23

NDI_AH64_F3_10

Figure 3-10. Intermediate Gearbox Centrifugal Fan

3-24
TM 1-1520-264-23

3.11 ENGINE NOSE GEARBOX (ET).

3.11 .1 Description (Figure 3-1. Index No. 11). The engine nose gearbox assembly is mounted on the forward end of

each engine nacelle. The engine nose gearbox assemblies change the drive angle and reduce the engine RPM output to

the main transmission.

3.11.2 Defects. This inspection is used to verify crack indications found visually on the engine nose gearbox. No

cracks are allowed.

3.11.3 Primary Method. Eddy Current.

3.11.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)

g. Teflon Tape, refer to Table 1-8

h. Aircraft Marking Pencil, refer to Table 1-8

3.1 1.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the engine nose gearbox shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

3.11.3.3 Access. Access is through the engine nose gearbox fairing (see Figure 1-4, Item LN6 and RN6).

3.11.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.11.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII

Frequency F1 - 200 KHz F2 -off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

3-25
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3.11.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-11.

NOTE

The engine nose gearbox contains a higher conductivity magnesium which will require the use of the

aluminum test block when performing inspections in these areas. Refer to paragraph 1.4.11.4, Sorting

Metal Using Eddy Current, to determine what test block is best suited for this inspection.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.11.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 3.1 1.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

3.11.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.11.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

3.11.5 System Securing. The engine nose gearbox, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

3.12 ENGINE NOSE GEARBOX INPUT QUILL SHAFT (MT).

3.12.1 Description (Figure 3-1. Index No. 12). The engine nose gearbox input quill shaft transmits power from the

engine to the nose gearbox.

3.12.2 Defects. This inspection is used to verify crack indications found visually on the engine nose gearbox input

quill shaft. No cracks are allowed.

3.12.3 Primary Method. Magnetic Particle.

3-26
TM 1-1520-264-23

Figure 3-11. Engine Nose Gearbox

3-27
TM 1-1520-264-23

3.12.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

3.12.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the engine nose

gearbox input quill shaft removed in accordance with the applicable technical manuals listed in Table 1-1.

3.12.3.3 Access. Not applicable.

3.12.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.12.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.12.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The position required for this inspection is illustrated in Figure 3-12.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more 

than five seconds.

d. Inspect for cracks using the black light.

Figure 3-12. Engine Nose Gearbox Input Quill Shaft

3-28
TM 1-1520-264-23

3.12.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.12.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

3.12.4 Backup Method. None required.

3.12.5 System Securing. Clean the engine nose gearbox input quill shaft thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The engine nose

gearbox input quill shaft requires installation in accordance with the applicable technical manuals listed in Table 1-1.

3.13 MAIN TRANSMISSION (ET).

3.13.1 Description (Figure 3-1. Index No. 13). The main transmission is the primary drive for the main rotor, tail

rotor, and accessories. The main transmission is located beneath the main rotor support mast base assembly.

3.13.2 Defects. This inspection is used to verify crack indications found visually on the main transmission. No cracks

are allowed.

3.13.3 Primary Method. Eddy Current.

3.13.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 1 00 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)

g. Teflon Tape, refer to Table 1-8

h. Aircraft Marking Pencil, refer to Table 1-8

3.13.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main transmission shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

3.13.3.3 Access. Access is through the main rotor transmission panel (see Figure 1-4, Items L200

and R200).

3.13.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3-29
TM 1-1520-264-23

3.13.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII

Frequency F1 - 200 KHz F2 -off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3.13.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-13.

NOTE

The main transmission contains a higher conductivity magnesium which will require the use of the

aluminum test block when performing inspections in these areas, refer to paragraph 1.4.11.4, Sorting

Metal Using Eddy Current, to determine what test block is best suited for this inspection.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.13.3.1 may be used depending primarily on the ease

of accessibility and user friendliness. If the probes are changed, steps 3.13.3.5 b. (1), (2),

and (3) shall be repeated each time a change is made.

3.13.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3-30
TM 1-1520-264-23

Figure 3-13. Main Transmission

3-31
TM 1-1520-264-23

3.13.4 Backup Method. None required.

3.13.5 System Securing. The main transmission, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

3.14 MAIN TRANSMISSION COMPRESSOR DRIVE ADAPTER (ET).

3.14.1 Description (Figure 3-1. Index No. 14). The main transmission compressor drive adapter provides for

attachment of the main transmission to the shaft drive compressor.

3.14.2 Defects. This inspection is used to verify crack indications found visually on the main transmission compressor

drive adapter. No cracks are allowed.

3.14.3 Primary Method. Eddy Current.

3.14.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

3.14.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main

transmission compressor drive adapter removed in accordance with the applicable technical manuals listed in Table 1-1.

3.14.3.3 Access. Not applicable.

3.14.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.14.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII

Frequency F1 - 200 KHz F2 -off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

3-32
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical 

signal when probe is passed over 0.040-inch notch in test block. (See the standard instrument 

display shown in Figure 1-7.)

3.14.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-14.

a. Place probe on a good area in the inspection location and null. Adjust phase as required

to obtain horizontal lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.14.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 3.14.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

3.14.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.14.4 Backup Method. None required.

3.14.5 System Securing. The main transmission compressor drive adapter requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

3.15 MAIN TRANSMISSION APU DRIVE FLANGE (MT).

3.15.1 Description (Figure 3-1. Index No. 15). The main transmission APU drive flange is externally splined which

provides for connection of the number 7 APU drive shaft and the main transmission.

3.15.2 Defects. This inspection is used to verify crack indications found visually on the main transmission APU drive

flange. No cracks are allowed.

3.15.3 Primary Method. Magnetic Particle.

3.15.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

3-33
TM 1-1520-264-23

Figure 3-14. Main Transmission Compressor Drive Adapter

3-34
TM 1-1520-264-23

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

3.15.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main

transmission APU drive flange removed in accordance with the applicable technical manuals listed in Table 1-1.

3.15.3.3 Access. Not applicable.

3.15.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.15.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.15.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the

orientation of possible cracks. Positions required for this inspection are illustrated in Figure 3-15.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for

no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 3.15.3.8.

f. Repeat steps a. through e. for position 2.

NDI AH-64_F3_15

Figure 3-15. Main Transmission APU Drive Flange

3-35
TM 1-1520-264-23

3.15.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.15.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

3.15.4 Backup Method. None required.

3.15.5 System Securing. Clean the main transmission APU drive flange thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main

transmission APU drive flange requires installation in accordance with the applicable technical manuals listed in Table

1-1.

3.16 MAIN TRANSMISSION TAIL ROTOR DRIVE FLANGE (MT).

3.16.1 Description (Figure 3-1. Index No. 16). The main transmission tail rotor drive flange is externally splined

which provides for connection of the number 3 tail rotor drive shaft to the main transmission.

3.16.2 Defects. This inspection is used to verify crack indications found visually on the main transmission tail rotor

drive flange. No cracks are allowed.

3.16.3 Primary Method. Magnetic Particle.

3.16.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

3.16.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main

transmission tail rotor drive flange removed in accordance with the applicable technical manuals listed in Table 1-1.

3.16.3.3 Access. Not applicable.

3.16.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3-36
TM 1-1520-264-23

3.16.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8;

3.16.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 3-16.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the 

media momentarily before removing the current. Current should be applied for no more than five 

seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 3.16.3.8.

f. Repeat steps a. through e. for positions 2 and 3.

3.16.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.16.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

3.16.4 Backup Method. None required.

Figure 3-16. Main Transmission Tail Rotor Drive Flange

3-37
TM 1-1520-264-23

3.16.5 System Securing. Clean the main transmission tail rotor drive flange thoroughly to remove all residual

magnetic particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main

transmission tail rotor drive flange requires installation in accordance with the applicable technical manuals listed in

Table 1-1.

3.17 MAIN ROTOR GEARSHAFT DRIVE GEAR TEETH (MT).

3.17.1 Description (Figure 3-1 . Index No. 17). The main rotor gearshaft is a semi-floating drive shaft mounted inside

the static mast. The main rotor gearshaft transmits power from the main transmission to drive the main rotor.

3.17.2 Defects. This inspection is used to verify crack indications found visually on the main rotor gearshaft drive gear

teeth. No cracks are allowed.

3.17.3 Primary Method. Magnetic Particle.

3.17.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

3.17.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main rotor

gearshaft drive gear teeth removed in accordance with the applicable technical manuals listed in Table 1-1.

3.17.3.3 Access. Not applicable.

3.17.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.17.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.17.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 3-17.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the 

media momentarily before removing the current. Current should be applied for no more than five 

seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 3.17.3.8.

f. Repeat steps a. through e. for position 2.

3-38
TM 1-1520-264-23

NDI_AH-64_F3_17

Figure 3-17. Main Rotor Gearshaft Drive Gear Teeth

3-39
TM 1-1520-264-23

3.17.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.17.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

3.17.4 Backup Method. None required.

3.17.5 System Securing. Clean the main rotor gearshaft thoroughly to remove all residual magnetic particle media.

Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main rotor gearshaft requires

installation in accordance with the applicable technical manuals listed in Table 1-1.

3.18 MAIN ROTOR MAST SUPPORT BASE (ET).

3.18.1 Description (Figure 3-1. Index No. 18). The main rotor mast support base is located in the center fuselage

area, underneath the main rotor components. It is attached to four transmission rotor support assemblies.

3.18.2 Defects. This inspection is used to verify crack indications found visually on the rotor support mast support

base. No cracks are allowed.

3.18.3 Primary Method. Eddy Current.

3.18.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

3.18.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main rotor station mast shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

3.18.3.3 Access. Access is through panels (Figure 1-4, Items L200 and R200).

3.18.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3-40
TM 1-1520-264-23

3.18.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII

Frequency F1 - 200 KHz F2 -off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3.18.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-18.

Figure 3-18. Main Rotor Mast Support Base

3-41
TM 1-1520-264-23

a. Place probe on a good area in the inspection location-and null. Adjust phase as required

to obtain horizontal lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.18.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 3.18.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

3.18.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.18.4 Backup Method. None required.

3.18.5 System Securing. The main rotor mast support base, if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

3.19 INTERMEDIATE GEARBOX (Et).

3.19.1 Description (Figure 3-1. Index No. 19). The intermediate gearbox transmits power from the main transmission

to the tail rotor gearbox. The intermediate gearbox is mounted on the vertical stabilizer.

3.19.2 Defects. This inspection is used to verify crack indications found visually on the intermediate

gearbox. No cracks are allowed.

3.19.3 Primary Method. Eddy Current.

3.19.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)

g. Teflon Tape, refer to Table 1-8

h. Aircraft Marking Pencil, refer to Table 1-8

3-42
TM 1-1520-264-23

3.19.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the intermediate gearbox shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

3.19.3.3 Access. Access to the intermediate gearbox is through the vertical stabilizer fairing (Figure 1-4, Items L510

and R510).

3.19.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.19.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII

Frequency F1 - 200 KHz F2 -off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure

1-7.)

3.19.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-19.

NOTE

The intermediate gearbox contains a higher conductivity magnesium which will require the use of the

aluminum test block when performing inspections in these areas, refer to paragraph 1.4.11.4, Sorting

Metal Using Eddy Current, to determine what test block is best suited for this inspection.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

3-43
TM 1-1520-264-23

Figure 3-19. Intermediate Gearbox

3-44
TM 1-1520-264-23

NOTE

Either probe identified in paragraph 3.19.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 3.19.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

3.19.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.19.4 Backup Method. None required.

3.19.5 System Securing. The intermediate gearbox, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

3.20 INTERMEDIATE GEARBOX RETAINERS (ET).

3.20.1 Description (Figure 3-1. Index No. 20). The intermediate gearbox retainers maintain the bearings and seals

within the intermediate gearbox assembly.

3.20.2 Defects. This inspection is used to verify crack indications found visually on the intermediate gearbox

retainers. No cracks are allowed.

3.20.3 Primary Method. Eddy Current.

3.20.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

3.20.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the intermediate gearbox retainers shall be removed in accordance

with the applicable technical manuals listed in Table 1-1.

3.20.3.3 Access. Access is through the vertical stabilizer fairings (Figure 1-4, Items R510 and L51 0).

3.20.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3-45
TM 1-1520-264-23

3.20.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19eII

Frequency F1 - 200 KHz F2 -off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure

1-7.)

3.20.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-20.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.20.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 3.20.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

3.20.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

3.20.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

3.20.5 System Securing. The intermediate gearbox retainers, if removed, require installation in accordance with the

applicable technical manuals listed in Table 1-1.

3-46
TM 1-1520-264-23

NDI_AH-4_F3_20

Figure 3-20. Intermediate Gearbox Retainers

3-47
TM 1-1520-264-23

3.21 INTERMEDIATE GEARBOX FLANGE AND SHOULDERED SHAFT (MT).

3.21.1 Description (Figure 3-1. Index No. 21). The intermediate gearbox flange and shouldered shaft is an externally

splined shaft which is connected to the intermediate gearbox and the number 6 tail rotor drive shaft.

3.21.2 Defects. T his inspection is used to verify crack indications found visually on the intermediate gearbox flange and

shouldered shaft. No cracks are allowed.

3.21.3 Primary Method. Magnetic Particle.

3.21.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

3.21.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the

intermediate gearbox flange and shouldered shaft removed in accordance with the applicable technical manuals listed in

Table 1-1.

3.21.3.3 Access. Not applicable.

3.21.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.21.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.21.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the

orientation of possible cracks. Positions required for this inspection are illustrated in Figure 3-21.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 3.21.3.8.

f. Repeat steps a. through e. for positions 2 through 5.

3-48
TM 1-1520-264-23

Figure 3-21. Intermediate Gearbox Flange and Shouldered Shaft

3.21.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.21.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

3.21.4 Backup Method. None required.

3.21.5 System Securing. Clean the intermediate gearbox flange and shouldered shaft thoroughly to remove all residual

magnetic particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The

intermediate gearbox flange and shouldered shaft require installation in accordance with the applicable technical

manuals listed in Table 1-1.

3.22 TAIL ROTOR GEARBOX (ET).

3.22.1 Description (Figure 3-1. Index No. 22). The tail rotor gearbox transmits power from the intermediate gearbox to

the tail rotor head while changing the drive angle 900. The tail rotor gearbox is mounted on the vertical stabilizer.

3.22.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor gearbox. No cracks

are allowed.

3-49
TM 1-1520-264-23

3.22.3 Primary Method. Eddy Current.

3.22.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)

g. Teflon Tape, refer to Table 1-8

h. Aircraft Marking Pencil, refer to Table 1-8

3.22.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the tail rotor gearbox shall be removed in accordance with

the applicable technical manuals listed in Table 1-1.

3.22.3.3 Access. Access is through the tail rotor transmission fairings (Figure 1-4, Items L540 and L546).

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands and restraint equipment when

working above 10 feet on helicopter in a nontactical environment. Otherwise, personnel injury could result from

accidental falls.

3.22.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.22.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 560

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos -20%

3-50
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure

1-7.)

3.22.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-22.

NOTE

The tail rotor gearbox contains a higher conductivity magnesium which will require the use of the aluminum test block

when performing inspections in these areas, refer to paragraph 1.4.11.4, Sorting Metal Using Eddy Current, to determine

what test block is best suited for this inspection.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.22.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 3.22.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

3.22.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.22.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

3.22.5 System Securing. The tail rotor gearbox, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

3.23 TAIL ROTOR GEARBOX SHOULDERED SHAFT (MT).

3.23.1 Description (Figure 3-1. Index No. 23). The tail rotor gearbox shouldered shaft is an externally splined shaft

which connects the tail rotor gearbox to the number 6 tail rotor drive shaft.

3.23.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor gearbox shouldered

shaft. No cracks are allowed.

3.23.3 Primary Method. Magnetic Particle.

3-51
TM 1-1520-264-23

NDI_AH64_F3_22

Figure 3-22. Tail Rotor Gearbox

3-52
TM 1-1520-264-23

3.23.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

3.23.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the tail rotor

gearbox shouldered shaft removed in accordance with the applicable technical manuals listed in Table 1-1.

3.23.3.3 Access. Not applicable.

3.23.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.23.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.23.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. Positions required for this inspection are illustrated in Figure 3-23.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 3.23.3.8.

f. Repeat steps a. through e. for positions 2 through 4.

3.23.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.23.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

3-53
TM 1-1520-264-23

Figure 3-23. Tail Rotor Gearbox Shouldered Shaft

3.23.4 Backup Method. None required.

3.23.5 System Securing. Clean the tail rotor gearbox shouldered shaft thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The tail rotor

gearbox shouldered shaft requires installation in accordance with the.

applicable technical manuals listed in Table 1-1.

3.24 TAIL ROTOR GEARBOX RETAINERS (ET).

3.24.1 Description (Figure 3-1. Index No. 24). The tail rotor gearbox retainers maintain the pinion gear and bearings

within the tail rotor gearbox.

3.24.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor gearbox retainers. No

cracks are allowed.

3.24.3 Primary Method. Eddy Current.

3.24.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°

 1/2 inch drop

d. Cable Assembly

3-54
TM 1-1520-264-23

e. Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

3.24.3.2 Preparation of Helicopter. The helicopter shal l be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the tail rotor gearbox retainers shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

3.24.3.3 Access. Access is through the tail rotor transmission fairing (Figure 1-4, Item L540).

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands

and restraint equipment when working above 10 feet on helicopter in a nontactical

environment. Otherwise, personnel injury could result from accidental falls.

3.24.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

3.24.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e1.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe is

passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

3-55
TM 1-1520-264-23

3.24.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 3-24.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 3.24.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 3.24.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

3.24.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.24.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

3.24.5 System Securing. The tail rotor gearbox retainers, if removed, require installation in accordance with the

applicable technical manuals listed in Table 1-1.

3.25 TAIL ROTOR GEARBOX FORWARD AND AFT STRUT (MT).

3.25.1 Description (Figure 3-1. Index No. 25). The tail rotor gearbox forward and aft struts are connected to the tail rotor

gearbox and the vertical stabilizer to provide structural support for the tail rotor gearbox assembly.

3.25.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor gearbox forward and

aft strut. No cracks are allowed.

3.25.3 Primary Method. Magnetic Particle.

3.25.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Ydke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

3-56
TM 1-1520-264-23

NDI_AH64_F324

Figure 3-24. Tail Rotor Gearbox Retainers

3-57
TM 1-1520-264-23

3.25.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using applicable positions of this procedure. If required, the tail rotor gearbox forward and

aft strut shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

3.25.3.3 Access. Access is through the tail rotor transmission fairings (Figure 1-4, Items L540 and L546). If the strut is

removed, the bearing surfaces shall be marked.

3.25.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands

and restraint equipment when working above 10 feet on helicopter in a nontactical

environment. Otherwise, personnel injury could result from accidental falls.

3.25.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.25.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 3-25.

Figure 3-25. Tail Rotor Gearbox Forward and Aft Strut

3-58
TM 1-1520-264-23

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 3.25.3.8.

f. Repeat steps a. through e. for position 3-25..

3.25.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.25.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

3.25.4 Backup Method. None required.

3.25.5 System Securing. Clean the tail rotor gearbox forward and aft strut thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The tail rotor

gearbox forward and aft strut, if removed, require installation in accordance with the applicable technical manuals listed

in Table 1-1.

3.26 TAIL ROTOR GEARBOX FORWARD AND AFT STRUT FITTINGS (MT).

3.26.1 Description (Figure 3-1. Index No. 26). The tail rotor gearbox forward and aft strut fittings provide for attachment

of the forward and aft struts to the vertical stabilizer.

3.26.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor gearbox forward and

aft strut fittings. No cracks are allowed.

3.26.3 Primary Method. Magnetic Particle.

3.26.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

3-59
TM 1-1520-264-23

3.26.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using applicable positions of this procedure. If required, the tail rotor gearbox forward and

aft strut fittings shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

3.26.3.3 Access. Access is through the tail rotor transmission fairing (Figure 1-4, Item L546).

3.26.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

Maintenance Platforms/Workstands

Use only appropriate platforms, workstands, or other approved locally procured stands

and restraint equipment when working above 10 feet on helicopter in a nontactical

environment. Otherwise, personnel injury could result from accidental falls.

3.26.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

3.26.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. Positions required for this inspection are illustrated in Figure 3-26.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 3.26.3.8.

f. Repeat steps a. through e. for position 2.

3.26.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

3.26.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

3.26.4 Backup Method. None required.

3.26.5 System Securing. Clean the tail rotor gearbox forward and aft strut fittings thoroughly to remove all residual

magnetic particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The tail

rotor gearbox forward and aft strut fittings, if removed, require installation in accordance with the applicable technical

manuals listed in Table 1-1.

3-60
TM 1-1520-264-23

NDIAH4_F3_26

Figure 3-26. Tail Rotor Gearbox Forward and Aft Strut Fittings

3-61
TM 1-1520-264-23

3.27 MAIN ROTOR HEAD (HUB) (ET).

3.27.1 Description (Figure 3-1. Index No. 27). Refer to procedure 2.11 for inspection procedure of the main rotor head

(hub).

3.28 MAIN ROTOR SUPPORT MAST (MT).

3.28.1 Description (Figure 3-1. Index No. 28). Refer to paragraph 2.8 for inspection procedure for the main rotor

support mast.

3-62
TM 1-1520-264-23

SECTION IV

AIRFRAME AND LANDING GEAR SYSTEM

4. GENERAL.

4.1 CONTENTS. The airframe and landing gear system inspection items covered in this section are those critical items

of the AH-64A helicopter listed in the Airframe and Landing Gear System Inspection Index (Table 4-1). Corresponding

inspection figures and applicable text paragraphs are listed opposite each inspection item. The index number for each

item may be used to locate it in Figure 4-1.

Table 4-1. Airframe and Landing Gear System Inspection Index

Index Inspection Paragraph Figure

Number Nomenclature Method Number Number

2 Fuselage and Empennage Access Doors, Covers, ET 4.2 4-2

Panels, Skins, and Fairings - Metal

3 Honeycomb Core Fuselage Panels, Vertical Fin, BT 4.3 4-3

etc.

4 Fluid in Honeycomb Core Fuselage Panels, RT 4.4 4-4

Vertical Fin, etc.

5 Fittings, Castings, and Forgings ET 4.5 4-5

6 Transmission Deck ET 4.6 4-6

7 Empennage Frame Assemblies F.S. 530 and F.S. ET 4.7 4-7

547 and Attached Stringers

8 Fuselage Support Holes ET 4.8 4-8

9 Gun and Ammo Support Mount Pads ET 4.9 4-9

10 Main Landing Gear Shock Strut Support MT 4.10 4-10

11 Main Landing Gear Cross Tube Mounting Points ET 4.11 4-11

*12 Rotor Support Mixer Assembly and Mounting MT 4.12 4-12

Surfaces

*13 Rotor Mixer Support Assembly Bolt MT 4.13 4-13

*14 Transmission Rotor Support Strut Assemblies ET 4.14 4-14

15 Nacelle Carry-Through Post Assembly ET 4.15 4-15

16 Wing Attachment Fittings on Wing and Fuselage ET 4.16 4-16

17 Wing Rack Attachment Points/Mounts ET 4.17 4-17

18 TADS/PNVS Support Fitting ET 4.18 4-18

19 Vertical Stabilizer Lugs ET 4.19 4-19

20 Vertical Stabilizer Barrel Nuts MT 4.20 4-20

4-1
TM 1-1520-264-23

Table 4-1. Airframe and Landing Gear Group Inspection Index - Continued

Index Inspection Paragraph Figure

Number Nomenclature Method Number Number

21 Horizontal Stabilator Actuator Fitting ET 4.21 4-21

22 Engine Access and Ventilation Door Assembly Rig PT 4.22 4-22

Connecting Link

23 Aft Inboard Engine Mount Support ET 4.23 4-23

24 Engine Nacelle Strut Attachment Area ET 4.24 4-24

25 Main Landing Gear Trailing Arms. MT 4.25 4-25

26 Main Landing Gear Wheels ET 4.26 4-26

27 Main Landing Gear Shock Strut Housing, Piston, MT 4.27 4-27

and Rod Ends

28 Main Landing Gear Lower Structural Support MT 4.28 4-28

29 Main Landing Gear. Jack Pad Adapter MT 4.29 4-29

30 Main Landing Gear Trailing Arm Cross Tube MT 4.30 4-30

31 Main Landing Gear Shock Strut Mount Shaft MT 4.31 4-31

32 Tail Landing Gear Fork ET 4.32 4-32

33 Tail Wheel ET 4.33 4-33

34 Tail Landing Gear Shock Strut MT 4.34 4-34

35 Tail Landing Gear Trailing Arms ET 4.35 4-35

36 Tail Landing Gear Actuating Cylinder Assembly ET 4.36 4-36

37 Brake System Components PT 4.37 4-37

38 General Helicopter Attaching Hardware MT 4.38 4-38

NOTE: *Indicates Flight Safety Part.

4-2
TM 1-1520-264-23

Figure 4-1. Airframe and Landing Gear System (Sheet 1 of 2)

4-3
TM 1-1520-264-23

NDI_AH4_F4_1_2

Figure 4-1. Airframe and Landing Gear System (Sheet 2 of 2)

4-4
TM 1-1520-264-23

4.2 FUSELAGE AND EMPENNAGE A CCESS DOORS, COVERS, PANELS, SKINS, AND

FAIRINGS- METAL (ET).

4.2.1 Description (Figure 4-1. Index No. 2). This inspection is applicable to all access doors, covers, panels, skins, and

fairings constructed of nonferrous metallic materials.

4.2.2 Defects. Defects may occur anywhere on the surface of the components listed above. The primary purpose of

this inspection is for: (1) confirmation of crack indications identified by visual inspections; (2) verifications that dents,

scratches, or gouges do not conceal cracks; and (3) locating the ends of confirmed cracks so that stop drilling may be

performed. No cracks are allowed.

4.2.3 Primary Method. Eddy Current.

4.2.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Reference Block, three-notched magnesium (0.008, 0.020, and 0.040 EDM notches)

g. Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)

h. Teflon Tape, refer to Table 1-8

i. Aircraft Marking Pencil, refer to Table 1-8

4.2.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. If required, access

doors, covers, panels, and fairings shall be removed in accordance with the applicable technical manuals listed in Table

1-1.

4.2.3.3 Access. The components are generally accessed from outside the helicopter.

4.2.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.2.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - (56° aluminum and magnesium) (30° titanium)

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

4-5
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows: .

(1) Null probe on the appropriate test block - aluminum test block for aluminum alloys, the magnesium test block

for magnesium alloys, or the titanium test block for titanium and non-ferromagnetic stainless steel.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4.2.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-2.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.2.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 4.2.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

4.2.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.2.4 Backup Method. None required.

4.2.5 System Securing. The access doors, covers, panels, and fairings, if removed or opened, require installation or

securing in accordance with the applicable technical manuals listed in Table 1-1.

4.3 HONEYCOMB CORE FUSELAGE PANELS, VERTICAL FIN, ETC. (BT).

4.3.1 Description (Figure 4-1. Index No. 3). This inspection is applicable to parts or components made of

metallic/nonmetallic skins bonded to metallic/ nonmetallic cores and laminations of facings of metal or fiberglass panels.

The structural assembly components identified for inspection are: forward fuselage honeycomb panels, decking

honeycomb panels, and vertical fin honeycomb panels.

4.3.2 Defects. Perform the NDI method contained herein on the components listed above for the purpose of

verification of void damage identified by visual inspection. Void damage may occur anywhere on either side of bonded

panels as a result of mechanical damage (dents, punctures, scratches, etc.) or fluid intrusion/corrosion.

NOTE

A void is defined as an unbonded area that is suppose to be bonded. Many subdefinitions are given

such as bond separation, delimitation, lack of adhesive, gas pocket, misfit, etc. This procedure makes

no distinction among these instead grouping under the general term "void."

4-6
TM 1-1520-264-23

NDI_AH64_F4_2

Figure 4-2. Fuselage and Empennage Access Doors, Covers, Panels,

Skins, and Fairings- Metal

4-7
TM 1-1520-264-23

4.3.3 Primary Method. Bond Testing.

4.3.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Bond Test Unit

b. Probe Mechanical Impedance Analysis

c. Probe Holder

d. Cable Assembly

e. Test Block, metal honeycomb with skin thickness closest to that of the panel to be inspected (refer to Appendix

C)

f. Test Block, Composite Defect Standard #1

g. Test Block, Composite Defect Standard #3

h. Teflon Tape, consumable material, refer to Table 1-8

i. Aircraft Marking Pencil, refer to Table 1-8

4.3.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance in accordance with

applicable technical manuals listed in Table 1-1.

4.3.3.3 Access. Not applicable.

4.3.3.4 Preparation of Part. The components shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.3.3.5 NDI Equipment Settings. Refer to Bond Testing Equipment, paragraph 1.4.6.1.

a. Attach cable and probe to Bondmaster. Protect probe with Teflon tape and install in probe holder.

b. Turn on Bondmaster, press SPCL, and make the following adjustments.

H Pos -40%

VPos - 80%

PHASE REF - 0

DRIVE - MID

c. Press SET and select DISPLAY - PHASE.

d. Place probe on good area of test block and press GOOD PART. Do this several times while moving the probe to

different spots in the good area of the test block. Note the video signature for each. Select and enter a

representative good area by pressing GOOD PART one last time.

e. Place probe on void area of the test block and press BAD PART. Do this several times while moving the probe

slightly to different positions within the void area. Select and enter a position that gives a strong difference

between good and void areas. Use DIFF soft key to observe difference between good and bad areas of test

block.

4-8
TM 1-1520-264-23

NOTE

If during setup the flying spot deflects upward or to the side when the probe passes over

the bad part, instead of the desired down deflection toward the alarm box, Press SPCL

and toggle to a different phase setting (90,180, or 270), and repeat d. and e. Continue to

try phase setting until the flying spot moves in the desired down direction.

f. Place probe on good area of test block and press RUN. Flying spot should be near the top center of the ACTIVE

screen. If not, press NULL. Slide probe from good to void area and note response from flying spot. This response

should provide both amplitude (vertical) and phase (horizontal) movement. The default gate/alarm setting may

be incorrect for this setup. Turn off or reset gate/alarm as desired.

g. The Bondmaster is programmed to automatically set test parameters to a start-up or initial bond test. By

following the steps outlined above, adjustments to the FREQ, GAIN, and ALARM can help to refine the

selectivity in locating defects among differing composite materials.

4.3.3.6 Inspection Procedure. Refer to Bond Test Method, paragraph 1.4.6 and inspection areas shown in Figure 4-3.

Place probe in location where test for void is desired and press NULL. Move probe from good to suspect area and note

response. A strong amplitude change and phase shift similar to the test block is indicative of a void.

Figure 4-3. Honeycomb Core Fuselage Panels, Vertical Fin, etc.

4-9
TM 1-1520-264-23

NOTE

This setup is very sensitive to thin skin-to-core bonding. If the panel skin is 0.020 inch

thick or less, move the probe slowly over the skin and note the slight amplitude change

(bounce) as the probe senses alternately the honeycomb cell nodes and cell walls. Be

sure of panel configuration. Panel edges and attachment points may not be bonded

structure and do not normally contain honeycomb. These areas will respond similarly to

voids with the Bondmaster. Panels having rigidified skins are more easily scanned using

wide Teflon tape on the probe holder.

4.3.3.7 Marking and Recording of Inspection Results. Mark and record as required by paragraph 1.3.

NOTE

Attention shall be directed to accurately marking the boundaries of all voids on both

sides of the panel. These markings will be needed to determine acceptance/rejection

criteria in accordance with the applicable technical manuals listed in Table 1-1.

4.3.4 Backup Method. None required.

4.3.5 System Securing. Reinstall acceptable panels that were removed for inspection in accordance with the

applicable technical manual listed in Table 1-1.

4.4 FLUID IN HONEYCOMB CORE FUSELAGE PANELS, VERTICAL FIN, ETC. (RT).

4.4.1 Description (Figure 4-1. Index No. 4). This inspection is applicable to parts or components made of

metallic/nonmetallic skins bonded to metallic/nonmetallic cores and laminations of facings of metal or fiberglass panels.

The structural assembly components identified for inspection are: forward fuselage honeycomb panels, decking

honeycomb panels, and vertical fin honeycomb panels.

4.4.2 Defects. Fluid in honeycomb core of fuselage panels, vertical fin, etc.

4.4.3 Primary Method. Radiography.

Radiation Hazard

Assure compliance with all applicable safety precautions set forth in TM 55-1500-335-23

(Nondestructive Inspection Methods manual) listed in Table 1-1. A hazard associated

with exposure to ionizing radiation is that serious injury can be inflicted without pain,

burning, or other sense of discomfort during the exposure period. Radiation protection

shall be utilized in accordance with AR40-14/DLAR 1000.28.

4.4.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. X-ray Unit

b. Tripod, X-ray tubehead stand

4-10
TM 1-1520-264-23

c. Film Processor

d. Film, Ready Pack 8 inch x 10 inch

e. Marking Material, refer to Table 1-8

4.4.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenancein accordance with

applicable technical manuals listed in Table 1-1.

4.4.3.3 Access. Not applicable.

4.4.3.4 Preparation of Part. The identified area of interest shall be thoroughly cleaned. Refer to Preparation of Part or

Area for NDI, paragraph 1.4.4..

4.4.3.5 NDI Equipment Settings.

a. Refer to Radiographic (X-ray) method, paragraph 1.4.10.

b. Typical equipment settings, inspection and exposure data are given in Figure 4-4.

4.4.3.6 Inspection Procedure. Inspect designated areas, refer to Figure 4-4 for typical fluid entrapment and source/film

placement.

a. Position film and desired nameplate data for exposure number 1.

b. Position X-ray tubehead for exposure number 1.

c. Set X-ray unit to the values given in the Radiographic Inspection Data chart for exposure number 1.

d. Make exposure number 1.

e. Remove exposed film.

f. Repeat inspection procedure (steps a. through e. above) for each exposure.

g. Process and interpret film for defects as noted in paragraph 4.4.2 and as shown in Figure 4-4.

4.4.4 Backup Method. None required.

4.4.5 System Securing. The inspected area shall be cleaned as necessary. Refer to Post Cleaning and Restoration of

Part or Area After NDI, paragraph 1.4.6.1.

4-11
TM 1-1520-264-23

Figure 4-4. Fluid in Honeycomb Core Fuselage Panels, Vertical Fin, etc. (Sheet 1 of 2)

4-12
TM 1-1520-264-23

Figure 4-4. Fluid in Honeycomb Core Fuselage Panels, Vertical Fin, etc. (Sheet 2 of 2)

4-13
TM 1-1520-264-23

4.5 FITTINGS, CASTINGS, AND FORGINGS (ET).

4.5.1 Description (Figure 4-1. Index No. 5). Fittings, castings, and forgings made of nonferrous material can be found

throughout the helicopter. Those items generally serve as structural attaching points, stiffening points, and equipment

mounts.

4.5.2 Defects. Cracks may occur anywhere on the surface of these components. The primary purpose of this

inspection is for: (1) confirmation of crack indications identified by visual inspections; (2) verification that dents,

scratches, or gouges do not conceal cracks; and (3) ensuring that no cracks remain after any blending is completed

(when allowed). No cracks are allowed.

4.5.3 Primary Method. Eddy Current.

4.5.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.5.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection for

cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of the

installed part using this procedure. If required, the fittings, castings, and forgings shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

4.5.3.3 Access. Accessibility of fittings, castings, and forgings varies considerably. Refer to Figure 1-4 and Table 1-2 to

locate applicable access provisions.

4.5.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.5.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos -20%

4-14
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4.5.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-5.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.5.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 4.5.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

Figure 4-5. Fittings, castings, and Forgings

4-15
TM 1-1520-264-23

4.5.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.5.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

4.5.5 System Securing. The fittings, castings, and forgings, if removed, require installation in accordance with the

applicable technical manuals listed in Table 1-1.

4.6 TRANSMISSION DECK (ET).

4.6.1 Description (Figure 4-1. Index No. 6). The transmission deck is found below the transmission. It separates the

transmission compartment from the lower-fuselage. The transmission struts are affixed directly to the transmission deck.

The catwalk, which is over the aft portion of the deck, is a four-piece platform (one piece includes a folding structure) that

covers the drive shaft area.

4.6.2 Defects. This inspection is used to verify crack indications found visually on the transmission deck. No cracks

are allowed.

4.6.3 Primary Method. Eddy Current.

4.6.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.08, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.6.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection for

cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of the

installed part using this procedure. If required, the catwalk shall be removed in accordance with the applicable technical

manuals listed in Table 1-1.

4.6.3.3 Access. Access is through the main rotor transmission panel, hydraulic heat exchanger fairings, and deck area

doors and fairings (Figure 1-4, Items T250L, T250R, T290L, L200, R200, and L325).

4.6.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4-16
TM 1-1520-264-23

4.6.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e".

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4.6.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-6.

Figure 4-6. Transmission Deck

4-17
TM 1-1520-264-23

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.6.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 4.6.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

4.6.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.6.4 Backup Method. None required.

4.6.5 System Securing. The catwalk, if removed, requires installation in accordance with the applicable technical

manuals listed in Table 1-1.

4.7 EMPENNAGE FRAME ASSEMBLIES F.S. 530 AND F.S. 547 AND ATTACHED STRINGERS (ET).

4.7.1 Description (Figure 4-1. Index No. 7). The frame assemblies are located within the tailboom and form the four

attaching points for the vertical stabilizer. Each of the attaching points protrudes through the tailboom skin at two points

at F.S. 530 and two points at F.S. 547. The stringers are attached to the inner surface of the tailboom skin along the

length of the stringers and are sandwiched between the skin and the frame flanges.

4.7.2 Defects. Defects can occur anywhere on the surface of the empennage frame assemblies and attached

stringers. No cracks are allowed.

4.7.3 Primary Method. Eddy Current.

4.7.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.7.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance.

4-18
TM 1-1520-264-23

4.7.3.3 Access. Access to the aft portions of F.S. 530, all stringers aft of F.S. 530, and both forward and aft portions of

F.S. 547 is by removal of covers R/L 545. Access to all stringers forward of F.S..530 and the forward portion of the F.S.

530 frame is by entry into the tailboom at L/R 330 and crawling aft.

4.7.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.7.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4.7.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-7.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.7.3.1 may be used depending primarily on the ease of accessibility and

user friendliness. If the probes are changed, steps 4.7.3.5 b.(1), (2), and (3) shall be repeated each time a

change is made.

4.7.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.7.4 Backup Method. None required.

4.7.5 System Securing. Secure applicable access covers.

4-19
TM 1-1520-264-23

Figure 4-7. Empennage Frame Assemblies F.S. 530 and F.S. 547

and Attached Stringers

4-20
TM 1-1520-264-23

4.8 FUSELAGE SUPPORT HOLES (ET).

4.8.1 Description (Figure 4-1. Index No. 8). The fuselage support holes to be checked are located inside the

helicopter in the wing mounting area. The holes are used to mount the wing barrel nuts.

4.8.2 Defects. Defects can occur anywhere on the surface of the fuselage support holes. No cracks are allowed.

4.8.3 Primary Method. Eddy Current.

4.8.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°

 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.8.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the wings,

ammunition storage magazine, and the barrel nuts removed in accordance with the applicable technical manuals listed in

Table 1-1.

4.8.3. Access. Not applicable.

4.8.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.8.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e 11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical si gnal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4-21
TM 1-1520-264-23

4.8.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-8.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.8.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 4.8.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

4.8.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.8.4 Backup Method. None required.

4.8.5 System Securing. The wings, ammunition storage magazine, and barrel nuts require installation in accordance

with the applicable technical manuals listed in Table 1-1.

4.9 GUN AND AMMO SUPPORT MOUNT PADS (ET).

4.9.1 Description (Figure 4-1. Index No. 9). There are four gun and ammo support mount pads, two

located in the forward fuselage area, where they support the forward fuselage gun, and two in the aft fuselage, where

they function as the ammo support aft mount pads.

4.9.2 Defects. Defects can occur anywhere in, or on the surface of, the bushing bore areas.

4.9.3 Primary Method. Eddy Current.

4.9.3.1 NDI Equipment and Materials.(Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.9.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection for

cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of the

installed part using this procedure. If required, the gun and ammo support mount pads shall be removed in accordance

with the applicable technical manuals listed in Table 1-1.

4-22
TM 1-1520-264-23

Figure 4-8. Fuselage Support Holes

4-23
TM 1-1520-264-23

4.9.3.3 Access. Access is through the gun turret bay fairings (Figure 1-4, Items B90 and B120).

4.9.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.9.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e 11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4.9.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-9.

a. Place probe on a good area in the inspection location and null. Adjust phase as requir ed to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.9.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 4.9.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

4.9.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.9.4 Backup Method. None required.

4.9.5 System Securing. The gun and ammo support mount pads, if removed, require installation in accordance with

the applicable technical manuals listed in Table 1-1.

4-24
TM 1-1520-264-23

Figure 4-9. Gun and Ammo Support Mount Pads

4-25
TM 1-1520-264-23

4.10 MAIN LANDING GEAR SHOCK STRUT SUPPORT (MT).

4.10.1 Description (Figure 4-1. Index No. 10). The main landing gear shock strut support mounts the main landing

gear shock strut to the fuselage. Left and right units are similar.

4.10.2 Defects. This inspection is used to verify crack indications found visually on the main landing gear shock strut

support. No cracks are allowed.

4.10.3 Primary Method. Magnetic Particle.

4.10.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

4.10.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main

landing gear shock strut support removed in accordance with the applicable technical manuals listed in Table 1-1.

4.10.3.3 Access. Not applicable.

 4.10.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.10.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.10.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. Positions required for this inspection are illustrated in Figure 4-10.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five

seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 4.10.3.8.

f. Repeat steps a. through e. for positions 2 through 5.

4.10.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4-26
TM 1-1520-264-23

Figure 4-10. Main Landing Gear Shock strut Support

4.10.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

4.10.4 Backup Method. None required.

4.10.5 System Securing. Clean the main landing gear shock strut support thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main landing

gear shock strut support, if removed, requires installation in accordance with the applicable technical manuals listed in

Table 1-1.

4.11 MAIN LANDING GEAR CROSS TUBE MOUNTING POINTS (ET).

4.11.1 Description (Figure 4-1. Index No. 11). The main landing gear cross tube is supported by mounts that are

integral to the helicopter fuselage.

4.11.2 Defects. This inspection is used to verify crack indications found visually on the mounting point area. No cracks

are allowed.

4.11.3 Primary Method. Eddy Current.

4-27
TM 1-1520-264-23

4.11.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.11.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the main landing gear cross tube shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

4.11.3.3 Access. Not applicable.

4.11.3.4 Preparation of Part. Thepart shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.11.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure

1-7.)

4-28
TM 1-1520-264-23

4.11.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-11.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.11.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 4.11.3.5 b. (1), (2), and (3) shall be repeated each time a change is made.

4.11.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph

1.3.

4.11.4 Backup Method. None required.

4.11.5 System Securing. The main landing gear cross tube, if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

4.12 ROTOR SUPPORT MIXER ASSEMBLY AND MOUNTING SURFACES (MT).

4.12.1 Description (Figure 4-1. Index No. 12). The rotor support mixer assemblies are located on the main rotor

support base.

4.12.2 Defects. This inspection is used to verify crack indications found visually on the rotor support mixer assembly

and mounting surfaces. No cracks are allowed.

4.12.3 Primary Method. Magnetic Particle.

4.12.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4-29
TM 1-1520-264-23

NDI AH64 F4 11

Figure 4-11. Main Landing Gear Cross Tube Mounting Points

4-30
TM 1-1520-264-23

4.12.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the rotor support mixer assembly shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

4.12.3.3 Access. Access is through the main transmission access panels (Figure 1-4, Items L200 and R200).

4.12.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.12.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.12.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. Positions required for this inspection are illustrated in Figure 4-12.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five

seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 4.12.3.8.

f. Repeat steps a. through e. for position 2.

Figure 4-12. Rotor Support Mixer Assembly and Mounting Surfaces

4-31
TM 1-1520-264-23

4.12.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.12.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

4.12.4 Backup Method. None required.

4.12.5 System Securing. Clean the rotor support mixer assembly and mounting surfaces thoroughly to remove all

residual magnetic particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16.

The rotor support mixer assembly, if removed, requires installation in accordance with the applicable technical manuals

listed in Table 1-1.

4.13 ROTOR MIXER SUPPORT ASSEMBLY BOLT (MT).

4.13.1 Description (Figure 4-1, Index No. 13). The rotor mixer support bolt is found on the underside of the rotor

support mast support base.

4.13.2 Defects. This inspection is used to verify crack indications found visually on the rotor support mixer assembly

bolt. No cracks are allowed.

4.13.3 Primary Method. Magnetic Particle.

4.13.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4.13.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the rotor mixer

support bolt removed in accordance with the applicable technical manuals listed in Table 1-1.

4.13.3.3 Access. Not applicable.

4.13.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Prepar ation of Part or Area for NDI,

paragraph 1.4.4.

4.13.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4-32
TM 1-1520-264-23

4.13.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 4-13.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five

seconds.

d. Inspect for cracks using the black light.

4.13.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.13.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

4.13.4 Backup Method. None required.

4.13.5 System Securing. Clean the rotor mixer support bolt thoroughly to remove all residual magnetic particle media.

Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The rotor mixer support bolt

requires installation in accordance with the applicable technical manuals listed in Table 1-1.

Figure 4-13. Rotor Mixer Support Assembly Bolt

4-33
TM 1-1520-264-23

4.14 TRANSMISSION ROTOR SUPPORT STRUT ASSEMBLIES (ET).

4.14.1 Description (Figure 4-1. Index No. 14). There are eight transmission rotor support strut assemblies. They are

attached between rotor mast support base and the fuselage. They are located in the center fuselage area.

4.14.2 Defects. Defects can occur anywhere on the surface of the transmission rotor support strut assemblies. No

cracks are allowed.

4.14.3 Primary Method. Eddy Current.

4.14.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.14.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the transmission rotor support strut assemblies shall be

removed in accordance with the applicable technical manuals listed in Table 1-1.

4.14.3.3 Access. Access is from the main transmission access panels (Figure 1-4, Items L200 and R200).

4.14.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area f or NDI,

paragraph 1.4.4.

4.14.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

4-34
TM 1-1520-264-23

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4.14.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-14.

a. Place probe on a good area in the inspection location and-null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.14.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 4.14.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

4.14.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.14.4 Backup Method. None required.

4.14.5 System Securing. The transmission rotor support strut assemblies, if removed, require installation in accordance

with the applicable technical manuals listed in Table 1-1.

4.15 NACELLE CARRY-THROUGH POST ASSEMBLY (ET).

4.15.1 Description (Figure 4-1, Index No. 15). The nacelle carry-through post assembly is located beneath the catwalk

center aft panel. There are two posts, left and right.

4.15.2 Defects. Defects can occur anywhere on the surface of the nacelle carry-through post assembly. No cracks are

allowed.

4.15.3 Primary Method. Eddy Current.

4-35
TM 1-1520-264-23

Figure 4-14. Transmission Rotor Strut Assemblies

4-36
TM 1-1520-264-23

4.15.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.15.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the nacelle carry-through post assembly shall be removed

in accordance with the applicable technical manuals listed in Table 1-1.

4.15.3.3 Access. Access is through doors (Figure 1-4, Items T250L, T250R, T290L, T290R, and L325).

4.15.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.15.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4-37
TM 1-1520-264-23

4.15.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-15.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.15.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 4.15.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

4.15.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.15.4 Backup Method. None required.

4.15.5 System Securing. The nacelle carry-through post assembly, if removed, requires installation in accordance with

the applicable technical manuals listed in Table 1-1. Secure opened access doors.

4.16 WING ATTACHMENT FITTINGS ON WING AND FUSELAGE (ET).

4.16.1 Description (Figure 4-1. Index No. 16). The wing attach fittings on the wings and fuselage are located at F.S.

199.75, F.S. 214.50, and WL 139.34, and 129.2. All of the attach fittings are made from aluminum alloy.

4.16.2 Defects. This inspection is used to verify crack indications found visually on the wing attach fittings. No cracks

are allowed.

4.16.3 Primary Method. Eddy Current.

4.16.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°

 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.16.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the wing shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

4-38
TM 1-1520-264-23

Figure 4-15. Nacelle Carry-Through Post Assembly

4-39
TM 1-1520-264-23

4.16.3.3 Access. Access is through wing fairings (Figure 1-4, Items LW10, RW10, LW11, and RW11).

4.16.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.16.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4.16.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-16.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.16.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 4.16.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

4.16.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.16.4 Backup Method. None required.

4.16.5 System Securing. The wing(s), if removed, requires installation in accordance with the applicable technical

manuals listed in Table 1-1.

4-40
TM 1-1520-264-23

Figure 4-16. Wing Attachment fittings on Wing and Fuselage

4.17 WING RACK ATTACHMENT POINTS/MOUNTS (ET).

4.17.1 Description (Figure 4-1. Index No. 17). The wing rack attachment points/mounts provide a means and place

to attach the pylons, fuel tanks, and ordinance to the wings.

4.17.2 Defects. This inspection is used to verify crack indications found visually on the wing rack attachment

points/mounts. Pay particular attention to the areas around the yoke or clevis to include the hollow pin mounting area.

No cracks are allowed.

4.17.3 Primary Method. Eddy Current.

4.17.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4-41
TM 1-1520-264-23

4.17.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure in accordance with the applicable technical manuals listed in Table 1-1.

4.17.3.3 Access. Access is through the pylon nose fairing (Figure 1-4, Item P1).

4.17.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or X Area for NDI,

paragraph 1.4.4.

4.17.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4.17.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-17.

a. Place probe on a good area in the inspection location and null. Adjust phase as required t oobtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.17.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 4.17.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

4-42
TM 1-1520-264-23

Figure 4-17. Wing Rack Attachment Points/Mounts

4-43
TM 1-1520-264-23

4.17.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.17.4 Backup Method. None required.

4.17.5 System Securing. None required. Secure the pylon nose fairing.

4.18 TADS/PNVS SUPPORT FITTING (ET).

4.18.1 Description (Figure 4-1. Index No. 18). The TADS/PNVS is located at F.S. 33.50. This lower support fitting

supports and separates the TADS/PNVS from the forward cockpit area. It is constructed of aluminum alloy.

4.18.2 Defects. This inspection is used to verify crack indications found visually on the TADS/PNVS support fitting. No

cracks are allowed.

4.18.3 Primary Method. Eddy Current.

4.18.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz,90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.18.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the

TADS/PNVS removed in accordance with the applicable technical manuals listed in Table 1-1.

4.18.3.3 Access. Not applicable.

4.18.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.18.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

4-44
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtai n a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in

Figure 1-7.)

4.18.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-18.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.18.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 4.18.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

4.18.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.18.4 Backup Method. None required.

Figure 4-18. TADS/PNVS Support Fitting

4-45
TM 1-1520-264-23

4.18.5 System Securing. The TADS/PNVS support fitting requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

4.19 VERTICAL STABILIZER LUGS (ET).

4.19.1 Description (Figure 4-1. Index No. 19). The four vertical stabilizer lugs attach the vertical stabilizer to the

tailboom.

4.19.2 Defects. Defects can occur anywhere on the surface of the vertical stabilizer lugs. No cracks are allowed.

4.19.3 Primary Method. Eddy Current.

4.19.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.19.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial nspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the vertical stabilizer lugs shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

4.19.3.3 Access. Access is through the vertical stabilizer and vertical stabilizer leading edge fairings (Figure 1-4,

Items UR 510 and L/R 530).

4.19.3.4 Preparation of Part. The part shall be thoroughl y cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.19.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e"

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos -20%

4-46
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in

Figure 1-7.)

4.19.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-19.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.19.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 4.19.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

4.19.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

Figure 4-19. Vertical Stabilizer Lugs

4-47
TM 1-1520-264-23

4.19.4 Backup Method. None required.

4.19.5 System Securing. The vertical stabilizer, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

4.20 VERTICAL STABILIZER BARREL NUTS (MT).

4.20.1 Description (Figure 4-1. Index No. 20). The vertical stabilizer barrel nuts are located beneath the vertical

stabilizer lugs and may only be seen when the vertical stabilizer is removed.

4.20.2 Defects. This inspection is used to verify crack indications found visually on the vertical stabilizer barrel nuts.

No cracks are allowed.

4.20.3 Primary Method. Magnetic Particle.

4.20.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4.20.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the vertical

stabilizer barrel nuts removed in accordance with the applicable technical manuals listed in Table 1-1.

4.20.3.3 Access. Not applicable.

4.20.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.20.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.20.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The position required for this inspection is illustrated in Figure 4-20.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

4-48
TM 1-1520-264-23

Figure 4-20. Vertical Stabilizer Barrel Nuts

4.20.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.20.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

4.20.4 Backup Method. None required.

4.20.5 System Securing. Clean the vertical stabilizer barrel nuts thoroughly to remove all residual magnetic particle

media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The vertical stabilizer

requires installation in accordance with the applicable technical manuals listed in Table 1-1.

4.21 HORIZONTAL STABILATOR ACTUATOR FITTING (ET).

4.21.1 Description (Figure 4-1. Index No. 21). The horizontal stabilator actuator fitting is located on the horizontal

stabilator and provides a mounting point for the horizontal stabilator actuator.

4.21.2 Defects. Defects can occur anywhere on the surface of the actuator fitting. No cracks are allowed.

4.21.3 Primary Method. Eddy Current.

4.21.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

4-49
TM 1-1520-264-23

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.21.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the horizontal stabilator actuator shall be removed in accordance with

the applicable technical manuals listed in Table 1-1.

4.21.3.3 Access. Access is through tailboom cover (Figure 1-4, Items L545 and R545).

4.21.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.21.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB -57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos -80%

VPos -20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in

Figure 1-7.)

4.21.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-21.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

4-50
TM 1-1520-264-23

Figure 4-21. Horizontal Stabilator Actuator Fitting

NOTE

Either probe identified in paragraph 4.21.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 4.21.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

4.21.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.21.4 Backup Method. None required.

4.21.5 System Securing. The horizontal stabilator actuator requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

4.22 ENGINE ACCESS AND VENTILATION DOOR ASSEMBLY RIG CONNECTING LINK (PT).

4.22.1 Description (Figure 4-1. Index No. 22). The left and right engine ventilation door rig connecting links are the

same. They act to control the air flow into the engine nacelle to assist in controlling engine temperatures.

4.22.2 Defects. This inspection is used to verify crack indications found visually on the connecting links. No cracks

are allowed.

4.22.3 Primary Method. Fluorescent Penetrant.

4.22.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-I25135 level 3 penetrant materials shall be selected from the approved list in Table 1-8.

4-51
TM 1-1520-264-23

4.22.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the link shall be removed in accordance with the applicable technical

manuals listed in Table 1-1.

4.22.3.3 Access. Access is through doors (Figure 1-4, Items LN3 or RN3, opened).

4.22.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

4.22.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,

paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 4-22.

4.22.3.6 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.22.4 Backup Method. None required.

4.22.5 System Securing. Clean the link to remove inspection media. Refer to Post Cleaning and Restoration of Part

or Area After NDI, paragraph 1.4.16. The door assembly rig connecting link, if removed, requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

4.23 AFT INBOARD ENGINE MOUNT SUPPORT (ET).

4.23.1 Description (Figure 4-1. Index No. 93). The aft inboard engine mount supports are made of titanium and

provide support at the aft end of the engines. There are two aft engine mount supports, one on each side of the

helicopter.

4.23.2 Defects. Defects can occur anywhere on the surface of the aft inboard engine mount support. The primary

purpose of this inspection is for: (1) confirmation of crack indications previously identified by visual inspection; (2)

verification that dents, scratches, or gouges do not conceal cracks; and (3) identifying the size of confirmed cracks.

Typically, no cracks are allowed. In some cases, cracks may be allowed up to the size specified in the associated

technical manuals listed in Table 1-1.

4.23.3 Primary Method. Eddy Current.

4.23.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4-52
TM 1-1520-264-23

Figure 4-22. Engine Access and Ventilation Door Assembly Rig Connecting Link

4.23.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the engine

removed in accordance with the applicable technical manuals listed in Table 1-1.

4.23.3.3 Access. Not applicable.

4.23.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.23.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in

Figure 1-7.)

4-53
TM 1-1520-264-23

4.23.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-23.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obt ain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.23.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 4.23.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

4.23.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.23.4 Backup Method. None required.

4.23.5 System Securing. The engine requires installation in accordance with the applicable technical manuals listed

in Table 1-1.

Figure 4-23. Aft Inboard Engine Mount Support

4-54
TM 1-1520-264-23

4.24 ENGINE NACELLE STRUT ATTACHMENT AREA (ET).

4.24.1 Description (Figure 4-1. Index No. 24). The two engine nacelle struts are located inside the engine nacelle

at the rear end and above each engine. The struts and the nacelle attachment area are aluminum.

4.24.2 Defects. Defects can occur anywhere on the surface of the engine. nacelle strut attachment area. No cracks

are allowed.

4.24.3 Primary Method. Eddy Current.

4.24.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.24.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the engine nacelle strut shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

4.24.3.3 Access. Access is through the engine work platform door (Figure 1-4, Items RN 1 and LN 1).

4.24.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.24.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in

Figure 1-7.)

4-55
TM 1-1520-264-23

4.24.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-24.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.24.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 4.24.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

4.24.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.24.4 Backup Method. None required.

4.24.5 System Securing. The engine nacelle strut, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

4.25 MAIN LANDING GEAR TRAILING ARMS (MT).

4.25.1 Description (Figure 4-1. Index No. 25). The left and right main landing gear trailing arms are the largest

tubular portion of each of the landing gear assemblies. The upper end attaches to the cross tube and the lower end is the

axle.

4.25.2 Defects. This inspection is used to verify crack indications found visually on the main landing gear trailing

arms. No cracks are allowed.

4.25.3 Primary Method. Magnetic Particle.

4.25.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4-56
TM 1-1520-264-23

Figure 4-24. Engine Nacelle Strut Attachment Area

4-57
TM 1-1520-264-23

4.25.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using applicable positions of this procedure. If required, the main landing gear trailing arms shall be

removed in accordance with the applicable technical manuals listed in Table 1-1.

4.25.3.3 Access. Access is from panels (Figure 1-4, Items L140 and R140).

4.25.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.25.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.25.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 4-25.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 4.25.3.8.

f. Repeat steps a. through e. for positions 2 through 5.

4.25.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.25.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

4.25.4 Backup Method. None required.

4.25.5 System Securing. Clean the main landing gear trailing arms thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main landing

gear trailing arms, if removed, require installation in accordance with the applicable technical manuals listed in Table 1-1.

4.26 MAIN LANDING GEAR WHEELS (ET).

4.26.1 Description (Figure 4-1. Index No. 26). The main landing gear wheels are two-piece aluminum. The items

typically requiring inspection are the aluminum wheel halves, the valve stem boss, the valve stem hole, threaded areas,

and areas around threaded inserts.

4.26.2 Defects. This inspection is used to verify crack indications found visually on the main landing gear wheels.

No cracks are allowed.

4.26.3 Primary Method. Eddy Current.

4-58
TM 1-1520-264-23

Figure 4-25. Main Landing Gear Trailing Arms

4-59
TM 1-1520-264-23

4.26.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.26.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main landing gear wheel assembly shall be removed and

disassembled in accordance with the applicable technical manuals listed in Table 1-1.

4.26.3.3 Access. Not applicable.

4.26.3.4 Preparation of Part. The part shall be thoroughl y cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.26.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos -20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

4-60
TM 1-1520-264-23

4.26.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-26.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.26.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the-probes are changed, steps 4.26.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

4.26.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.26.4 Backup Method. None required.

4.26.5 System Securing. The main landing gear wheel assembly requires assembly and installation in accordance

with the applicable technical manuals listed in Table 1-1.

Figure 4-26. Main Landing Gear Wheels

4-61
TM 1-1520-264-23

4.27 MAIN LANDING GEAR SHOCK STRUT HOUSING, PISTON, AND ROD ENDS (MT).

4.27.1 Description (Figure 4-1. Index No. 27). The main landing gear shock strut assembly attaches to the lower

end of the landing gear trailing arm. The upper end attaches to the fuselage at the landing gear support mount.

4.27.2 Defects. This inspection is used to verify crack indications found visually on the main landing gear shock

strut housing, pistons, rod ends, and locking shear collar. No cracks are allowed.

4.27.3 Primary Method. Magnetic Particle.

4.27.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4.27.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using applicable positions of this procedure. If required, the main landing gear shock struts shall be

removed in accordance with the applicable technical manuals listed in Table 1-1.

4.27.3.3 Access. Access is through the main landing gear shock strut door and ammunition feed mechanism (forward)

fairing (Figure 1-4, Items L/R 135 and L/R 140).

4.27.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.27.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.27.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 4-27.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 4.27.3.8.

f. Repeat steps a. through e. for positions 2, 3, and 4.

4-62
TM 1-1520-264-23

Figure 4-27. Main Landing Gear Shock Strut Housing, Piston, and Rod Ends

4-63
TM 1-1520-264-23

4.27.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.27.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

4.27.4 Backup Method. None required.

4.27.5 System Securing. Clean the main landing gear shock strut rod ends thoroughly to remove all residual

magnetic particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main

landing gear shock strut, if removed, requires installation in accordance with the applicable technical manuals listed in

Table 1-1.

4.28 MAIN LANDING GEAR LOWER-STRUCTURAL SUPPORT (MT).

4.28.1 Description (Figure 4-1. Index No. 28). The main landing gear lower structural support is a boomerangshaped tubular part attached to the cable cutter on one end and a clamp around the trailing arm on the other. There are

two supports, one on each side of the helicopter.

4.28.2 Defects. This inspection is used to verify crack indications found visually on the main landing gear lower

structural support attachment area. No cracks are allowed.

4.28.3 Primary Method. Magnetic Particle.

4.28.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4.28.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using applicable positions of this procedure. If required, the main landing gear lower structural support

shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

4.28.3.3 Access. Not applicable.

4.28.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4-64
TM 1-1520-264-23

4.28.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.28.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 4-28.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 4.28.3.8.

f. Repeat steps a. through e. for position 2.

4.28.3.7 Marking and Recording of Inspection Results. Mark and record inspection results as required by paragraph

1.3.

4.28.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

4.28.4 Backup Method. None required.

4.28.5 System Securing. Clean the main landing gear lower structural support thoroughly to remove all residual

magnetic particle media. Refer to Post Cleaning and Restoration of Part or Area After N DI, paragraph 1.4.16. The main

landing gear lower structural support, if removed, requires installation in accordance with the applicable technical

manuals listed in Table 1-1.

4.29 MAIN LANDING GEAR JACK PAD ADAPTER (MT).

4.29.1. Description (Figure 4-1. Index No. 29). The main landing gear jack pad adapters are found at the inside of

each of the main landing gear.

4.29.2 Defects. This inspection is used to verify crack indications found visually on the main landing gear jack pad

adapter. No cracks are allowed.

4.29.3 Primary Method. Magnetic Particle.

4.29.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

4-65
TM 1-1520-264-23

Figure 4-28. Main Landing Gear Lower Structural Support

4-66
TM 1-1520-264-23

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4.29.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using applicable positions of this procedure. If required, the main landing gear jack pad adapter shall

be removed in accordance with the applicable technical manuals listed in Table 1-1.

4.29.3.3 Access. Not applicable.

4.29.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.29.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.29.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 4-29.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 4.29.3.8.

f. Repeat steps a. through e. for position 2.

4.29.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.29.3.8 Demagnetization: With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

Figure 4-29. Main Landing Gear Jack Pad Adapter

4-67
TM 1-1520-264-23

4.29.4 Backup Method. None required.

4.29.5 System Securing. Clean the main landing gear jack pad adapter thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main landing

gear jack pad, if removed, requires installation in accordance with the applicable technical manuals listed in Table 1-1.

4.30 MAIN LANDING GEAR TRAILING ARM CROSS TUBE (MT).

4.30.1 Description (Figure 4-1. Index No. 30). The main landing gear trailing arm cross tube is the location at which

the upper end of the trailing arm is attached to the helicopter fuselage.

4.30.2 Defects. This inspection is used to verify crack indications found visually on the main landing gear trailing

arm cross tube. No cracks are allowed.

4.30.3 Primary Method. Magnetic Particle.

4.30.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4.30.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main

landing gear trailing arm removed in accordance with the applicable technical manuals listed in Table 1-1.

4.30.3.3 Access. Not applicable.

4.30.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.30.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.30.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 4-30.

4-68
TM 1-1520-264-23

Figure 4-30. Main Landing Gear Trailing Arm Cross Tube

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 4.30.3.8.

f. Repeat steps a. through e. for position 2.

4.30.3.7 Marking and Recording of Inspection Results. Mark and record the i nspection results as required by

paragraph 1.3.

4.30.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

4.30.4 Backup Method. None required.

4.30.5 System Securing. Clean the main landing gear trailing arm cross tube thoroughly to remove all residual

magnetic particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main

landing gear trailing arm requires installation in accordance with the applicable technical manuals listed in Table 1-1.

4-69
TM 1-1520-264-23

4.31 MAIN LANDING GEAR SHOCK STRUT MOUNT SHAFT (MT). (Per TB 1-1520-238-20-81)

4.31.1 Description (Figure 4-1. Index No. 31). The main landing gear shock strut mount shaft projects from the

fuselage and the main landing gear shock strut is attached to it. There is one for each main landing gear.

4.31.2 Defects. This inspection is used to verify crack indications found visually on the main landing gear shock

strut mount shaft. No cracks are allowed.

4.31.3 Primary Method. Magnetic Particle.

4.31.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Hand-held Magnetic Coil

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4.31.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main

landing gear shock strut removed in accordance with the applicable technical manuals listed in Table 1-1.

4.31.3.3 Access. Not applicable.

4.31.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.31.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.31.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The position required for this inspection are illustrated in Figure 4-31.

a. Place coil on part as shown.

b. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

c. Inspect for cracks using the black light.

4.31.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.31.3.8 Demagnetization. Place the coil in the same position used for magnetizing. Press the test switch and

withdraw the coil from the part for a distance of two feet before releasing the switch.

4-70
TM 1-1520-264-23

Figure 4-31. Main Landing Gear Shock Strut Mount Shaft

4-71
TM 1-1520-264-23

4.31.4 Backup Method. None required.

4.31.5 System Securing. Clean the main landing gear mount shaft thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The main landing

gear shock strut requires installation in accordance with the applicable technical manuals listed in Table 1-1.

4.32 TAIL LANDING GEAR FORK (ET).

4.32.1 Description (Figure 4-1. Index No. 32). The tail landing gear fork holds and attaches the tail wheel to the

helicopter by means of a shaft to the tail landing gear trailing arm assembly.

4.32.2 Defects. Defects can occur anywhere on the surface of the tail landing gear fork. No cracks are allowed.

4.32.3 Primary Method. Eddy Current.

4.32.3.1 NDI Equipment and Materials. (Refer to Appendix B )

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.32.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail landing gear fork shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

4.32.3.3 Access. Not applicable.

4.32.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.32.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

4-72
TM 1-1520-264-23

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in

Figure 1-7.)

4.32.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-32.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.32.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 4.32.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

Figure 4-32. Tail Landing Gear Fork

4-73
TM 1-1520-264-23

4.32.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.32.4 Backup Method. None required.

4.32.5 System Securing. The tail landing gear fork, if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

4.33 TAIL WHEEL (ET).

4.33.1 Description (Figure 4-1. Index No. 33). The tail wheel comes either with or without a grease fitting. The

wheels are the same for inspection purposes. The wheel assembly consists of male and female wheel halves.

4.33.2 Defects. This inspection is used to verify crack indications found visually on the tail wheel. No cracks are

allowed.

4.33.3 Primary Method. Eddy Current.

4.33.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.33.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail wheel assembly shall be removed and disassembled in

accordance with the applicable technical manuals listed in Table 1-1.

4.33.3.3 Access. Not applicable.

4.33.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.33.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

4-74
TM 1-1520-264-23

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 

1-7.)

4.33.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-33.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

Figure 4-33. Tail Wheel

4-75
TM 1-1520-264-23

NOTE

Either probe identified in paragraph 4.33.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 4.33.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

4.33.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.33.4 Backup Method. None required.

4.33.5 System Securing. The tail wheel, if removed, requires assembly and installation in accordance with the

applicable technical manuals listed in Table 1-1.

4.34 TAIL LANDING GEAR SHOCK STRUT (MT).

4.34.1 Description (Figure 4-1. Index No. 34). The tail landing gear shock strut is attached to the aft end of the

trailing arm to the aft upper area of the empennage. It absorbs shock generated by the tail landing gear.

4.34.2 Defects. This inspection is used to verify crack indications found visually on the tail landing gear shock strut.

No cracks are allowed.

4.34.3 Primary Method. Magnetic Particle.

4.34.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4.34.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using applicable positions of this procedure. If required, the tail landing gear shock strut shall be

removed in accordance with the applicable technical manuals listed in Table 1-1.

4-76
TM 1-1520-264-23

4.34.3.3 Access. Not applicable.

4.34.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.34.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.34.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 4-34.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media 

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 4.34.3.8.

f. Repeat steps a. through e. for positions 2, 3, and 4.

4.34.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.34.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

4.34.4 Backup Method. None required.

4.34.5 System Securing. Clean the tail landing gear shock strut thoroughly to remove all residual magnetic particle

media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The tail landing gear shock

strut, if removed, requires installation in accordance with the applicable technical manuals listed in Table 1-1.

Figure 4-34. Tail Landing Gear Shock Strut

4-77
TM 1-1520-264-23

4.35 TAIL LANDING GEAR TRAILING ARMS (ET).

4.35.1 Description (Figure 4-1. Index No. 35). The tail landing gear trailing arms are the two lower arms attaching

the tail landing gear to the helicopter.

4.35.2 Defects. Defects can occur anywhere on the surface of the tail landing gear trailing arms. No cracks are

allowed.

4.35.3 Primary Method. Eddy Current.

4.35.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 kHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.35.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail landing gear trailing arms shall be removed in accordance with

the applicable technical manuals listed in Table 1-1.

4.35.3.3 Access. Not applicable.

4.35.3.4 4Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.35.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when 

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 

1-7.)

4-78
TM 1-1520-264-23

4.35.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-35.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal 

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.35.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 4.35.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

4.35.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.35.4 Backup Method. None required.

4.35.5 System Securing. The tail landing gear trailing arms, if removed, require installation in accordance with the

applicable technical manuals listed in Table 1-1.

4.36 TAIL LANDING GEAR ACTUATING CYLINDER ASSEMBLY (ET).

4.36.1 Description (Figure 4-1. Index No. 36). The tail landing gear actuating cylinder allows the tail wheel to lock.

4.36.2 Defects. Defects can occur anywhere on the surface of the tail landing gear actuating cylinder. No cracks are

allowed.

4.36.3 Primary Method. Eddy Current.

4.36.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

4.36.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail landing gear actuating cylinder shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

4-79
TM 1-1520-264-23

Figure 4-35. Tail Landing Gear Trailing Arms

4-80
TM 1-1520-264-23

4.36.3.3 Access. Not applicable.

4.36.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refr to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.36.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when 

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 

1-7.)

4.36.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 4-36.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal 

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 4.36.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 4.36.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

4.36.3.7 4.36.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

4.36.4 Backup Method. None required.

4.36.5 System Securing. The tail landing gear actuating cylinder, if removed, requires installation in accordance with

the applicable technical manuals listed in Table 1-1.

4-81
TM 1-1520-264-23

Figure 4-36. Tail Landing Gear Actuating Cylinder

4.37 BRAKE SYSTEM COMPONENTS (PT).

4.37.1 Description (Figure 4-1'. Index No. 37). The following brake system components are covered by this

procedure: parking brake master cylinder and components; parking brake rotary direct valve and attaching components;

and brake control valves and attaching components. This is a generic procedure to cover all parts requiring inspection.

4.37.2 Defects. This inspection is used to verify crack indications found visually on the brake system components. No

cracks are allowed.

4.37.3 Primary Method. Fluorescent Penetrant.

4.37.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-1-25135

level 3 penetrant materials shall be selected from the approved list in Table 1-8.

4.37.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the brake system

components removed in accordance with the applicable technical manuals listed in Table 1-1.

4.37.3.3 Access. Not applicable.

4.37.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

4.37.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,

paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 4-37.

4-82
TM 1-1520-264-23

Figure 4-37. Brake System Components

4-83
TM 1-1520-264-23

4.37.3.6 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.37.4 Backup Method. None required.

4.37.5 System Securing. Clean the brake system components to remove inspection media. Refer to Post Cleaning

and Restoration of Part or Area After NDI, paragraph 1.4.16. The brake system components require installation in

accordance with the applicable technical manuals listed in Table 1-1.

4.38 GENERAL HELICOPTER ATTACHING HARDWARE (MT).

4.38.1 Description (Figure 4-1 Index No. 38). This inspection is applicable to all attaching hardware contained

throughout the helicopter sections.

4.38.2 Defects. Defects can occur anywhere on the surface of any attaching hardware. No cracks are allowed.

4.38.3 Primary Method. Magnetic Particle.

4.38.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

4.38.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the identified

hardware removed in accordance with the applicable technical manuals listed in Table 1-1.

4.38.3.3 Access. Not applicable.

4.38.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

4.38.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

4.38.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The positions generally required for this inspection are illustrated in Figure 4-38.

4-84
TM 1-1520-264-23

Figure 4-38. General Helicopter Attaching Hardware

4-85
TM 1-1520-264-23

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media 

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

4.38.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

4.38.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

4.38.4 Backup Method. None required.

4.38.5 System Securing. Clean the identified hardware thoroughly to remove all residual magnetic particle media.

Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The identified hardware requires

installation in accordance with the applicable technical manuals listed in Table 1-1.

4-86
TM 1-1520-264-23

SECTION V

ENGINE SYSTEM

5. GENERAL.

5.1 CONTENTS. The engine system inspection items covered in this section are those items of the AH-64A helicopter

gas turbine engine, model T700-GE-701, and components listed in Table 5-1, Engine System Inspection Index.

Corresponding inspection figures and applicable text paragraphs are listed opposite each item. The index number for

each item may be used to locate it in Figure 5-1.

Table 5-1. Engine System Inspection Index

Index Inspection Paragraph Figure

Number Nomenclature Method Number Number

2 Aft Inboard and Aft Lower Engine Mounts ET 5.2 5-2

3 Forward Inboard Engine Mount MT 5.3 5-3

4 Forward Lower Engine Mount MT 5.4 5-4

5 Engine Tubing, Couplings, Air Ducts, Fittings, PT 5.5 5-5

Supports, Brackets, and Clips

6 Air Inlet Assembly ET 5.6 5-6

7 Engine Air Inlet "V" Band Clamp PT 5.7 5-7

8 Starter Flange ET 5.8 5-8

9 Engine Shroud PT 5.9 5-9

10 Engine Load Demand Spindle Bellcrank Support ET 5.10 5-10

11 Engine Components PT 5.11 5-11

5-1
TM 1-1520-264-23

Figure 5-1. Engine System

5-2
TM 1-1520-264-23

5.2 AFT INBOARD AND AFT LOWER ENGINE MOUNTS (ET).

5.2.1 Description (Figure 5-1. Index No. 2). The aft inboard and aft lower mounts are made of titanium and attach

to the diffuser case. This task is applicable to both mounts on both engines.

5.2.2 Defects. This inspection is used to verify crack indications found visually on the engine mounts. No cracks are

allowed.

5.2.3 Primary Method. Eddy Current.

5.2.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched titanium (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

5.2.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the engine mounts shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

5.2.3.3 Access. Access is through the engine door (Figure 1-4, Items R/L N3 and N4).

5.2.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

5.2.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 30°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when 

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 

1-7.)

5-3
TM 1-1520-264-23

5.2.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 5-2.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal 

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 5.2.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 5.2.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

5.2.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.2.4 Backup Method. None required.

5.2.5 System Securing. The engine mounts, if removed, require installation in accordance with the applicable

technical manuals listed in Table 1-1.

5.3 FORWARD INBOARD ENGINE MOUNT (MT).

5.3.1 Description (Figure 5-1. Index No. 3). The forward inboard engine mount is attached to the forward inboard

portion of the engine main frame.

5.3.2 Defects. This inspection is used to verify crack indications found visually. No cracks are allowed.

5.3.3 Primary Method. Magnetic Particle.

5.3.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

5.3.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the engine mount

removed in accordance with the applicable technical manuals listed in Table 1-1.

5-4
TM 1-1520-264-23

Figure 5-2. Aft Inboard and Aft Lower Engine Mounts

5-5
TM 1-1520-264-23

5.3.3.3 Access. Remove engine.

5.3.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

5.3.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

5.3.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 5-3.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media 

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 5.3.3.8.

f. Repeat steps a. through e. for positions 2 and 3.

5.3.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.3.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

5.3.4 Backup Method. None required.

5.3.5 System Securing. Clean the engine mount thoroughly to remove all residual magnetic particle media. Refer to

Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The engine mount requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

5.4 FORWARD LOWER ENGINE MOUNT (MT).

5.4.1 Description (Figure 5-1. Index No. 4). The forward lower engine mount is attached to the lower forward

portion of the engine main frame. This task is applicable to mounts on both engines.

5.4.2 Defects. This inspection is used to verify crack indications found visually. No cracks are allowed.

5.4.3 Primary Method. Magnetic Particle.

5.4.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

5-6
TM 1-1520-264-23

NDI_AH-64_FS_3

Figure 5-3. Forward Inboard Engine Mount

5-7
TM 1-1520-264-23

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

5.4.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the engine mount

removed in accordance with the applicable technical manuals listed in Table 1-1.

5.4.3.3 Access. Remove engine.

5.4.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

5.4.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

5.4.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. Positions required for this inspection are illustrated in Figure 5-4.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle. media at the same time. Remove the media 

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 5.4.3.8.

f. Repeat steps a. through e. for position 2.

5.4.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.4.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

5.4.4 Backup Method. None required.

5.4.5 System Securing. Clean the engine mount thoroughly to remove all residual magnetic particle media. Refer to

Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The engine mount requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

5.5 ENGINE TUBING, COUPLINGS, AIR DUCTS, FITTINGS, SUPPORTS, BRACKETS, AND CLIPS (PT).

5.5.1 Description (Figure 5-1. Index No. 5). This task is for all metallic, unpainted engine tubing, couplings, air

ducts, related fittings, supports, brackets, and bracket clips.

5.5.2 Defects. This inspection is used to verify crack indications found visually. No cracks are allowed.

5-8
TM 1-1520-264-23

Figure 5-4. Forward Lower Engine Mount

5-9
TM 1-1520-264-23

5.5.3 Primary Method. Fluorescent Penetrant.

5.5.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-I-25135

level 3 penetrant materials shall be selected from the approved list in Table 1-8.

5.5.3.2 Preparation of Helicopter. The helicopter shall be prepared for saf e ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the part(s) shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

5.5.3.3 Access. Refer to Figure 1-4 as applicable.

5.5.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

5.5.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,

paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 5-5.

5.5.3.6 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.5.4 Backup Method. None required.

5.5.5 System Securing. Clean the part(s) to remove inspection media. Refer to Post Cleaning and Restoration of

Part or Area After NDI, paragraph 1.4.16. The part(s), if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

5.6 AIR INLET ASSEMBLY (ET).

5.6.1 Description (Figure 5-1. Index No. 6). The aluminum air inlet assembly is at the front of the engine through

which air is directed into the engine.

5.6.2 Defects. This inspection is used to verify crack indications found visually on the air inlet. No cracks are

allowed.

5.6.3 Primary Method. Eddy Current.

5.6.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

5.6.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the air inlet assembly shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

5-10
TM 1-1520-264-23

Figure 5-5. Engine Tubing, Couplings, Air Ducts, Fittings, Supports, Brackets, and ;Clips

5-11
TM 1-1520-264-23

5.6.3.3 Access. Not applicable.

5.6.3.4 Preparation of Part. The part shall be thoroughl y cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

5.6.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when 

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 

1-7.)

5.6.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 5-6.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal 

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 5.6.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 5.6.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

5.6.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.6.4 Backup Method. None required.

5.6.5 System Securing. The air inlet assembly, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

5-12
TM 1-1520-264-23

Figure 5-6. Air Inlet Assembly

5.7 ENGINE AIR INLET "V" BAND CLAMP (PT).

5.7.1 Description (Figure 5-1. Index No. 7). The air inlet flange is integral to air inlet. The engine (compressor

case) flange is integral to the compressor case. The "V" band clamp holds the air inlet to the compressor case.

5.7.2 Defects. This inspection is used to verify crack indications found visually in the "V" band clamp. No cracks are

allowed.

5.7.3 Primary Method. Fluorescent Penetrant.

5.7.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-I-25135

level 3 penetrant materials shall be selected from the approved list in Table 1-8.

5.7.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A part ial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.),may be performed on all exposed surfaces of

the installed part using this procedure. If required, the flanges shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

5.7.3.3 Access. Access is through access doors (Figure 1-4, Items LN1 or RN1).

5.7.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

5.7.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,

paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 5-7.

5-13
TM 1-1520-264-23

Figure 5-7. Engine Air Inlet “V” Band Clamp

5.7.3.6 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.7.4 Backup Method. None required.

5.7.5 System Securing. Clean the "V" band clamp to remove inspection media. Refer to Post Cleaning and

Restoration of Part or Area After NDI, paragraph 1.4.16. The "V" band, if removed, requires installation in accordance

with the applicable technical manuals listed in Table 1-1.

5.8 STARTER FLANGE (ET).

5.8.1 Description (Figure 5-1. Index No. 8). The air starter is located on the right upper side of the engine and is

mounted to the engine accessory drive case. It uses compressed air from the APU to turn the engine.

5.8.2 Defects. This inspection is used to verify crack indications found visually on the starter flange. No cracks are

allowed.

5.8.3 Primary Method. Eddy Current.

5-14
TM 1-1520-264-23

5.8.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

5.8.3.2 Preparation of Helicopter. The helicopter shall-be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the starter flange shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

5.8.3.3 Access. Access is through engine access doors (Figure 1-4, Items LN1 or RN1).

5.8.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

5.8.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when 

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 

1-7.)

5.8.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 5-8.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizo ntal 

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

5-15
TM 1-1520-264-23

Figure 5-8. Starter Flange

NOTE

Either probe identified in paragraph 5.8.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 5.8.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

5.8.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.8.4 Backup Method. None required.

5.8.5 System Securing. The starter flange, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

5.9 ENGINE SHROUD (PT).

5.9.1 Description (Figure 5-1. Index No. 9). The engine shroud is mounted on top of the engine.

5.9.2 Defects. This inspection is used to verify crack indications found visually. No cracks are

allowed.

5.9.3 Primary Method. Fluorescent Penetrant.

5-16
TM 1-1520-264-23

5.9.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-1-25135

level 3 penetrant materials shall be selected from the approved list in Table 1-8.

5.9.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the shroud shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

5.9.3.3 Access. Access is through access doors (Figure 1-4, Items LN1 or RN1).

5.9.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

5.9.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,

paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 5-9.

5.9.3.6 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.9.4 Backup Method. None required.

5.9.5 System Securing. Clean the shroud to remove inspection media. Refer to Post Cleaning and Restoration of

Part or Area After NDI, paragraph 1.4.16. The shroud, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

Figure 5-9. Engine Shroud

5-17
TM 1-1520-264-23

5.10ENGINE LOAD DEMAND SPINDLE BELLCRANK SUPPORT (ET).

5.10.1 Description (Figure 5-1. Index No. 10). This support is located on the transmission bay dock, just forward of

the transmission. It is the point at which three systems join. It ties the engines (torque sensing) to the flight controls

(pilot/CPG's collectives) and is mounted in the main part of the airframe.

5.10.2 Defects. This inspection is used to verify crack indications found visually on the support. No cracks are

allowed.

5.10.3 Primary Method. Eddy Current.

5.10.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

5.10.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the support shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

5.10.3.3 Access. Access is through access panels (Figure 1-4, Items L200 and R200).

5.10.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

5.10.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when 

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 

1-7.)

5-18
TM 1-1520-264-23

5.10.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 5-10.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 5.10.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 5.10.3.5 b. (1), (2), and (3) shall be repeated each time a change is made.

5.10.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.10.4 Backup Method. None required.

5.10.5 System Securing. The support, if removed, requires installation in accordance with the applicable technical

manuals listed in Table 1-1.

Figure 5-10. Engine Load Demand Spindle Bellcrank Support

5-19
TM 1-1520-264-23

5.11 ENGINE COMPONENTS (PT).

5.11.1 Description (Figure 5-1. Index No. 11). The engine components to be inspected are the power turbine,

combustion chamber, compression housing, exhaust nozzles, and IR suppressors.

5.11.2 Defects. This inspection is to: (1) verify cracks found by visual inspection, (2) locate exact end of cracks found to

facilitate stop drilling of the crack, and (3) to make sure no cracks are present after repairs.

5.11.3 Primary Method. Fluorescent Penetrant.

5.11.3.1 NDI Equipment and Materials. (Refer to Appendix B.) Inspection equipment is listed in Table 1-7. MIL-1-25135

level 3 penetrant materials shall be selected from the approved list in Table 1-8.

5.11.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the engine shall be removed in accordance with the applicable

technical manuals listed in Table 1-1.

5.11.3.3 Access. Access is through access door (Figure 1-4, Items LN1 or RN1).

5.11.3.4 Preparation of Part. Refer to Preparation of Part or Area for NDI, paragraph 1.4.4.

5.11.3.5 Inspection Procedure. Perform fluorescent penetrant inspection. Refer to Fluorescent Penetrant Method,

paragraph 1.4.7 and Table 1-5. Inspect area of concern. See Figure 5-11.

5.11.3.6 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

5.11.4 Backup Method. None required.

5.11.5 System Securing. Clean the inspected area to remove inspection media. Refer to Post Cleaning and Restoration

of Part or Area After NDI, paragraph 1.4.16. The engine, if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

5-20
TM 1-1520-264-23

Figure 5-11. Engine Components

5-21/(5-22 blank)
TM 1-1520-264-23

SECTION VI

FLIGHT CONTROL SYSTEM

6. GENERAL.

6.1 CONTENTS. The flight control system inspection items covered in this section are those items of the AH-64A

helicopter flight control and related hydraulic systems. The parts and components are listed in the Flight Control System

Inspection Index (Table 6-1). Corresponding inspection figures and applicable text paragraphs are listed opposite each

item. The index number for each item may be used to locate it in Figure 6-1.

Table 6-1. Flight Control System Inspection Index

Index Inspection Paragraph Figure

Number Nomenclature Method Number Number

2 Flight Control Bellcranks ET 6.2 6-2

3 Main Rotor Swashplate Shoulder Pin Mating ET 6.3 6-3

Bores

*4 Main Rotor Link Barrels MT 6.4 6-4

5 Main Rotor Scissors Upper Arm ET 6.5 6-5

6 Main Rotor Scissors Lower Arm ET 6.6 6-6

7 Pilot/CPG Collective Stick Tube ET 6.7 6-7

8 Pilot/CPG Collective Stick Rotor Housing ET 6.8 6-8

9 Pilot Collective Stick Cylinder ET 6.9 6-9

*10 Flight Control Rods, Connecting Links, Rod ET 6.10 6-10

Ends, Clevises, Levers, and Attaching Parts

11 Pilot Collective Stick Support Assembly ET 6.11 6-11

12 CPG Collective Stick Support Assembly ET 6.12 6-12

13 Pilot Cyclic Stick ET 6.13 6-13

14 Lateral Feel Spring Cartridge ET 6.14 6-14

15 Pilot Cyclic Stick Housing and Support Assembly ET 6.15 6-15

*16 CPG Cyclic Stick Forward and Aft Links ET 6.16 6-16

*17 CPG Cyclic Stick Remote Control Lever ET 6.17 6-17

18 CPG Cyclic Stick Fitting Assembly ET 6.18 6-18

*19 Ferrous Flight Control System Push-Pull Rods MT 6.19 6-19

*20 Nonferrous Flight Control System Push-Pull ET 6.20 6-20

Rods

*21 CPG to Pilot Longitudinal F.S. 82.80 Control ET 6.21 6-21

Bracket

6-1
TM 1-1520-264-23

Table 6-1. Flight Control System Inspection Index - Continued

Index Inspection Paragraph Figure

Number Nomenclature Method Number Number

*22 CPG to Pilot Collective F.S. 118.50 Bellcrank ET 6.22 6-22

23 CPG Directional Shear Pin Activated Decoupler ET 6.23 6-23

(SPAD) Arms

*24 Directional F.S. 121.40 Bellcrank ET 6.24 6-24

*25 Directional F.S. 121.40 Bellcrank Bracket ET 6.25 6-25

26 Pilot Directional Shear Pin Activated Decoupler ET 6.26 6-26

(SPAD) Transducer, Arm

*27 Pilot Directional Shear Pin Activated Decoupler ET 6.27 6-27

(SPAD) Remote Control Lever

*28 Pilot Directional Shear Pin Activated Decoupler ET 6.28 6-28

(SPAD) Bellcranks

*29 Directional F.S. 156.07 Bellcrank ET 6.29 6-29

*30 Directional F.S. 159.98 Bellcrank and Bracket ET 6.30 6-30

31 Directional F.S. 164.33 Bellcrank Bracket and ET 6.31 6-31

Attaching Area on Deck

32 Pilot Longitudinal Shear Pin Activated Decoupler ET 6.32 6-32

(SPAD) Outer and Inner Lever

33 Pilot/CPG Directional Control Pedal Release ET 6.33 6-33

Handle

34 Pilot/CPG Directional Control Pedal Release MT 6.34 6-34

Shaft

35 Pilot/CPG Directional Control Pedal Release Nuts MT 6.35 6-35

36 Directional F.S. 199.25 Tail Rotor Fitting ET 6.36 6-36

37 Directional F.S. 275 Rotor Control Bracket ET 6.37 6-37

*38 Directional F.S. 348 Bellcrank ET 6.38 6-38

39 Directional F.S. 348 Tail Rotor Bracket ET 6.39 6-39

*40 Tail Rotor Swashplate Control Bellcrank MT 6.40 6-40

*41 Tail Rotor Drive Links ET 6.41 6-41

42 Exterior Surfaces of All Ferrous Hydraulic MT 6.42 6-42

Components (Servocylinders, Actuators,

Reservoirs, etc.)

NOTE: *Indicates Flight Safety Part.

6-2
TM 1-1520-264-23

Figure 6-1. Flight Control System (Sheet 1 of 2)

6-3
TM 1-1520-264-23

Figure 6-1. Flight Control System (Sheet 2 of 2)

6-4
TM 1-1520-264-23

6.2 FLIGHT CONTROL BELLCRANKS (ET).

6.2.1 Description (Figure 6-1. Index No. 2). This inspection is applicable to all non-ferromagnetic bellcranks contained

within the flight control system.

6.2.2 Defects. The primary purpose of this inspection is for: (1) confirmation of crack indications identified by visual

inspections; (2) verification that scratches and gouges do not conceal cracks; and (3) ensure no cracks are present after

blend out procedures.

6.2.3 Primary Method. Eddy Current.

6.2.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.2.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed bellcranks using this procedure. If required, the bellcrank(s) shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

6.2.3.3 Access. Accessibility of the bellcranks varies considerably. Refer to Figure 1-4 and Table 1-2 to locate

applicable access provisions.

6.2.3.4 Preparation of Part. The part(s) shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.2.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11 .

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe 

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-5
TM 1-1520-264-23

6.2.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-2.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.2.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 6.2.3.5 b. (1), (2), and (3) shall be repeated each

time a charge is made.

6.2.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.2.4 Backup Method. None required.

6.2.5 System Securing. The bellcrank(s), if removed, require(s) installation in accordance with the applicable technical

manuals listed in Table 1-1.

6.3 MAIN ROTOR SWASHPLATE SHOULDER PIN MATING BORES (ET).

6.3.1 Description (Figure 6-1. Index No. 3). The task is typical for both the load bearing scissors shoulder pin and the

secondary scissors shoulder pin bores. The bores are located in the swashplate itself and mate with the removed

shoulder pins.

6.3.2 Defects. This inspection is used to verify crack indications found visually on the main rotor swashplate shoulder

pin mating bore and the secondary scissors shoulder pin bore. No cracks are allowed.

6.3.3 Primary Method. Eddy Current.

6.3.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.3.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the main rotor

swashplate shoulder pin removed in accordance with the applicable technical manuals listed in Table 1-1.

6.3.3.3 Access. Not applicable.

6.3.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6-6
TM 1-1520-264-23

Figure 6-2. Flight Control Bellcranks

6-7
TM 1-1520-264-23

6.3.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when 

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in 

Figure 1-7.)

6.3.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-3.

Figure 6-3. Main Rotor Swashplate Shoulder Pin Mating Bores

6-8
TM 1-1520-264-23

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.3.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 6.3.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

6.3.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.3.4 Backup Method. Not applicable.

6.3.5 System Securing. The main rotor swashplate shoulder pin requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

6.4 MAIN ROTOR LINK BARRELS (MT).

6.4.1 Description (Figure 6-1. Index No. 4). The main rotor pitch link barrel is the major center part of the main rotor

pitch link into which the two rod's ends mount.

6.4.2 Defects. Defects can occur anywhere on the surface of the part. No cracks are allowed.

6.4.3 Primary Method. Magnetic Particle.

6.4.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

6.4.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the pitch link

removed and disassembled in accordance with the applicable technical manuals listed in Table 1-1.

6.4.3.3 Access. Not applicable.

6-9
TM 1-1520-264-23

6.4.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.4.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

6.4.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of possible

cracks. The position required for this inspection is illustrated in Figure 6-4.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five 

seconds.

d. Inspect for cracks using the black light.

6.4.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.4.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same position

used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet before

releasing the switch.

6.4.4 Backup Method. Fluorescent Penetrant, refer to paragraph 1.4.7.

6.4.5 System Securing. Clean the link barrel thoroughly to remove all residual magnetic particle media. Refer to Post

Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The pitch link requires assembly and installation

in accordance with the applicable technical manuals listed in Table 1-1.

Figure 6-4. Main Rotor Link Barrels

6-10
TM 1-1520-264-23

6.5 MAIN ROTOR SCISSORS UPPER ARM (ET).

6.5.1 Description (Figure 6-1. Index No. 5). The main rotor scissors upper arm is the upper portion of the scissors

assembly. The task is typical for both load bearing and secondary main rotor scissors.

6.5.2 Defects. This inspection is used to verify crack indications found visually on the main rotor scissors upper arm.

No cracks are allowed.

6.5.3 Primary Method. Eddy Current.

6.5.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.5.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the main rotor scissors upper arm shall be removed in accordance

with the applicable technical manuals listed in Table 1-1.

6.5.3.3 Access. Not applicable.

6.5.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.5.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe 

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-11
TM 1-1520-264-23

6.5.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-5.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.5.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 6.5.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

6.5.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.5.4 Backup Method. None required.

6.5.5 System Securing. The main rotor scissors upper arm, if removed, requires installation in accordance with

applicable technical manuals listed in Table 1-1.

Figure 6-5. Main Rotor Scissors Upper Arm

6-12
TM 1-1520-264-23

6.6 MAIN ROTOR SCISSORS LOWER ARM (ET).

6.6.1 Description (Figure 6-1. Index No. 6). The task is typical for both load bearing and secondary main rotor scissors.

The scissors are attached to, and mounted underneath, the swashplate.

6.6.2 Defects. This inspection is used to verify crack indications found visually on the main rotor scissors lower arm. No

cracks are allowed.

6.6.3 Primary Method. Eddy Current.

6.6.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.6.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on. all exposed surfaces of

the installed part using this procedure. If required, the main rotor scissors lower arm shall be removed in accordance

with the applicable technical manuals listed in Table 1-1.

6.6.3.3 Access. Not applicable.

6.6.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.6.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e 11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 560

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when 

probe is passed over 0.040-inch notch in test block. (See the standard instrument display shown in 

Figure 1-7.)

6-13
TM 1-1520-264-23

6.6.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-6.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.6.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 6.6.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

6.6.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.6.4 Backup Method. None required.

6.6.5 System Securing. The main rotor scissors lower arm requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

Figure 6-6. Main Rotor Scissors Lower Arm

6-14
TM 1-1520-264-23

6.7 PILOT/CPG COLLECTIVE STICK TUBE (ET).

6.7.1 Description (Figure 6-1. Index No. 7). The task is typical for either the pilot or CPG collective stick tubes. The

pilot/CPG collective stick tubes are a part of the collective stick grips.

6.7.2 Defects. This inspection is used to verify crack indications found visually on the pilot/CPG collective stick tube.

No cracks are allowed.

6.7.3 Primary Method. Eddy Current.

6.7.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.7.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the pilot/CPG collective stick tube shall be removed in accordance

with the applicable technical manuals listed in Table 1-1.

6.7.3.3 Access. Access is through the pilot/CPG crew stations.

6.7.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.7.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe 

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-15
TM 1-1520-264-23

6.7.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-7.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.7.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 6.7.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

6.7.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.7.4 Backup Method. None required.

6.7.5 System Securing. The pilot/CPG collective stick tube requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

Figure 6-7. Pilot/CPG Collective Stick Tube

6-16
TM 1-1520-264-23

6.8 PILOT/CPG COLLECTIVE STICK ROTOR HOUSING (ET).

6.8.1 Description (Figure 6-1. Index No. 8). The task is typical for either the pilot or CPG collective rotor housing. The

pilot/CPG collective rotor housings are a part of the collective stick grips.

6.8.2 Defects. This inspection is used to verify crack indications found visually on the pilot/CPG collective stick rotor

housing. No cracks are allowed.

6.8.3 Primary Method. Eddy Current.

6.8.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.8.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the pilot/CPG collective stick rotor housing shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

6.8.3.3 Access. Access is through the pilot/CPG crew stations.

6.8.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.8.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe 

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-17
TM 1-1520-264-23

6.8.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-8.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.8.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 6.8.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

6.8.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.8.4 Backup Method. None required.

6.8.5 System Securing. The pilot/CPG collective stick rotor housing requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

Figure 6-8. Pilot/CPG Collective Stick Rotor Housing

6-18
TM 1-1520-264-23

6.9 PILOT COLLECTIVE STICK CYLINDER (ET).

6.9.1 Description (Figure 6-1. Index No. 9). The pilot collective stick cylinder attaches between the collective arm and

the airframe bracket. The cylinder attenuates vibrations/feed-back to the pilot collective stick assembly.

6.9.2 Defects. This inspection is used to verify crack indications found visually on the pilot collective stick cylinder. No

cracks are allowed.

6.9.3 Primary Method. Eddy Current.

6.9.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.9.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the pilot collective

stick cylinder removed in accordance with the applicable technical manuals listed in Table 1-1.

6.9.3.3 Access. Not applicable.

6.9.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.9.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-19
TM 1-1520-264-23

6.9.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-9.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.9.3.1 may be used depending primarily on the ease of accessibility

and user friendliness. If the probes are changed, steps 6.9.3.5 b. (1), (2), and (3) shall be repeated each

time a change is made.

6.9.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.9.4 Backup Method. None required.

6.9.5 System Securing. The pilot collective stick cylinder requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

Figure 6-9. Pilot Collective Stick Cylinder

6-20
TM 1-1520-264-23

6.10 FLIGHT CONTROL RODS, CONNECTING LINKS, ROD ENDS, CLEVISES, LEVERS, AND

ATTACHING PARTS (ET).

6.10.1 Description (Figure 6-1, Index No. 10). Flight control rods, connecting links, rod ends, clevises, levers, and

attaching parts are found in various locations in the helicopter flight controls. This is a generic inspection for all such

parts.

6.10.2 Defects. This inspection is used to verify crack indications found visually on the flight control rods, connecting

links, rod ends, devises, levers, and attaching parts. No cracks are allowed.

6.10.3 Primary Method. Eddy Current.

6.10.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.10.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the flight control rods, connecting links, rod ends, clevises, levers, and

attaching parts shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

6.10.3.3 Access. Accessibility of the flight control rods, connecting links, rod ends, clevises, levers, and attaching parts

varies considerably. Refer to Figure 1-4 and Table 1-2 to locate applicable access provisions.

6.10.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.10.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

6-21
TM 1-1520-264-23

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.10.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-10.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.10.3.1 may be used depending primarily on the ease of

accessibility and user friendliness. If the probes are changed, steps 6.10.3.5 b. (1), (2), and (3) shall be

repeated each time a change is made.

6.10.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.10.4 Backup Method. None required.

6.10.5 System Securing. The flight control rods, connecting links, rod ends, devises, levers, and attaching parts, if

removed, require installation in accordance with the applicable technical manuals listed in Table 1-1.

6.11 PILOT COLLECTIVE STICK SUPPORT ASSEMBLY (ET).

6.11.1 Description (Figure 6-1, Index No. 11). The pilot collective stick support assembly provides the supporting

structure to mount the pilot's collective stick to the airframe. Inspect the support itself, the output arm, and the input arm.

6.11.2 Defects. This inspection is used to verify crack indications found visually on the pilot collective stick support

assembly. No cracks are allowed.

6.11.3 Primary Method. Eddy Current.

6.11.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6-22
TM 1-1520-264-23

Figure 6-10. Flight Control Rods, Connecting Links,

Rod Ends, Clevises, Levers, and Attaching Parts

6-23
TM 1-1520-264-23

6.11.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the pilot

collective stick support assembly removed in accordance with the applicable technical manuals listed in Table 1-1.

6.11.3.3 Access. Not applicable

6.11.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.11.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot -56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when. probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.11.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-11.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.11.3.1 may be used depending primarily on the ease of

accessibility and user friendliness. If the probes are changed, steps 6.11.3.5 b. (1), (2), and (3) shall be

repeated each time a change is made.

6.11.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.11.4 Backup Method. None required.

6.11.5 System Securing. The pilot collective stick support assembly requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

6-24
TM 1-1520-264-23

Figure 6-11. Pilot Collective Stick Support Assembly

6.12 CPG COLLECTIVE STICK SUPPORT ASSEMBLY (ET).

6.12.1 Description (Figure 6-1, Index No. 12). The CPG collective stick support assembly mounts the CPG's collective

stick to the airframe. Check the drive arm, the output arm, the input arm, and the base.

6.12.2 Defects. This inspection is used to verify crack indications found visually on the CPG collective stick support

assembly. No cracks are allowed.

6.12.3 Primary Method. Eddy Current.

6.12.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6-25
TM 1-1520-264-23

6.12.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the CPG

collective stick support assembly removed in accordance with the applicable technical manuals listed in Table 1-1.

6.12.3.3 Access. Not applicable.

6.12.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.12.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 -200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos. - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe 

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.12.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-12.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.12.3.1 may be used depending primarily on the ease of

accessibility and user friendliness. If the probes are changed, steps 6.12.3.5 b. (1), (2), and (3) shall be

repeated each time a change is made.

6.12.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.12.4 Backup Method. None required.

6.12.5 System Securing. The CPG collective stick support assembly requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

6-26
TM 1-1520-264-23

Figure 6-12. CPG Collective Stick Support Assembly

6.13 PILOT CYCLIC STICK (ET).

6.13.1 Description (Figure 6-1. Index No. 13). The pilot cyclic stick is found in the cockpit at the pilot's

station. Inspect the stick and attaching parts.

6.13.2 Defects. This inspection is used to verify crack indications found visually on the pilot cyclic stick. No cracks are

allowed.

6.13.3 Primary Method. Eddy Current.

6.13.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6-27
TM 1-1520-264-23

6.13.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the pilot cyclic stick shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

6.13.3.3 Access. Access is through the pilot crew station.

6.13.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.13.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe 

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.13.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-13.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.13.3.1 may be used depending primarily on the ease of

accessibility and user friendliness. If the probes are changed, steps 6.13.3.5 b. (1), (2), and (3) shall be

repeated each time a change is made.

6.13.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by paragraph

1.3.

6.13.4 Backup Method. None required.

6.13.5 System Securing. The pilot cyclic stick, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

6-28
TM 1-1520-264-23

Figure 6-13. Pilot Cyclic Stick

6.14 LATERAL FEEL SPRING CARTRIDGE (ET).

6.14.1 Description (Figure 6-1. Index No. 14). The lateral feel spring cartridge is found at the base of the pilot's cyclic

stick attached to the magnetic brake arm.

6.14.2 Defects. This inspection is used to verify crack indications found visually on the lateral feel spring cartridge. No

cracks are allowed.

6.14.3 Primary Method. Eddy Current.

6.14.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6-29
TM 1-1520-264-23

6.14.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the lateral feel

spring cartridge removed in accordance with the applicable technical manuals listed in Table 1-1.

6.14.3.3 Access. Not applicable.

6.14.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.14.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19ell.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.14.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-14.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.14.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 6.14.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

6.14.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.14.4 Backup Method. None required.

6.14.5 System Securing. The lateral feel spring cartridge, if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

6-30
TM 1-1520-264-23

Figure 6-14. Lateral Feel Spring Cartridge

6.15 PILOT CYCLIC STICK HOUSING AND SUPPORT ASSEMBLY (ET).

6.15.1 Description (Figure 6-1. Index No. 15). The pilot cyclic stick housing and support assembly are found at the base

of the pilot's cyclic stick flight control. Check the support and housing.

6.15.2 Defects. This inspection is used to verify crack indications found visually on the pilot cyclic stick, housing and

support assembly. No cracks are allowed.

6.15.3 Primary Method. Eddy Current.

6.15.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6-31
TM 1-1520-264-23

6.15.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the pilot cyclic

stick housing and support-assembly removed in accordance with the applicable technical manuals listed in Table 1-1.

6.15.3.3 Access. Not applicable.

6.15.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.15.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e1.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -O

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.15.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-15.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.15.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.15.3.5 b. (1), (2), and (3) shall be repeated each time a change is made.

6.15.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.15.4 Backup Method. None required.

6.15.5 System Securing. The pilot cyclic stick housing and support assembly require installation in accordance with the

applicable technical manuals listed in Table 1-1.

6-32
TM 1-1520-264-23

Figure 6-15. Pilot Cyclic Stick Housing and Support Assembly

6-33
TM 1-1520-264-23

6.16 CPG CYCLIC STICK FORWARD AND AFT LINKS (ET).

6.16.1 Description (Figure 6-1. Index No. 16). The CPG cyclic stick forward and aft links are found in the CPG's cyclic

control stick assembly at the forward lower portion and the aft mid-portion,, respectively.

6.16.2 Defects. This inspection is used to verify crack indications found visually on the CPG cyclic stick forward and aft

links. No cracks are allowed.

6.16.3 Primary Method. Eddy Current.

6.16.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.16.3.2 Preparation of Helicopter. The. helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the CPG cyclic stick forward and aft links shall be removed

in accordance with the applicable technical manuals listed in Table 1-1.

6.16.3.3 Access. Access is from the CPG station.

6.16.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.16.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

HPF -0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-34
TM 1-1520-264-23

6.16.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-16.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.16.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 6.16.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

6.16.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.16.4 Backup Method. None required.

6.16.5 System Securing. The CPG cyclic stick forward and aft links, if removed, require installation in accordance with

the applicable technical manuals listed in Table 1-1.

6.17 CPG CYCLIC STICK REMOTE CONTROL LEVER (ET).

6.17.1 Description (Figure 6-1. Index No. 17). The CPG cyclic stick remote control lever is located on the CPG's cyclic

stick assembly, on the left side at the lower, mid portion.

6.17.2 Defects. This inspection is used to verify crack indications found visually on the CPG cyclic stick remote control

lever. No cracks are allowed.

6.17.3 Primary Method. Eddy Current.

6.17.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.17.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the CPG cyclic stick remote control lever shall be removed

in accordance with the applicable technical manuals listed in Table 1-1.

6-35
TM 1-1520-264-23

Figure 6-16. CPG Cyclic Stick Forward and Aft Links

6-36
TM 1-1520-264-23

6.17.3.3 Access. Access is from the CPG station.

6.17.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.17.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - O

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.17.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-17.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.17.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 6.17.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

6.17.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.17.4 Backup Method. None required.

6.17.5 System Securing. The CPG cyclic stick remote control lever, if removed, requires installation in accordance with

the applicable technical manuals listed in Table 1-1.

6-37
TM 1-1520-264-23

Figure 6-17. CPG Cyclic Stick Remote Control Lever

6.18 CPG CYCLIC STICK FITTING ASSEMBLY (ET).

6.18.1 Description (Figure 6-1. Index No. 18). The CPG cyclic stick fitting assembly is at the base of the cyclic stick and

connects the cyclic stick to the cyclic adjust lock assembly. Inspect the fitting assembly, the cyclic adjust lock assembly,

and the CPG cyclic stick.

6.18.2 Defects. This inspection is used to verify crack indications found visually on the CPG cyclic stick fitting

assembly. No cracks are allowed.

6.18.3 Primary Method. Eddy Current.

6.18.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6-38
TM 1-1520-264-23

6.18.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the CPG cyclic stick fitting assembly shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

6.18.3.3 Access. Access is through the CPG station.

6.18.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.18.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF -.0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.18.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-18.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.18.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 6.18.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

6.18.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.18.4 Backup Method. None required.

6.18.5 System Securing. The CPG cyclic stick fitting assembly, if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

6-39
TM 1-1520-264-23

Figure 6-18. CPG Cyclic Stick Fitting Assembly

6-40
TM 1-1520-264-23

6.19 FERROUS FLIGHT CONTROL SYSTEM PUSH-PULL RODS (MT).

6.19.1 Description (Figure 6-1. Index No. 19). This is a generic inspection pertaining to ferrous flight control system

push-pull rods throughout the helicopter.

6.19.2 Defects. This inspection is used to verify crack indications found visually on the flight control system push-pull

rods. No cracks are allowed.

6.19.3 Primary Method. Magnetic Particle.

6.19.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

6.19.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed parts using applicable positions of this procedure. If required, the flight control system push-pull

rods shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

6.19.3.3 Access. Refer to Figure 1-4 and Table 1-2, as applicable.

6.19.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.19.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

6.19.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 6-19.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the media

momentarily before removing the current. Current should be applied for no more than five seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 6.19.3.8.

f. Repeat steps a. through e. for other positions, as required.

6-41
TM 1-1520-264-23

Figure 6-19. Ferrous Flight Control System Push-Pull Rods

6-42
TM 1-1520-264-23

6.19.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.19.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

6.19.4 Backup Method. None required.

6.19.5 System Securing. Clean the flight control system push-pull rods thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The flight control

system push-pull rods, if removed, require installation in accordance with the applicable technical manuals listed in Table

1-1.

6.20 NONFERROUS FLIGHT CONTROL SYSTEM P USH-PULL RODS (ET).

6.20.1 Description (Figure 6-1. Index No. 20). This is a generic inspection pertaining to nonferrous flight control system

push-pull rods throughout the helicopter.

6.20.2 Defects. This inspection is used to verify crack indications found visually on the flight control system push-pull

rods. No cracks are allowed.

6.20.3 Primary Method. Eddy Current.

6.20.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.20.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the flight control system push-pull rods shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

6.20.3.3 Access. Refer to Figure 1-4, Table 1-2, as applicable.

6.20.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6-43
TM 1-1520-264-23

6.20.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos -20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.20.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-20.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal

lift-off.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.20.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 6.20.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

6.20.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.20.4 Backup Method. None required.

6.20.5 System Securing. The flight control system push-pull rods, if removed, require installation in accordance with the

applicable technical manuals listed in Table 1-1.

6-44
TM 1-1520-264-23

Figure 6-20. Nonferrous Flight Control System Push-Pull Rods

6-45
TM 1-1520-264-23

6.21 CPG TO PILOT LONGITUDINAL F.S. 82.80 CONTROL BRACKET (ET).

6.21.1 Description (Figure 6-1. Index No. 21). The CPG to pilot longitudinal F.S. 82.80 control bracket holds the

bellcrank connecting the push-pull rods from the CPG to the pilot's longitudinal controls.

6.21.2 Defects. This inspection is used to verify crack indications found visually on the CPG to pilot longitudinal F.S.

82.80 control bracket. No cracks are allowed.

6.21.3 Primary Method. Eddy Current.

6.21.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.21.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using this procedure. If required, the CPG to pilot longitudinal F.S. 82.80 control bracket

shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

6.21.3.3 Access. Access is through the FAB and controls, and flight controls covers (Figure 1-4, Items B80R and

B85R).

6.21.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.21.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-46
TM 1-1520-264-23

6.21.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-21.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.21.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 6.21.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

6.21.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.21.4 Backup Method. None required.

6.21.5 System Securing. The CPG to pilot longitudinal F.S. 82.80 control bracket, if removed, requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

Figure 6-21. CPG to Pilot Longitudinal F.S. 82.80 Control Bracket

6-47
TM 1-1520-264-23

6.22 CPG TO PILOT COLLECTIVE F.S. 118.50 BELLCRANK (ET).

6.22.1 Description (Figure 6-1. Index No. 22). The CPG to pilot collective F.S. 118.50 bellcrank connects the CPG to

pilot's collective controls push-pull rod.

6.22.2 Defects. This inspection is used to verify crack indications found visually on the CPG to pilot collective F.S.

118.50 bellcrank. No cracks are allowed.

6.22.3 Primary Method. Eddy Current.

6.22.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.22.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the C PG to

pilot collective F.S. 11 8.50 bellcrank removed in accordance with the applicable technical manuals listed in Table 1-1.

6.22.3.3 Access. Not applicable.

6.22.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.22.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-48
TM 1-1520-264-23

6.22.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-22.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.22.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.22.3.5 b. (1), (2), and (3) shall be repeated each time a change is made.

6.22.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.22.4 Backup Method. None required.

6.22.5 System Securing. The CPG to pilot collective F.S. 118.50 bellcrank requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

Figure 6-22. CPG to Pilot Collective F.S. 118.50 Bellcrank

6-49
TM 1-1520-264-23

6.23 CPG DIRECTIONAL SHEAR PIN ACTIVATED DECOUPLER (SPAD) ARMS (ET).

6.23.1 Description (Figure 6-1. Index No. 23). The CPG directional SPAD arms are the two major structures making up

the CPG directional SPAD assembly. Inspect both arms.

6.23.2 Defects. This inspection is used to verify crack indications found visually on the CPG directional SPAD arms. No

cracks are allowed.

6.23.3 Primary Method. Eddy Current.

6.23.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.23.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the CPG

directional SPAD arms removed in accordance with the applicable technical manuals listed in Table 1-1.

6.23.3.3 Access. Not applicable.

6.23.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.23.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-50
TM 1-1520-264-23

6.23.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-23.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.23.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 6.23.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

6.23.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.23.4 Backup Method. None required.

6.23.5 System Securing. The CPG directional SPAD arms require installation in accordance with the applicable

technical manuals listed in Table 1-1.

Figure 6-23. CPG Directional Shear Pin Activated Decoupler (SPAD) Arms

6-51
TM 1-1520-264-23

6.24 DIRECTIONAL F.S. 121.40 BELLCRANK (ET).

6.24.1 Description (Figure 6-1. Index No. 24). The directional F.S. 121.40 bellcrank is located underneath the pilot's

station behind the pilot's floor panel.

6.24.2 Defects. This inspection is used to verify crack indications found visually on the directional F.S. 121.40

bellcrank. No cracks are allowed.

6.24.3 Primary Method. Eddy Current.

6.24.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.24.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the directional

F.S. 121.40 bellcrank removed in accordance with the applicable technical manuals listed in Table 1-1.

6.24.3.3 Access. Not applicable.

6.24.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.24.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-52
TM 1-1520-264-23

6.24.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-24.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.24.3.1 may be used depending primarily on the

ease of accessibility and user friendliness. If the probes are changed, steps 6.24.3.5 b.

(1), (2), and (3) shall be repeated each time a change is made.

6.24.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.24.4 Backup Method. None required.

6.24.5 System Securing. The directional F.S. 121.40 bellcrank requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

Figure 6-24. Directional F.S. 121.40 Bellcrank

6-53
TM 1-1520-264-23

6.25 DIRECTIONAL F.S. 121.40 BELLCRANK BRACKET (ET).

6.25.1 Description (Figure 6-1. Index No. 25). The directional F.S. 121.40 bellcrank bracket is located underneath the

pilot's station behind the pilot's floor panel. It supports the directional F.S. 121.40 bellcrank.

6.25.2 Defects. This inspection is used to verify crack indications found visually on the directional F.S. 121.40 bellcrank

bracket. No cracks are allowed.

6.25.3 Primary Method. Eddy Current.

6.25.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.25.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the directional

F.S. 121.40 bellcrank bracket removed in accordance with thi applicable technical manuals listed in Table 1-1.

6.25.3.3 Access. Not applicable.

6.25.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or

Area for NDI, paragraph 1.4.4.

6.25.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e'1.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-54
TM 1-1520-264-23

6.25.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-25.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.25.3.1 may be used depending primarily on the ease of

accessibility and user friendliness. If the probes are changed, steps 6.25.3.5 b. (1), (2), and (3) shall be

repeated each time a change is made.

6.25.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.25.4 Backup Method. None required.

6.25.5 System Securing. The directional F.S. 121.40 bellcrank bracket requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

Figure 6-25. Directional F.S. 121.40 Bellcrank Bracket

6-55
TM 1-1520-264-23

6.26 PILOT DIRECTIONAL SHEAR PIN ACTIVATED DECOUPLER (SPAD) TRANSDUCER

ARM (ET).

6.26.1 Description (Figure 6-1. Index No. 26). The pilot directional SPAD transducer arm is part of the pilot directional

SPAD assembly.

6.26.2 Defects. This inspection is used to verify crack indications found visually on the pilot directional SPAD transducer

arm. No cracks are allowed.

6.26.3 Primary Method. Eddy Current.

6.26.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.26.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the pilot

directional SPAD transducer arm removed in accordance with the applicable technical manuals listed in Table 1-1.

6.26.3.3 Access. Not applicable.

6.26.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.26.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos -20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe is

passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-56
TM 1-1520-264-23

6.26.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-26.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.26.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.26.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.26.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.26.4 Backup Method. None required.

6.26.5 System Securing. The pilot directional SPAD transducer arm requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

Figure 6-26. Pilot directional shear Pin activated Decoupler (SPAD) Transducer Arm

6-57
TM 1-1520-264-23

6.27 PILOT DIRECTIONAL SHEAR PIN ACTIVATED DECOUPLER (SPAD) REMOTE-CONTROL LEVER (ET).

6.27.1 Description (Figure 6-1. Index No. 27). The pilot directional SPAD remote control lever is part of the pilot

directional SPAD assembly.

6.27.2 Defects. This inspection is used to verify crack indications found visually on the pilot directional SPAD remote

control lever. No cracks are allowed.

6.27.3 Primary Method. Eddy Current.

6.27.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.27.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the pilot

directional SPAD remote control lever removed in accordance with the applicable technical manuals listed in Table 1-1.

6.27.3.3 Access. Not applicable.

6.27.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.27.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe is

passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-58
TM 1-1520-264-23

6.27.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-27.

a. Place probe on a good area in. the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.27.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.27.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.27.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.27.4 Backup Method. None required.

6.27.5 System Securing. The pilot directional SPAD remote control lever requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

Figure 6-27. Pilot Directional Shear Pin Activated Decoupler (SPAD) Remote Control Lever

6-59
TM 1-1520-264-23

6.28 PILOT DIRECTIONAL SHEAR PIN ACTI VATED DECOUPLER (SPAD) BELLCRANKS (ET).

6.28.1 Description (Figure 6-1. Index No. 28). The pilot directional SPAD bellcranks are part of the pilot directional

SPAD assembly. There are two bellcranks.

6.28.2 Defects. This inspection is used to verify crack indications found visually on the pilot directional SPAD

bellcranks. No cracks are allowed.

6.28.3 Primary Method. Eddy Current.

6.28.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.28.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance pilot directional

SPAD bellcranks removed and disassembled in accordance with the applicable technical manuals listed in Table 1-1.

6.28.3.3 Access. Not applicable.

6.28.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.28.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-60
TM 1-1520-264-23

6.28.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-28.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.28.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.28.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.28.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.28.4 Backup Method. None required.

6.28.5 System Securing. The pilot directional SPAD bellcranks require installation in accordance with the applicable

technical manuals listed in Table 1-1.

Figure 6-28. Pilot Directional Shear Pin Activated Decoupler (SPAD) Bellcranks

6-61
TM 1-1520-264-23

6.29 DIRECTIONAL F.S. 156.07 BELLCRANK (ET).

6.29.1 Description (Figure 6-1. Index No. 29). The directional F.S. 156.07 bellcrank is attached to the pilot collective

support.

6.29.2 Defects. This inspection is used to verify crack indications found visually on the directional F.S. 156.07

bellcrank. No cracks are allowed.

6.29.3 Primary Method. Eddy Current.

6.29.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.29.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the directional

F.S.156.07 bellcrank in accordance with the applicable technical manuals listed in Table 1-1.

6.29.3.3 Access. Not applicable.

6.29.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.29.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-62
TM 1-1520-264-23

6.29.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-29.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.29.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.29.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.29.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.29.4 Backup Method. None required.

6.29.5 System Securing. The directional F.S. 156.07 bellcrank requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

Figure 6-29. Directional F.S. 156.07 Bellcrank

6-63
TM 1-1520-264-23

6.30 DIRECTIONAL F.S. 159.98 BELLCRANK AND BRACKET (ET).

6.30.1 Description (Figure 6-1. Index No. 30). The directional F.S. 159.98 bellcrank and bracket are found on the

left side of the helicopter, just aft of the cockpit area and below the transmission deck.

6.30.2 Defects. This inspection is used to verify crack indications found visually on the directional F.S. 159.98

bellcrank and bracket. No cracks are allowed.

6.30.3 Primary Method. Eddy Current.

6.30.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.30.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the directional

F.S. 159.98 bellcrank and bracket removed in accordance with the applicable technical manuals listed in Table 1-1.

6.30.3.3 Access. Not applicable.

6.30.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.30.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-64
TM 1-1520-264-23

6.30.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-30.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.30.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.30.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.30.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.30.4 Backup Method. None required.

6.30.5 System Securing. The directional F.S. 159.98 bellcrank and bracket require installation in accordance with the

applicable technical manuals listed in Table 1-1.

Figure 6-30. Directional F.S. 159.98 Bellcrank and Bracket

6-65
TM 1-1520-264-23

6.31 DIRECTIONAL F.S. 164.33 BELLCRANK BRACKET AND ATTACHING AREA ON DECK (ET).

6.31.1 Description (Figure 6-1. Index No. 31). The directional F.S. 164.33 bellcrank bracket and attaching area on

deck are located on the left side of the helicopter, just behind the cockpit area.

6.31.2 Defects. This inspection is used to verify crack indications found visually on the directional F.S. 164.33

bellcrank bracket and attaching area on the deck. No cracks are allowed.

6.31.3 Primary Method. Eddy Current.

6.31.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.31.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the directional

F.S. 164.33 bellcrank bracket removed in accordance with the applicable technical manuals listed in Table 1-1.

6.31.3.3 Access. Not applicable.

6.31.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.31.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e".

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-66
TM 1-1520-264-23

6.31.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-31.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.31.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.31.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.31.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.31.4 Backup Method. None required.

6.31.5 System Securing. The directional F.S. 164.33 bellcrank bracket requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

Figure 6-31. Directional F.S. 164.33 Bellcrank Bracket and Attaching Area on Deck

6-67
TM 1-1520-264-23

6.32 PILOT LONGITUDINAL SHEAR PIN ACTIVATED DECOUPLER (SPAD) OUTER AND INNER LEVER (ET).

6.32.1 Description (Figure 6-1. Index No. 32). The pilot longitudinal SPAD outer and inner levers make up the major

parts of the pilot longitudinal SPAD assembly. There is one inner and one outer lever.

6.32.2 Defects. This inspection is used to verify crack indications found visually on the pilot longitudinal SPAD outer

and inner levers. No cracks are allowed.

6.32.3 Primary Method. Eddy Current.

6.32.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz,90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.32.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the pilot

longitudinal SPAD outer and inner lever removed in accordance with the applicable technical manuals listed in Table 1-1.

6.32.3.3 Access. Not applicable.

6.32.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.32.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-68
TM 1-1520-264-23

6.32.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-32.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.32.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.32.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.32.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.32.4 Backup Method. None required.

6.32.5 System Securing. The pilot longitudinal SPAD outer and inner levers require installation in accordance with the

applicable technical manuals listed in Table 1-1.

6.33 PILOTICPG DIRECTIONAL CONTROL PEDAL RELEASE HANDLE (ET).

6.33.1 Description (Figure 6-1. Index No. 33). The pilot/CPG directional control pedal release handles are differently

shaped but similar in function. Each handle is found in the pilot/CPG compartments, just forward of the cyclic control

sticks.

6.33.2 Defects. This inspection is used to verify crack indications found visually on the pilot/CPG directional control

pedal release handle. No cracks are allowed.

6.33.3 Primary Method. Eddy Current.

6.33.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90°1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.33.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the pilot/CPG directional control pedal release handle shall be

removed in accordance with the applicable technical manuals listed in Table 1-1.

6-69
TM 1-1520-264-23

Figure 6-32. Pilot Longitudinal Shear Pin Activated Decoupler

(SPAD) Outer and Inner Lever

6-70
TM 1-1520-264-23

6.33.3.3 Access. To access the directional control pedal release handle, remove the panels from the pilot's center

console and the pedal adjust cover in the CPG station.

6.33.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.33.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.33.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-33.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.33.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.33.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.33.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.33.4 Backup Method. None required.

6.33.5 System Securing. The pilot/CPG directional control pedal release handle, if removed, requires installation in

accordance with the applicable technical manuals listed in Table 1-1.

6-71
TM 1-1520-264-23

Figure 6-33. Pilot/CPG Directional Control Pedal Release Handle

6-72
TM 1-1520-264-23

6.34 PILOT/CPG DIRECTIONAL CONTROL PEDAL RELEASE SHAFT (MT).

6.34.1 Description (Figure 6-1. Index No. 34). The pilot and CPG directional control pedal release shafts connect the

pedal release handles to the directional control pedal release nuts. Each is similar in design and function.

6.34.2 Defects. This inspection is used to verify crack indications found visually on the pilot/CPG directional control

pedal release shaft. No cracks are allowed.

6.34.3 Primary Method. Magnetic Particle.

6.34.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

6.34.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using applicable positions of this procedure. If required, the pilot/CPG directional control pedal release

shaft shall be removed in accordance with the applicable technical manuals listed in Table 1-1.

6.34.3.3 Access. Access is through the center console panel (Figure 1-4, Item PL3).

6.34.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.34.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

6.34.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 6-34.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for

no more than five seconds.

d. Inspect for cracks using the black light.

6.34.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6-73
TM 1-1520-264-23

Figure 6-34. Pilot/CPG Directional Control Pedal Release Shaft

6-74
TM 1-1520-264-23

6.34.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

6.34.4 Backup Method. None required.

6.34.5 System Securing. Clean the pilot/CPG directional control pedal release shaft thoroughly to remove all residual

magnetic particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The

pilot/CPG directional control pedal release shaft, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

6.35 PILOT/CPG DIRECTIONAL CONTROL PEDAL RELEASE NUTS (MT).

6.35.1 Description (Figure 6-1. Index No. 35). The pilot and CPG directional control pedal release nuts connect the

pedal release handles to the shafts. Each is similar in design and function.

6.35.2 Defects. This inspection is used to verify crack indications found visually on the pilot/CPG directional control

pedal release nuts. No cracks are allowed.

6.35.3 Primary Method. Magnetic Particle.

6.35.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

6.35.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the pilot/CPG directional control pedal release nuts shall be removed

in accordance with the applicable technical manuals listed in Table 1-1.

6.35.3.3 Access. Access is through the center console panels (Figure 1-4, Items PL3 and PR4).

6.35.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.35.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

6-75
TM 1-1520-264-23

6.35.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. Positions required for this inspection are illustrated in Figure 6-35.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five

seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 6.35.3.8.

f. Repeat steps a. through e. for position 2.

6.35.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.35.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

6.35.4 Backup Method. None required.

6.35.5 System Securing. The pilot/CPG directional control pedal release nuts, if removed, require installation in

accordance with the applicable technical manuals listed in Table 1-1.

Figure 6-35. Pilot/CPG Directional Control Pedal Release Nuts

6-76
TM 1-1520-264-23

6.36 DIRECTIONAL F.S. 199.25 TAIL ROTOR FITTING (ET).

6.36.1 Description (Figure 6-1. Index No. 36). The directional F.S. 199.25 tail rotor fitting is attached to the

transmission deck. Outboard of the main transmission is a mounting point for one end of the F.S. 199.25 tail rotor

bellcrank.

6.36.2 Defects. This inspection is used to verify crack indications found visually on the directional F.S. 199.25 tail

rotor fitting. No cracks are allowed.

6.36.3 Primary Method. Eddy Current.

6.36.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.36.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the directional F.S. 199.25 tail rotor fitting shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

6.36.3.3 Access. Access is through the main rotor transmission panel (Figure 1-4, Item L200) and by removing F.S.

199.25 bellcrank.

6.36.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.36.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e11.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-77
TM 1-1520-264-23

6.36.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-36.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.36.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.36.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.36.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.36.4 Backup Method. None required.

6.36.5 System Securing. The directional F.S. 199.25 tail rotor fitting, if removed, requires installation in accordance with

the applicable technical manuals listed in Table 1-1.

Figure 6-36. Directional F.S. 199.25 Tail Rotor Fitting

6-78
TM 1-1520-264-23

6.37 DIRECTIONAL F.S. 275 ROTOR CONTROL BRACKET (ET).

6.37.1 Description (Figure 6-1, Index No. 37). The directional F.S. 275 rotor control bracket acts as a support for the

directional F.S. 275 bellcrank.

6.37.2 Defects. This inspection is used to verify crack indications found visually on the directional F.S. 275 rotor

control bracket. No cracks are allowed.

6.37.3 Primary Method. Eddy Current.

6.37.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.37.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance and the directional

F.S. 275 rotor control bracket removed in accordance with the applicable technical manuals listed in Table 1-1.

6.37.3.3 Access. Not applicable.

6.37.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.37.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”.

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

V Pos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-79
TM 1-1520-264-23

6.37.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-37.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.37.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.37.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.37.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.37.4 Backup Method. None required.

6.37.5 System Securing. The directional F.S. 275 rotor control bracket requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

Figure 6-37. Directional F.S. 275 Rotor Control Bracket

6-80
TM 1-1520-264-23

6.38 DIRECTIONAL F.S. 348 BELLCRANK (ET).

6.38.1 Description (Figure 6-1. Index No. 38). The directional F.S. 348 bellcrank attaches the forward and

directional control push-pull rods in the F.S. 348 area.

6.38.2 Defects. This inspection is used to verify crack indications found visually on the directional F.S. 348

bellcrank. No cracks are allowed.

6.38.3 Primary Method. Eddy Current.

6.38.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.38.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the directional F.S. 348 bellcrank shall be removed in accordance with

the applicable technical manuals listed in Table 1-1.

6.38.3.3 Access. Access is through the tail rotor shaft and deck area fairings (Figure 1-4, Items T325 and T355).

6.38.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.38.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e”

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-81
TM 1-1520-264-23

6.38.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-38.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.38.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.38.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.38.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.38.4 Backup Method. None required.

6.38.5 System Securing. The directional F.S. 348 bellcrank, if removed, requires installation in accordance with the

applicable technical manuals listed in Table 1-1.

Figure 6-38. Directional F.S. 348 Bellcrank

6-82
TM 1-1520-264-23

6.39 DIRECTIONAL F.S. 348 TAIL ROTOR BRACKET (ET).

6.39.1 Description (Figure 6-1. Index No. 39). The directional F.S. 348 tail rotor bracket mounts the F.S. 348

bellcrank in the F.S. 348 area.

6.39.2 Defects. This inspection is used to verify crack indications found visually on the directional F.S. 348 tail rotor

bracket. No cracks are allowed.

6.39.3 Primary Method. Eddy Current.

6.39.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.39.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the directional F.S. 348 tail rotor bracket shall be removed in

accordance with the applicable technical manuals listed in Table 1-1.

6.39.3.3 Access. Access is through the tail rotor shaft and deck area fairings (Figure 1 -4, Items T325 and T355).

6.39.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.39.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-1 9e".

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6-83
TM 1-1520-264-23

6.39.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-39.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

NOTE

Either probe identified in paragraph 6.39.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.39.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.39.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.39.4 Backup Method. None required.

6.39.5 System Securing. The directional F.S. 348 tail rotor bracket, if removed, requires installation in accordance with

the applicable technical manuals listed in Table 1-1.

Figure 6-39. Directional F.S. 348 Tail Rotor Bracket

6-84
TM 1-1520-264-23

6.40 TAIL ROTOR SWASHPLATE CONTROL BELLCRANK (MT).

6.40.1 Description (Figure 6-1. Index No. 40). The tail rotor swashplate control bellcrank is found just inboard of the

tail rotor swashplate. It connects the directional servocylinder to the swashplate.

6.40.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor swashplate control

bellcrank. No cracks are allowed.

6.40.3 Primary Method. Magnetic Particle.

6.40.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

6.40.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail rotor swashplate control bellcrank removed in accordance with

the applicable technical manuals listed in Table 1-1.

6.40.3.3 Access. Not applicable.

6.40.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.40.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

6.40.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. Positions required for this inspection are illustrated in Figure 6-40.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time.

Remove the media momentarily before removing the current. Current should be applied for no more than five

seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 6.40.3.8.

f. Repeat steps a. through e. for positions 2 and 3.

6.40.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6-85
TM 1-1520-264-23

Figure 6-40. Tail Rotor Swashplate Control Bellcrank

6.40.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

6.40.4 Backup Method. None required.

6.40.5 System Securing. Clean the tail rotor swashplate control bellcrank thoroughly to remove all residual magnetic

particle media. Refer to Post Cleaning and Restoration of Part or Area After NDI, paragraph 1.4.16. The tail rotor

swashplate control bellcrank, if removed, requires installation in accordance with the applicable technical manuals listed

in Table 1-1.

6.41 TAIL ROTOR DRIVE LINKS (ET).

6.41.1 Description (Figure 6-1. Index No. 41). There are two tail rotor drive links. The inspection is the same for

each. The tail rotor drive links are two-part links which connect the tail rotor swashplate to a controlling fork.

6.41.2 Defects. This inspection is used to verify crack indications found visually on the tail rotor drive links. No

cracks are allowed.

6.41.3 Primary Method. Eddy Current.

6-86
TM 1-1520-264-23

6.41.3.1 NDI Equipment and Materials. (Refer to Appendix B.)

a. Eddy Current Inspection Unit

b. Probe, straight, shielded surface, 100 KHz-500 KHz

c. Probe, right angle, shielded surface, 100 KHz-500 KHz, 90° 1/2 inch drop

d. Cable Assembly

e. Reference Block, three-notched aluminum (0.008, 0.020, and 0.040 EDM notches)

f. Teflon Tape, refer to Table 1-8

g. Aircraft Marking Pencil, refer to Table 1-8

6.41.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial inspection

for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed surfaces of

the installed part using this procedure. If required, the tail rotor drive links shall be removed in accordance with the

applicable technical manuals listed in Table 1-1.

6.41.3.3 Access. Not applicable.

6.41.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.41.3.5 NDI Equipment Settings.

a. Make the following initial settings on the Eddy Current Inspection Unit, NORTEC-19e".

Frequency F1 - 200 KHz F2 - off

HdB - 57.0

VdB - 69.0

Rot - 56°

Probe drive - mid

LPF - 100

HPF - 0

H Pos - 80%

VPos - 20%

b. Refer to Eddy Current Method, paragraph 1.4.11. Set up on test block as follows:

(1) Null probe on test block.

(2) Adjust phase as required to obtain horizontal lift-off.

(3) Move probe over all three notches in test block. Adjust gain to obtain a three block vertical signal when probe

is passed over 0.040-inch notch in test block. (See the standard instrument display shown in Figure 1-7.)

6.41.3.6 Inspection Procedure. Refer to Eddy Current Method, paragraph 1.4.11 and Figure 6-41.

a. Place probe on a good area in the inspection location and null. Adjust phase as required to obtain horizontal liftoff.

b. Inspect the part.

c. Any signal similar to the notches in the test block is cause for rejection.

6-87
TM 1-1520-264-23

Figure 6-41. Tail Rotor Drive Links

NOTE

Either probe identified in paragraph 6.41.3.1 may be used depending primarily on the ease of accessibility and user

friendliness. If the probes are changed, steps 6.41.3.5 b. (1), (2), and (3) shall be repeated each time a change is

made.

6.41.3.7 Marking and Recording of Inspection Results. Mark and record the inspection results as required by

paragraph 1.3.

6.41.4 Backup Method. None required.

6.41.5 System Securing. The tail rotor drive links, if removed, require installation in accordance with the applicable

technical manuals listed in Table 1-1.

6.42 EXTERIOR SURFACES OF ALL FERROUS HYDRAULIC COMPONENTS (SERVOCYLINDERS,

ACTUATORS, RESERVOIRS, ETC.) (MT).

6.42.1 Description (Figure 6-1. Index No. 42). Inspect the exterior surfaces of all ferrous hydraulic components

(servocylinders, actuators, reservoirs, etc.) found in the areas of the aft/forward main rotor mast and the aft/above top

rotor mast.

6.42.2 Defects. This inspection is used to verify crack indications found visually on the exterior surfaces of all

ferrous hydraulic components. No cracks are allowed.

6-88
TM 1-1520-264-23

6.42.3 Primary Method. Magnetic Particle.

6.42.3.1 NDI Equipment and Materials . (Refer to Appendix B.)

a. Magnetic Particle Inspection Probe/Yoke

b. Magnetometer

c. Black Light

d. Fluorescent Magnetic Particles, refer to Table 1-8

e. Consumable Materials, refer to Table 1-8

f. Aircraft Marking Pencil, refer to Table 1-8

NOTE

Hand-held magnetic coil may be used. Refer to paragraph 1.4.8.1.2 and Figure 1-6.

6.42.3.2 Preparation of Helicopter. The helicopter shall be prepared for safe ground maintenance. A partial

inspection for cause (visual indications, sites of mechanical damage, corrosion, etc.) may be performed on all exposed

surfaces of the installed part using applicable positions of this procedure. If required, the hydraulic components

(servocylinders, actuators, reservoirs, etc.) shall be removed in accordance. with the applicable technical manuals listed

in Table 1-1.

6.42.3.3 Access. Not applicable.

6.42.3.4 Preparation of Part. The part shall be thoroughly cleaned. Refer to Preparation of Part or Area for NDI,

paragraph 1.4.4.

6.42.3.5 NDI Equipment Settings. Refer to Magnetic Particle Method, paragraph 1.4.8.

6.42.3.6 Inspection Procedure. A magnetic field shall be applied to the part perpendicular to the orientation of

possible cracks. The position required for this inspection is illustrated in Figure 6-42.

a. Select AC on the AC/DC power switch.

b. Place probe/yoke on part in position 1 as shown.

c. Press the test switch and apply a light coat of magnetic particle media at the same time. Remove the

media momentarily before removing the current. Current should be applied for no more than five

seconds.

d. Inspect for cracks using the black light.

e. Demagnetize before moving to the next position. Refer to paragraph 6.42.3.8.

f. Repeat steps a. through e. for other positions, as required.

6.42.3.7 Marking and Recording of Inspection Results . Mark and record the inspection results as required by

paragraph 1.3.

6.42.3.8 Demagnetization. With the switch remaining in the AC position, place the probe/yoke legs in the same

position used for magnetizing. Press the test switch and withdraw the probe/yoke from the part for a distance of two feet

before releasing the switch.

6-89
TM 1-1520-264-23

6.42.4 Backup Method. None required.

6.42.5 System Securing. Clean the exterior surfaces of all ferrous hydraulic components (servocylinders, actuators,

reservoirs, etc.) thoroughly to remove all residual magnetic particle media. Refer to Post Cleaning and Restoration of

Part or Area After NDI, paragraph 1.4.16. Any part, if removed, requires installation in accordance with the applicable

technical manuals listed in Table 1-1.

Figure 6-42. Exterior Surfaces of All Ferrous Hydraulic Components

(Servocylinders, Actuators, Reservoirs, etc.)

6-90
(4)

MAINTENANCE CATEGORY

(5)

INSPECTION

EQUIPMENT

REQUIREMENTS

(3)

INSPECT

FOR

(6)

REMARKS

(2)

COMPONENT

ASSEMBLY

(1)

PROCEDURE

NUMBER

TM 1-1520-264-23

APPENDIX A

MAINTENANCE ALLOCATION CHART

NONDESTRUCTIVE INSPECTION

NDI METHODS/EQUIPMENT

001 Fluorescent Penetrant Method

002 Magnetic Particle Method

003 Eddy Current Method

004 Ultrasonic Method

005 Bond Testing Method

006 Radiographic Method

NOMENCLATURE OF END ITEMS

HELICOPTER, AH-64A Series

2.2 Main Rotor Droop Stop Cracks √ 001

Follower (Plunger)

2.3 Droop Stop Ring Cracks √ 002

2.4 Main Rotor Blade Voids √ 005

(Voids)

2.5 Main Rotor Blade Cracks √ 001

2.6 Main Rotor Blade Fluid √ 006

2.7 Main Rotor Blade Cracks √ 003

Weight Support Fittings

2.8 Main Rotor Mast Cracks √ 002

2.9 Main Rotor Mast Cracks √ 002

Retaining Ring

2.10 Main Rotor Hub Cracks √ 002

Retention Nut

2.11 Main Rotor Head (Hub) Cracks 003

2.12 Main Rotor Lead Lag Cracks √ 003

Link (Damper Link)

2.13 Main Rotor Damper Cracks √ 003

2.14 Main Rotor Damper Cracks √ 003

Trunnion

2.15 ' Main Rotor Damper Rod Cracks √ 002

End

2.16 Main Rotor Pitch Cracks √ 003

Housing

2.17 Main Rotor Feathering Cracks √ 003

Bearing Housing

2.18 Main Rotor Striker Plate Cracks √ 002

and Shims

A-1

AVUM AVIM DEPOT
(4)

MAINTENANCE CATEGORY

(5)

INSPECTION

EQUIPMENT

REQUIREMENTS

(3)

INSPECT

FOR

(6)

REMARKS

(2)

COMPONENT

ASSEMBLY

(1)

PROCEDURE

NUMBER AVUM AVIM DEPOT

TM 1-1520-264-23

NOMENCLATURE OF END ITEMS

HELICOPTER, AH-64A Series

2.19 Main Rotor Hub Cracks √ 003

Bearing

2.20 Main Rotor Lower Shoe Cracks √ 003

2.21 Main Rotor Head Hub Cracks √ 002

Load Plate

2.22 Main Rotor Hub Cracks √ 002

Brackets

2.23 Main Rotor Hub Lower Cracks √ 002

Plate

2.24 Tail Rotor Fork Cracks √ 003

Assembly (Head and

Teeter Stop)

2.25 Tail Rotor Blade Cracks √ 001

2.26 Tail Rotor Blade (Voids) Voids √ 005

2.27 Tail Rotor Blade (Fluid) Fluid √ 006

2.28 Tail Rotor Hub Cracks √ 003

2.29 Tail Rotor Clamps and Cracks √ 003

Locking Plates

3.2 Drive Shafts Cracks √ 003 Backup

001

3.3 Drivetrain Couplings Cracks √ 003

3.4 Drivetrain Flanges Cracks √ 002

3.5 Damper and Anti-Flail Cracks √ 003 Backup

Supports 001

3.6 Forward Hanger Cracks √ 002 Backup

Bearing Flange 001

3.7 Forward Hanger Cracks √ 003 Backup

Bearing Support 001

3.8 Aft Hanger Bearing Cracks √ 002 Backup

Flange 001

3.9 Aft Hanger Bearing Cracks √ 003

Support

3.10 Intermediate Gearbox Cracks √ 003

Centrifugal Fan

3.11 Engine Nose Gearbox Cracks √ 003 Backup

001

A-2

A-2
TM 1-1520-264-23

NOMENCLATURE OF END ITEMS

HELICOPTER, AH-64A Series

3.12 Engine Nose Gearbox Cracks √ 002

Input Quill Shaft

3.13 Main Transmission Cracks √ 003

3.14 Main Transmission Cracks √ 003

Compressor Drive

Adapter

3.15 Main Transmission' APU Cracks √ 002

Drive Flange

3.16 Main Transmission Cracks √ 002

Tail Rotor Drive Flange

3.17 Main Rotor Gearshaft Cracks √ 002

Drive Gear Teeth

3.18 Main Rotor Mast Cracks √ 003

Support Base

3.19 Intermediate Gearbox Cracks √ 003

3.20 Intermediate Gearbox Cracks √ 003 Backup

Retainers 001

3.21 Intermediate Gearbox Cracks √ 002

Flange and Shouldered

Shaft

3.22 Tail Rotor Gearbox Cracks √ 003 Backup

001

3.23 Tail Rotor Gearbox Cracks √ 002

Shouldered Shaft

3.24 Tail Rotor Gearbox Cracks √ 003 Backup

Retainers 001

3.25 Tail Rotor Gearbox Cracks √ 002

Forward and Aft Strut

3.26 Tail Rotor Gearbox Cracks √ 002

Forward and Aft Strut

Fittings

3.27 Main Rotor Head (Hub) Cracks √ 003

3.28 Main Rotor Support Cracks √ 002

Mast

4.2 Fuselage and Empen- Cracks √ 003

nage Access Doors,

Covers, Panels, and

Fairings - Metal

A-3

(4)

MAINTENANCE CATEGORY

(5)

INSPECTION

EQUIPMENT

REQUIREMENTS

(3)

INSPECT

FOR

(6)

REMARKS

(2)

COMPONENT

ASSEMBLY

(1)

PROCEDURE

NUMBER AVUM AVIM DEPOT
TM 1-1520-264-23

NOMENCLATURE OF END ITEMS

HELICOPTER, AH-64A Series

4.3 Honeycomb Core Fuse- Voids √ 005

lage Panels, Vertical

Fin, etc.

4.4 Fluid in Honeycomb Fluid √ 006

Core Fuselage Panels,

Vertical Fin, etc.

4.5 Fittings, Castings, and Cracks √ 003 Backup

Forgings 001

4.6 Transmission Deck Cracks √ 003

4.7 Empennage Frame Cracks √ 003

Assemblies F.S. 530

and F.S. 547 and

Attached Stringers

4.8 Fuselage Support Holes Cracks √ 003

4.9 Gun and Ammo Cracks √ 003

Support Mount Pads

4.10 Main Landing Gear Cracks √ 002

Shock Strut Support

4.11 Main Landing Gear Cracks √ 002

Cross Tube Mounting

Points

4.12 Rotor Support Mixer Cracks √ 002

Assembly and Mounting

Surfaces

4.13 Rotor Mixer Support Cracks √ 002

Assembly Bolt

4.14 Transmission Rotor Cracks √ 003

Support Strut

Assemblies

4.15 Nacelle Carry-Through Cracks √ 003

Post Assembly

4.16 Wing Attachment Cracks √ 003

Fittings on Wing and

Fuselage

4.17 Wing Rack Attachment Cracks √ 003

Points/Mounts

4.18 TADSIPNVS Support Fitting Cracks √ 003

A-4

(4)

MAINTENANCE CATEGORY

(5)

INSPECTION

EQUIPMENT

REQUIREMENTS

(3)

INSPECT

FOR

(6)

REMARKS

(2)

COMPONENT

ASSEMBLY

(1)

PROCEDURE

NUMBER AVUM AVIM DEPOT
TM 1-1520-264-23

NOMENCLATURE OF END ITEMS

HELICOPTER, AH-64A Series

4.19 Vertical Stabilizer Lugs Cracks √ 003

4.20 Vertical Stabilizer Cracks √ 002

Barrel Nuts

4.21 Horizontal Stabilator Cracks √ 003

Actuator Fitting

4.22 Engine Access and Cracks √ 001

Ventilation Door Assembly Rig Connecting Link

4.23 Aft Inboard Engine Cracks √ 003

Mount Support

4.24 Engine Nacelle Strut Cracks √ 003

Attachment Area

4.25 Main Landing Gear Cracks V 002

Trailing Arms

4.26 Main Landing Gear Cracks √

Wheels

4.27 Main Landing Gear Cracks √ 002

Shock Strut Housing,

Piston, and Rod Ends

4.28 Main Landing Gear Cracks √ 003

Lower Structural

Support

4.29 Main Landing Gear Jack Cracks √ 002

Pad Adapter

4.30 Main Landing Gear Cracks √ 002

Trailing Arm Cross Tube

4.31 Main Landing Gear Cracks √ 002

Shock Strut Mount Shaft

4.32 Tail Landing Gear Fork Cracks √ 003

4.33 Tail Wheel Cracks √ 003

4.34 Tail Landing Gear Cracks √ 002

Shock Strut

4.35 Tail Landing Gear Cracks √ 003

Trailing Arms

4.36 Tail Landing Gear Cracks √ 003

Actuating Cylinder

Assembly

4.37 Brake System Cracks √ 001

Components

A-5

(4)

MAINTENANCE CATEGORY

(5)

INSPECTION

EQUIPMENT

REQUIREMENTS

(3)

INSPECT

FOR

(6)

REMARKS

(2)

COMPONENT

ASSEMBLY

(1)

PROCEDURE

NUMBER AVUM AVIM DEPOT
TM 1-1520-264-23

NOMENCLATURE OF END ITEMS

HELICOPTER, AH-64A Series

4.38 General Helicopter Cracks √ 002

Attaching Hardware

5.2 Aft Inboard and Aft Cracks √ 003

Lower Engine Mounts

5.3 Forward Inboard Cracks √ 002

Engine Mount

5.4 Forward Lower Engine Cracks √ 002

Mount

5.5 Engine Tubing, Cou- Cracks √ 001

plings, Air Ducts, Fittings, Supports, Brackets, and Clips

5.6 Ai, Inlet Assembly Cracks √ 003

5.7 Engine Air Inlet "V" Cracks √ 001

Band Clamp

5.8 Starter Flange Cracks √ 003

5.9 Engine Shroud Cracks √ 001

5.10 Engine Load Demand Cracks √ 003

Spindle Bellcrank

Support

5.11 Engine Components Cracks √ 001

6.2 'Flight Control Cracks √ 003

Bellcranks

6.3 Main Rotor Swashplate Cracks √ 003

Shoulder Pin Mating

Bores

6.4 Main Rotor Link Barrels Cracks √ 002 Backup

001

6.5 Main Rotor Scissors Cracks √ 003

Upper Arm

6.6 Main Rotor Scissors Cracks √ 003

Lower Arm

6.7 Pilot/CPG Collective Cracks √ 003

Stick Tube

A-6

(4)

MAINTENANCE CATEGORY

(5)

INSPECTION

EQUIPMENT

REQUIREMENTS

(3)

INSPECT

FOR

(6)

REMARKS

(2)

COMPONENT

ASSEMBLY

(1)

PROCEDURE

NUMBER AVUM AVIM DEPOT
TM 1-1520-264-23

NOMENCLATURE OF END ITEMS

HELICOPTER, AH-64A Series

6.8 Pilot/CPG Collective Cracks √ 003

Stick Rotor Housing

6.9 Pilot Collective Stick Cracks √ 003

Cylinder

6.10 Flight Control Rods, Cracks √ 003

Connecting Links, Rod

Ends, Clevises, Levers

and Attaching Parts

6.11 Pilot Collective Stick Cracks √ 003

Support Assembly

6.12 CPG Collective Stick Cracks √ 003

Support Assembly

6.13 Pilot Cyclic Stick Cracks √ 003

6.14 Lateral Feel Spring Cracks √ 003

Cartridge

6.15 Pilot Cyclic Stick Cracks √ 003

Housing and Support

Assembly

6.16 CPG Cyclic Stick Cracks √ 003

Forward and Aft Links

6.17 CPG Cyclic Stick Cracks √ 003

Remote Control Lever

6.18 CPG Cyclic Stick Fitting Cracks √ 003

Assembly

6.19 Ferrous Flight Control Cracks √ 002

System Push-Pull Rods

6.20 Nonferrous Flight Cracks √ 003

Control System PushPull Rods

6.21 CPG to Pilot Cracks √ 003

Longitudinal F.S. 82.80

Control Bracket

6.22 CPG to Pilot Collective Cracks √ 003

F.S. 118.50 Bellcrank

6.23 CPG Directional Shear Cracks √ 003

Pin Activated Decoupler

(SPAD) Arms

6.24 Directional F.S. 121.40 Cracks √ 003

Bellcrank

A-7

(4)

MAINTENANCE CATEGORY

(5)

INSPECTION

EQUIPMENT

REQUIREMENTS

(3)

INSPECT

FOR

(6)

REMARKS

(2)

COMPONENT

ASSEMBLY

(1)

PROCEDURE

NUMBER AVUM AVIM DEPOT
TM 1-1520-264-23

NOMENCLATURE OF END ITEMS

HELICOPTER, AH-64A Series

6.25 Directional F.S. 121.40 Cracks √ 003

Bellcrank Bracket

6.26 Pilot Directional Shear Cracks √ 003

Pin Activated Decoupler

(SPAD) Transducer Arm

6.27 Pilot Directional Shear Cracks √ 003

Pin Activated Decoupler

(SPAD) Remote Control

Lever

6.28 Pilot Directional Shear Cracks √ 003

Pin Activated Decoupler

(SPAD) Bellcranks

6.29 Directional F.S. 156.07 Cracks √ 003

Bellcrank

6.30 Directional F.S. 159.98 Cracks √ 003

Bellcrank and Bracket

6.31 Directional F.S. 164.33 Cracks √ 003

Bellcrank Bracket and

Attaching Area on Deck

6.32 Pilot Longitudinal Shear Cracks √ 003

Pin Activated Decoupler

(SPAD) Outer and Inner

Lever

6.33 Pilot/CPG Directional Cracks √ 003

Control Pedal Release

Handle

6.34 Pilot/CPG Directional Cracks √ 002

Control Pedal Release

Shaft

6.35 Pilot/CPG Directional Cracks √ 002

Control Pedal Release

Nuts

6.36 Directional F.S. 199.25 Cracks √ 003

Tail Rotor Fitting

6.37 Directional F.S. 275 Cracks √ 003

Rotor Control Bracket

6.38 Directional F.S. 348 Cracks √ 003

Bellcrank

A-8

(4)

MAINTENANCE CATEGORY

(5)

INSPECTION

EQUIPMENT

REQUIREMENTS

(3)

INSPECT

FOR

(6)

REMARKS

(2)

COMPONENT

ASSEMBLY

(1)

PROCEDURE

NUMBER AVUM AVIM DEPOT
TM 1-1520-264-23

NOMENCLATURE OF END ITEMS

HELICOPTER, AH-64A Series

6.39 Directional F.S. 348 Tail Cracks √ 003

Rotor Bracket

6.40 Tail Rotor Swashplate Cracks √ 002

Control Bellcrank

6.41 Tail Rotor Drive Links Cracks √ 003

6.42 Exterior Surfaces of All Cracks √ 002

Ferrous Hydraulic

Components (Servocylinders, Actuators,

Reservoirs, etc.)

A-9/(A-10)

(4)

MAINTENANCE CATEGORY

(5)

INSPECTION

EQUIPMENT

REQUIREMENTS

(3)

INSPECT

FOR

(6)

REMARKS

(2)

COMPONENT

ASSEMBLY

(1)

PROCEDURE

NUMBER AVUM AVIM DEPOT
TM 1-1520-264-23

APPENDIX B

EQUIPMENT LISTING

Part Number/ National Stock

Nomenclature Specification Manufacturer Number

Fluorescent Penetrant

Method

Fluorescent Penetrant MIL-1-25135 General Services 6850-00-703-7406

Inspection Kit Type I, Method C, Administration (GSA)

Level 3

Black Light UV Kit FMI Spectronics Corp. 6635-00-566-5198

956 Brush Hollow Rd.

Westbury, NY 11590-1731

Black Light Meter J-221 Ultraviolet Products Inc., 6695-00-488-5451

DBA UVP Inc.

5100 Walnut Grove Ave.

P.O. Box 1500

Upland, CA 91778

Black Light Bulbs A-A-1765 General Services 6240-00-233-3680

Administration (GSA)

Filter UV 3901 Magnaflux Div. of Illinois 6635-00-736-5177

Tool Works Inc.

1301 W Ainsle St.

Chicago, IL 60656

Magnetic Particle

Method

Yoke and Coil Kit YL-61 Magnaflux Div. of Illinois 4920-01-145-3924

Tool Works Inc.

1301 W. Ainsle St.

Chicago, IL 60656

Black Light ZB26 Spectronics Corp. 6635-00-611-5617

956 Brush Hollow Rd.

Westbury, NY 11590-1731

Magnetic Particle DA200 Parker Research Corp. 6635-00-022-0372

Inspection Probe 2642 Enterprise Rd.

Clearwater, FL 33575-1917

Magnetometer 2480 Sterling Mfg. Co. 6635-00-391-0058

1845 E. 30th St.

Cleveland, OH 44114-4438

B-1
TM 1-1520-264-23

Part Number/ National Stock

Nomenclature Specification Manufacturer Number

Eddy Current Method

Eddy Current Inspection NORTEC-19e11 Staveley Instruments, Inc. 6635-01-419-0694

Unit 421 North Quay St.

Kennewick, WA 99336

Cable Assembly, Coaxial CBM-6 NDT Engineering Corp. 5995-01-278-1271

6-feet long (1 required) 7056 S. 220th St.

Kent, WA 98032

Reference Block- TBS-1 Staveley Instruments, Inc.

Three-Notched Aluminum 1902510 421 North Quay St.

Kennewick, WA 99336

Reference Block- SRS-0824T NDT Engineering Corp.

Three-Notched Titanium 7056 S. 220TH St.

Kent, WA 98032

Reference Block- SRS-0824M NDT Engineering Corp.

Three-Notched 7056 S. 220TH St.

Magnesium Kent, WA 98032

Reference Block- 1902474 Staveley Instruments, Inc.

Block of Six 421 North Quay St.

Conductivity Sample Kennewick, WA 99336

Probe, right angle, MT-905-60 NDT Engineering Corp.

shielded surface 7056 S. 220th St.

P/100 KHz-500 KHz/ Kent, WA 98032

A/90.5/6

Probe, straight, MP-60 NDT Engineering Corp.

shielded surface 7056 S. 220th St.

P/100 KHz-500 KHz/ Kent, WA 98032

A/0.0/4

Ultrasonic Method

Ultrasonic Inspection Unit USD 15S KrautKramer Branson 6635-01-417-5467

50 Industrial Park Road

Lewistown, PA 17044

Transducer, 5.0 MHz 6635-01-057-2761

60 degree shear wave

1/4x1/4 inch element

B-2
TM 1-1520-264-23

Part Number/ National Stock

Nomenclature Specification Manufacturer Number

Bond Testing Method

Bondmaster 9016600- 99 Staveley Instruments, Inc. 6635-01-432-9954

421 North Quay St.

Kennewick, WA 99336

Cable Assembly SBM-CPM-P11 Staveley Instruments, Inc.

9117789 421 North Quay St.

Kennewick, WA 99336

Probe, Mechanical S-MP-4 Staveley Instruments, Inc.

Impedance Analysis 9317808 421 North Quay St.

Kennewick, WA 99336

Probe Holder, spring loaded BMM-H Staveley Instruments, Inc. 6635-01-407-8842

9316874 421 North Quay St.

Kennewick, WA 99336

Test Block, Composite 1916451 Staveley Instruments, Inc.

Defect Standard #1 421 North Quay St.

Kennewick, WA 99336

Test Block, Composite 1916453 Staveley Instruments, Inc. 

Defect Standard #3 421 North Quay St.

Kennewick, WA 99336

Test Block, Aluminum Refer to Appendix C

Honeycomb with 0.020-

inch thick aluminum/fiberglass skin

Test Block, Aluminum Refer to Appendix C

Honeycomb with 0.040-

inch thick aluminum skin

Test Block, Aluminum Refer to Appendix C

Honeycomb with 0.063-

inch thick aluminum skin

Radiographic Method

Tripod PDSANE480 Staveley Aerospace 6635-01-067-6315

X-Ray Tubehead Stand Systems, Inc.

Chatsworth, CA 91311

AIX Warning Light W/Stand 153001 American Industrial X-ray Inc. 6210-01-374-4594

B-3
TM 1-1520-264-23

Part Number/ National Stock

Nomenclature Specification Manufacturer Number

X-Ray Unit (LPX-160 3-000-0723 LORAD Corp. 6635-01-417-1830

water-cooled digital) 36 Apple Ridge Rd.

P.O. Box 710

Danbury, CT 06813-0710

B-4
TM 1-1520-264-23

APPENDIX C

ILLUSTRATED FIELD MANUFACTURE ITEMS LIST

Introduction

A. This appendix contains complete instructions for manufacturing nondestructive inspection support accessories in

the field.

B. An index order is provided for cross-referencing the number of the item to be manufactured to the figure number

which covers fabrication criteria.

C. All bulk materials needed for manufacture of an item are listed by part number or specification number.

D. See Figure C-1.

Item

Number Support Accessories

WS-2 Test block with aluminum honeycomb (0.75 or 1.0 inch) between 0.020 fiberglass skin

and a 0.063 aluminum skin

WS-4 Test block with aluminum honeycomb (0.75 or 1.0 inch) between a 0.040 aluminum skin

and a 0.020 skin

NOTES

1. All dimensions ,+/-) 1/16 inch. Break all sharp edges and corners.

2. Scuff sand the adhesive side of the fiberglass panel.

3. Scotchbrite scuff and alcohol/acetone rinse the adhesive side of the aluminum panels.

4. Milling or grinding of core cutouts is preferable over crushing techniques. A rotary file or end

mill cutter should produce acceptable results.

5. Polyolefin disks (inserts) should be flush with core if not slightly recessed.

6. Mix adhesives per manufacturer's instructions; exercise caution applying around inserts.

7. Moderate weight should be applied to the panels throughout the cure cycle.

BULK MATERIALS

1. 2024-T3 aluminum panels (0.020, 0.040 and 0.063 inch thick) specification QQ-4-250/5

2. Fiberglass panel 0.020 inch thick, specification MIL-1-24768/27

3. Aluminum honeycomb core 0.75 or 1.0 inch thick, 1/8 cell size specification MIL-C-7438-G

4. Polyolefin disks 0.025-0.030 inch thick (High-Density Polyethylene or Polypropylene)

5. Adhesive EA934 or equivalent

C-1
TM 1-1520-264-23

Figure C-1. Composite Test Blocks

C-2
TM 1-1520-264-23

INDEX

Subject Paragraph Page

Number Number

A

Aft Hanger Bearing Flange (MT) .......................................................................................3.8 3-17

Backup Method ........................................................................................................3.8.4 3-18

Defects ....................................................................................................................3.8.2 3-17

Description ...............................................................................................................3.8.1 3-17

Primary Method .......................................................................................................3.8.3 3-17

System Securing ......................................................................................................3.8.5 3-18

Aft Hanger Bearing Support (ET) .......................................................................................3.9 3-18

Backup Method ........................................................................................................3.9.4 3-22

Defects ....................................................................................................................3.9.2 3-18

Description ...............................................................................................................3.9.1 3-18

Primary Method .......................................................................................................3.9.3 3-18

System Securing ......................................................................................................3.9.5 3-22

Aft Inboard and Aft Lower Engine Mounts (ET) ..................................................................5.2 5-3

Backup Method ........................................................................................................5.2.4 5-4

Defects ....................................................................................................................5.2.2 5-3

Description ...............................................................................................................5.2.1 5-3

Primary Method .......................................................................................................5.2.3 5-3

System Securing ......................................................................................................5.2.5 5-4

Aft Inboard Engine Mount Support (ET) ...........................................................................4.23 4-52

Backup Method ......................................................................................................4.23.4 4-54

Defects ..................................................................................................................4.23.2 4-52

Description .............................................................................................................4.23.1 4-52

Primary Method .....................................................................................................4.23.3 4-52

System Securing ....................................................................................................4.23.5 4-54

Airframe and Landing Gear System .....................................................................................4 4-1

Air Inlet Assembly (ET) .....................................................................................................5.6 5-10

Backup Method ........................................................................................................5.6.4 5-12

Defects ....................................................................................................................5.6.2 5-10

Description ...............................................................................................................5.6.1 5-10

Primary Method .......................................................................................................5.6.3 5-10

System Securing ......................................................................................................5.6.5 5-12

B

Brake System Components (PT) .....................................................................................4.37 4-82

Backup Method ......................................................................................................4.37.4 4-84

Defects ..................................................................................................................4.37.2 4-82

Description .............................................................................................................4.37.1 4-82

Primary Method .....................................................................................................4.37.3 4-82

System Securing ....................................................................................................4.37.5 4-84

Index 1
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

C

CPG Collective Stick Support Assembly (ET) ..................................................................6.12 6-25

Description .............................................................................................................6.12.1 6-25

Defects ..................................................................................................................6.12.2 6-25

Primary Method .....................................................................................................6.12.3 6-25

Backup Method ......................................................................................................6.12.4 6-26

System Securing ....................................................................................................6.12.5 6-26

CPG Cyclic Stick Fitting Assembly (ET)...........................................................................6.18 6-38

Description .............................................................................................................6.18.1 6-38

Backup Method ......................................................................................................6.18.4 6-39

Defects ..................................................................................................................6.18.2 6-38

Primary Method .....................................................................................................6.18.3 6-38

System Securing ....................................................................................................6.18.5 6-39

CPG Cyclic Stick Forward and Aft Links (ET) ..................................................................6.16 6-34

Backup Method ......................................................................................................6.16.4 6-35

Defects ..................................................................................................................6.16.2 6-34

Description .............................................................................................................6.16.1 6-34

Primary Method .....................................................................................................6.16.3 6-34

System Securing ....................................................................................................6.16.5 6-35

CPG Cyclic Stick Remote Control Lever (ET) ..................................................................6.17 6-35

Backup Method ......................................................................................................6.17.4 6-37

Defects ..................................................................................................................6.17.2 6-35

Description .............................................................................................................6.17.1 6-35

Primary Method .....................................................................................................6.17.3 6-35

System Securing ....................................................................................................6.17.5 6-37

CPG Directional Shear Pin Activated Decoupler (SPAD) Arms (ET-) ..............................6.23 6-50

Backup Method ......................................................................................................6.23.4 6-51

Defects ..................................................................................................................6.23.2 6-50

Description .............................................................................................................6.23.1 6-50

Primary Method .....................................................................................................6.23.3 6-50

System Securing ....................................................................................................6.23.5 6-51

CPG to Pilot Collective F.S.118.50 Bellcrank (ET) ..........................................................6.22 6-48

Backup Method ......................................................................................................6.22.4 6-49

Defects ..................................................................................................................6.22.2 6-48

Description .............................................................................................................6.22.1 6-48

Primary Method .....................................................................................................6.22.3 6-48

System Securing ....................................................................................................6.22.5 6-49

CPG to Pilot Longitudinal F.S.82.80 Control Bracket (ET) ...............................................6.21 6-46

Backup Method ......................................................................................................6.21.4 6-47

Defects ..................................................................................................................6.21.2 6-46

Description .............................................................................................................6.21.1 6-46

Primary Method .....................................................................................................6.21.3 6-46

System Securing ....................................................................................................6.21.5 6-47

Index 2
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

D

Damper and Anti-Flail Supports (ET)..................................................................................3.5 3-11

Backup Method.........................................................................................................3.5.4 3-12

Defects .....................................................................................................................3.5.2 3-11

Description ...............................................................................................................3.5.1 3-11

Primary Method ........................................................................................................3.5.3 3-11

System Securing...................................................................................................... 3.5.5 3-12

Directional F.S121.40 Bellcrank (ET) ...............................................................................6.24 6-52

Backup Method.......................................................................................................6.24.4 6-53

Defects ...................................................................................................................6.24.2 6-52

Description..............................................................................................................6.24.1 6-52

Primary Method ......................................................................................................6.24.3 6-52

System Securing.....................................................................................................6.24.5 6-53

Directional F.S.121.40 Bellcrank Bracket (ET) .................................................................6.25 6-54

Backup Method.......................................................................................................6.25.4 6-55

Defects ...................................................................................................................6.25.2 6-54

Description..............................................................................................................6.25.1 6-54

Primary Method ......................................................................................................6.25.3 6-54

System Securing ....................................................................................................6.25.5 6-55

Directional F.S.156.07 Bellcrank (ET) .............................................................................6.29 6-62

Backup Method ......................................................................................................6.29.4 6-63

Defects ..................................................................................................................6.29.2 6-62

Description .............................................................................................................6.29.1 6-62

Primary Method .....................................................................................................6.29.3 6-62

System Securing ....................................................................................................6.29.5 6-63

Directional F.S.159.98 Bellcrank and Bracket (ET) ..........................................................6.30 6-64

Backup Method ......................................................................................................6.30.4 6-65

Defects ..................................................................................................................6.30.2 6-64

Description .............................................................................................................6.30.1 6-64

Primary Method .....................................................................................................6.30.3 6-64

System Securing ....................................................................................................6.30.5 6-65

Directional F.S.164.33 Bellcrank Bracket and Attaching Area

on Deck (ET) ..............................................................................................................6.31 6-66

Backup Method ......................................................................................................6.31.4 6-67

Defects ..................................................................................................................6.31.2 6-66

Description .............................................................................................................6.31.1 6-66

Primary Method .....................................................................................................6.31.3 6-66

System Securing ....................................................................................................6.31.5 6-67

Directional F.S 199.25 Tail Rotor Fitting (ET) ..................................................................6.36 6-77

Backup Method ......................................................................................................6.36.4 6-78

Defects ..................................................................................................................6.36.2 6-77

Description .............................................................................................................6.36.1 6-77

Primary Method .....................................................................................................6.36.3 6-77

System Securing ....................................................................................................6.36.5 6-78

Index 3
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Directional F.S.275 Rotor Control Bracket (ET) ...............................................................6.37 6-79

Backup Method ......................................................................................................6.37.4 6-80

Defects ..................................................................................................................6.37.2 6-79

Description .............................................................................................................6.37.1 6-79

Primary Method .....................................................................................................6.37.3 6-79

System Securing ....................................................................................................6.37.5 6-80

Directional F.S.348 Bellcrank (ET) ..................................................................................6.38 6-81

Backup Method ......................................................................................................6.38.4 6-82

Defects ..................................................................................................................6.38.2 6-81

Description .............................................................................................................6.38.1 6-81

Primary Method .....................................................................................................6.38.3 6-81

System Securing ....................................................................................................6.38.5 6-82

Directional F.S.348 Tail Rotor Bracket (ET) .....................................................................6.39 6-83

Backup Method ......................................................................................................6.39.4 6-84

Defects ..................................................................................................................6.39.2 6-83

Description .............................................................................................................6.39.1 6-83

Primary Method : ...................................................................................................6.39.3 6-83

System Securing ....................................................................................................6.39.5 6-84

Drive Shafts (ET) ..............................................................................................................3.2 3-4

Backup Method ........................................................................................................3.2.4 3-6

Defects ....................................................................................................................3.2.2 3-4

Description ...............................................................................................................3.2.1 3-4

Primary Method .......................................................................................................3.2.3 3-4

System Securing ......................................................................................................3.2.5 3-6

Drive System .......................................................................................................................3 3-1

Drivetrain Couplings (ET) ..................................................................................................3.3 3-7

Backup Method ........................................................................................................3.3.4 3-8

Defects ....................................................................................................................3.3.2 3-7

Description ...............................................................................................................3.3.1 3-7

Primary Method .......................................................................................................3.3.3 3-7

System Securing ......................................................................................................3.3.5 3-8

Drivetrain Flanges (MT) ....................................................................................................3.4 3-8

Backup Method ........................................................................................................3.4.4 3-11

Defects ....................................................................................................................3.4.2 3-8

Description ...............................................................................................................3.4.1 3-8

Primary Method .......................................................................................................3.4.3 3-8

System Securing ......................................................................................................3.4.5 3-11

Droop Stop Ring (MT) .......................................................................................................2.3 2-5

Backup Method ........................................................................................................2.3.4 2-7

Defects ....................................................................................................................2.3.2 2-5

Description ...............................................................................................................2.3.1 2-5

Primary Method .......................................................................................................2.3.3 2-5

System Securing ......................................................................................................2.3.5 2-7

Index 4
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

E

Empennage Frame Assemblies F.S.530 and F.S. 547 and Attached

Stringers (ET) .............................................................................................................4.7 4-18

Backup Method ........................................................................................................4.7.4 4-19

Defects ....................................................................................................................4.7.2 4-18

Description ...............................................................................................................4.7.1 4-18

Primary Method .......................................................................................................4.7.3 4-18

System Securing ......................................................................................................4.7.5 4-19

Engine Access and Ventilation Door Assembly Rig Connecting Link (PT) ........................4.22 4-51

Backup Method ......................................................................................................4.22.4 4-52

Defects ..................................................................................................................4.22.2 4-51

Description .............................................................................................................4.22.1 4-51

Primary Method .....................................................................................................4.22.3 4-51

System Securing ....................................................................................................4.22.5 4-52

Engine Air Inlet 'V" Band Clamp (PT) ................................................................................5.7 5-13

Backup Method ........................................................................................................5.7.4 5-14

Defects ....................................................................................................................5.7.2 5-13

Description ...............................................................................................................5.7.1 5-13

Primary Method .......................................................................................................5.7.3 5-13

System Securing ......................................................................................................5.7.5 5-14

Engine Components (PT) ................................................................................................5.11 5-20

Backup Method ......................................................................................................5.11.4 5-20

Defects ..................................................................................................................5.11.2 5-20

Description .............................................................................................................5.11.1 5-20

Primary Method .....................................................................................................5.11.3 5-20

System Securing ....................................................................................................5.11.5 5-20

Engine Load Demand Spindle Bellcrank Support (ET) .....................................................5.10 5-18

Backup Method ......................................................................................................5.10.4 5-19

Defects ..................................................................................................................5.10.2 5-18

Description .............................................................................................................5.10.1 5-18

Primary Method .....................................................................................................5.10.3 5-18

System Securing ....................................................................................................5.10.5 5-19

Engine Nacelle Strut Attachment Area (ET) ....................................................................4.24 4-55

Backup Method ......................................................................................................4.24.4 4-56

Defects ..................................................................................................................4.24.2 4-55

Description .............................................................................................................4.24.1 4-55

Primary Method .....................................................................................................4.24.3 4-55

System Securing ....................................................................................................4.24.5 4-56

Engine Nose Gearbox (ET) .............................................................................................3.11 3-25

Backup Method ......................................................................................................3.11.4 3-26

Defects ..................................................................................................................3.11.2 3-25

Description .............................................................................................................3.11.1 3-25

Primary Method .....................................................................................................3.11.3 3-25

System Securing ....................................................................................................3.11.5 3-26

Index 5
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Engine Nose Gearbox Input Quill Shaft (MT) ..................................................................3.12 3-26

Backup Method ......................................................................................................3.12.4 3-29

Defects ..................................................................................................................3.12.2 3-26

Description .............................................................................................................3.12.1 3-26

Primary Method .....................................................................................................3.12.3 3-26

System Securing ....................................................................................................3.12.5 3-29

Engine Shroud (PT) ..........................................................................................................5.9 5-16

Backup Method ........................................................................................................5.9.4 5-17

Defects ....................................................................................................................5.9.2 5-16

Description ...............................................................................................................5.9.1 5-16

Primary Method .......................................................................................................5.9.3 5-16

System Securing ......................................................................................................5.9.5 5-17

Engine System .....................................................................................................................5 5-1

Engine Tubing, Couplings, Air Ducts, Fittings, Supports, Brackets, and

Clips (PT) .......................................................................................................................5.5 5-8

Backup Method ........................................................................................................5.5.4 5-10

Defects ....................................................................................................................5.5.2 5-8

Description ...............................................................................................................5.5.1 5-8

Primary Method .......................................................................................................5.5.3 5-10

System Securing ......................................................................................................5.5.5 5-10

Equipment Listing ............................................................................................................ B-1

Exterior Surfaces of all Ferrous Hydraulic Components (Servocylinders,

Actuators, Reservoirs, Etc.) (MT) ................................................................................6.42 6-88

Backup Method ......................................................................................................6.42.4 6-90

Defects ..................................................................................................................6.42.2 6-88

Description .............................................................................................................6.42.1 6-88

Primary Method .....................................................................................................6.42.3 6-89

System Securing ....................................................................................................6.42.5 6-90

F

Ferrous Flight Control System Push-Pull Rods (MT) .......................................................6.19 6-41

Backup Method ......................................................................................................6.19.4 6-43

Defects ..................................................................................................................6.19.2 6-41

Description .............................................................................................................6.19.1 6-41

Primary Method .....................................................................................................6.19.3 6-41

System Securing ....................................................................................................6.19.5 6-43

Fittings, Castings, and Forgings (ET) ................................................................................4.5 4-14

Backup Method ........................................................................................................4.5.4 4-16

Defects ....................................................................................................................4.5.2 4-14

Description ...............................................................................................................4.5.1 4-14

Primary Method .......................................................................................................4.5.3 4-14

System Securing ......................................................................................................4.5.5 4-16

Index 6
TM 1-1520-264-23

INDEX- Continued

Subject Paragraph Page

Number Number

Flight Control Bellcranks (ET) ...........................................................................................6.2 6-5

Backup Method ........................................................................................................6.2.4 6-6

Defects ....................................................................................................................6.2.2 6-5

Description ...............................................................................................................6.2.1 6-5

Primary Method .......................................................................................................6.2.3 6-5

System Securing ......................................................................................................6.2.5 6-6

Flight Control Rods, Connecting Links, Rod Ends, Clevises, Levers, and

Attaching Parts (ET) ...................................................................................................6.10 6-21

Backup Method ......................................................................................................6.10.4 6-22

Defects ..................................................................................................................6.10.2 6-21

Description .............................................................................................................6.10.1 6-21

Primary Method .....................................................................................................6.10.3 6-21

System Securing ....................................................................................................6.10.5 6-22

Flight Control System............................................................................................................6 6-1

Fluid in Honeycomb Core Fuselage Panels, Vertical Fin, etc.(RT) .....................................4.4 4-10

Backup Method.........................................................................................................4.4.4 4-11

Defects ....................................................................................................................4.4.2 4-10

Description ...............................................................................................................4.4.1 4-10

Primary Method .......................................................................................................4.4.3 4-10

System Securing ......................................................................................................4.4.5 4-11

Forward Hanger Bearing Flange (MT) ...............................................................................3.6 3-13

Backup Method ........................................................................................................3.6.4 3-15

Defects ....................................................................................................................3.6.2 3-13

Description ...............................................................................................................3.6.1 3-13

Primary Method .......................................................................................................3.6.3 3-13

System Securing ......................................................................................................3.6.5 3-15

Forward Hanger Bearing Support (ET) ..............................................................................3.7 3-15

Backup Method ........................................................................................................3.7.4 3-17

Defects ....................................................................................................................3.7.2 3-15

Description ...............................................................................................................3.7.1 3-15

Primary Method .......................................................................................................3.7.3 3-15

System Securing ......................................................................................................3.7.5 3-17

Forward Inboard Engine Mount (MT) .................................................................................5.3 5-4

Backup Method ........................................................................................................5.3.4 5-6

Defects ....................................................................................................................5.3.2 5-4

Description ...............................................................................................................5.3.1 5-4

Primary Method .......................................................................................................5.3.3 5-4

System Securing ......................................................................................................5.3.5 5-6

Forward Lower Engine Mount (MT) ...................................................................................5.4 5-6

Backup Method ........................................................................................................5.4.4 5-8

Defects ....................................................................................................................5.4.2 5-6

Description ...............................................................................................................5.4.1 5-6

Primary Method .......................................................................................................5.4.3 5-6

System Securing ......................................................................................................5.4.5 5-8

Index 7
TM 1-1520-264-23

INDEX,- Continued

Subject Paragraph Page

Number Number

Fuselage and Empennage Access Doors, Covers, Panels, Skins, and

Fairings - Metal (ET) .....................................................................................................4.2 4-5

Backup Method ........................................................................................................4.2.4 4-6

Defects ....................................................................................................................4.2.2 4-5

Description ...............................................................................................................4.2.1 4-5

Primary Method .......................................................................................................4.2.3 4-5

System Securing ......................................................................................................4.2.5 4-6

Fuselage Support Holes (ET) ............................................................................................4.8 4-21

Backup Method ........................................................................................................4.8.4 4-22

Defects ....................................................................................................................4.8.2 4-21

Description ...............................................................................................................4.8.1 4-21

Primary Method .......................................................................................................4.8.3 4-21

System Securing ......................................................................................................4.8.5 4-22

G

General Helicopter Attaching Hardware (MT) ..................................................................4.38 4-84

Backup Method ......................................................................................................4.38.4 4-86

Defects ..................................................................................................................4.38.2 4-84

Description .............................................................................................................4.38.1 4-84

Primary Method .....................................................................................................4.38.3 4-84

System Securing ....................................................................................................4.38.5 4-86

General Information ..........................................................................................................1.1 1-2

Airframe Stations .....................................................................................................1.1.9 1-8

Configuration ...........................................................................................................1.1.8 1-8

Description ...............................................................................................................1.1.7 1-6

How to Use This Manual ..........................................................................................1.1.2 1-5

Inspection Item Code ...............................................................................................1.1.3 1-6

Related Publications ................................................................................................1.1.6 1-6

Special Terms, Abbreviations, and Acronyms ..........................................................1.1.1 1-4

Use of NDI Symbols .................................................................................................1.1.4 1-6

Use of Reference Publications .................................................................................1.1.5 1-6

Gun and Ammo Support Mount Pads (ET) ........................................................................4.9 4-22

Backup Method.........................................................................................................4.9.4 4-24

Defects ....................................................................................................................4.9.2 4-22

Description ...............................................................................................................4.9.1 4-22

Primary Method ........................................................................................................4.9.3 4-22

System Securing ......................................................................................................4.9.5 4-24

H

Honeycomb Core Fuselage Panels, Vertical Fin, etc(BT) ..................................................4.3 4-6

Backup Method.........................................................................................................4.3.4 4-10

Defects .....................................................................................................................4.3.2 4-6

Description ...............................................................................................................4.3.1 4-6

Primary Method ........................................................................................................4.3.3 4-8

System Securing.......................................................................................................4.3.5 4-10

Index 8
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Horizontal Stabilator Actuator Fitting (ET) .......................................................................4.21 4-49

Backup Method ......................................................................................................4.21.4 4-51

Defects ..................................................................................................................4.21.2 4-49

Description .............................................................................................................4.21.1 4-49

Primary Method .....................................................................................................4.21.3 4-49

System Securing ....................................................................................................4.21.5 4-51

I

Illustrated Field Manufacture Items List .................................................................................. C-1

Intermediate Gearbox Centrifugal Fan (ET) .....................................................................3.10 3-22

Backup Method ......................................................................................................3.10.4 3-23

Defects ..................................................................................................................3.10.2 3-22

Description .............................................................................................................3.10.1 3-22

Primary Method .....................................................................................................3.10.3 3-22

System Securing ....................................................................................................3.10.5 3-23

Intermediate Gearbox (ET)...............................................................................................3.19 3-42

Backup Method ......................................................................................................3.19.4 3-45

Defects ..................................................................................................................3.19.2 3-42

Description .............................................................................................................3.19.1 3-42

Primary Method .....................................................................................................3.19.3 3-42

System Securing ....................................................................................................3.19.5 3-45

Intermediate Gearbox Flange and Shouldered Shaft (MT) ...............................................3.21 3-48

Backup Method ......................................................................................................3.21.4 3-49

Defects ..................................................................................................................3.21.2 3-48

Description .............................................................................................................3.21.1 3-48

Primary Method .....................................................................................................3.21.3 3-48

System Securing ....................................................................................................3.21.5 3-49

Intermediate Gearbox Retainers (ET) ..............................................................................3.20 3-45

Backup Method ......................................................................................................3.20.4 3-46

Defects ..................................................................................................................3.20.2 3-45

Description .............................................................................................................3.20.1 3-45

Primary Method .....................................................................................................3.20.3 3-45

System Securing ....................................................................................................3.20.5 3-46

Introduction ..........................................................................................................................1 1-1

L

Lateral Feel Spring Cartridge (ET) ...................................................................................6.14 6-29

Backup Method ......................................................................................................6.14.4 6-30

Defects ..................................................................................................................6.14.2 6-29

Description .............................................................................................................6.14.1 6-29

Primary Method .....................................................................................................6.14.3 6-29

System Securing ....................................................................................................6.14.5 6-30

Index 9
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

M

Main Landing Gear Cross Tube Mounting Points (ET) .....................................................4.11 4-27

Backup Method ......................................................................................................4.11.4 4-29

Defects ..................................................................................................................4.11.2 4-27

Description .............................................................................................................4.11.1 4-27

Primary Method .....................................................................................................4.11.3 4-27

System Securing ....................................................................................................4.11.5 4-29

Main Landing Gear Jack Pad Adapter (MT) .....................................................................4.29 4-65

Backup Method ......................................................................................................4.29.4 4-68

Defects ..................................................................................................................4.29.2 4-65

Description .............................................................................................................4.29.1 4-65

Primary Method .....................................................................................................4.29.3 4-65

System Securing ....................................................................................................4.29.5 4-68

Main Landing Gear Lower Structural Support (MT) ..........................................................4.28 4-64

Backup Method ......................................................................................................4.28.4 4-65

Defects ..................................................................................................................4.28.2 4-64

Description .............................................................................................................4.28.1 4-64

Primary Method .....................................................................................................4.28.3 4-64

System Securing.....................................................................................................4.28.5 4-65

Main Landing Gear Shock Strut Housing, Piston, and Rod Ends (MT) .............................4.27 4-62

Backup Method ......................................................................................................4.27.4 4-64

Defects ..................................................................................................................4.27.2 4-62

Description .............................................................................................................4.27.1 4-62

Primary Method .....................................................................................................4.27.3 4-62

System Securing ....................................................................................................4.27.5 4-64

Main Landing Gear Shock Strut Mount Shaft (MT) ..........................................................4.31 4-70

Backup Method ......................................................................................................4.31.4 4-72

Defects ..................................................................................................................4.31.2 4-70

Description .............................................................................................................4.31.1 4-70

Primary Method .....................................................................................................4.31.3 4-70

System Securing ....................................................................................................4.31.5 4-72

Main Landing Gear Shock Strut Support (MT) .................................................................4.10 4-26

Backup Method ......................................................................................................4.10.4 4-27

Defects ..................................................................................................................4.10.2 4-26

Description .............................................................................................................4.10.1 4-26

Primary Method .....................................................................................................4.10.3 4-26

System Securing ....................................................................................................4.10.5 4-27

Main Landing Gear Trailing Arm Cross Tube (MT) ..........................................................4.30 4-68

Backup Method ......................................................................................................4.30.4 4-69

Defects ..................................................................................................................4.30.2 4-68

Description .............................................................................................................4.30.1 4-68

Primary Method ......................................................................................................4.30.3 4-68

System Securing ....................................................................................................4.30.5 4-69

Index 10
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Main Landing Gear Trailing Arms (MT) ............................................................................4.25 4-56

Backup Method ......................................................................................................4.25.4 4-58

Defects ..................................................................................................................4.25.2 4-56

Description .............................................................................................................4.25.1 4-56

Primary Method .....................................................................................................4.25.3 4-56

System Securing ....................................................................................................4.25.5 4-58

Main Landing Gear Wheels (ET)......................................................................................4.26 4-58

Backup Method ......................................................................................................4.26.4 4-61

Defects ...................................................................................................................4.26.2 4-58

Description .............................................................................................................4.26.1 4-58

Primary Method .....................................................................................................4.26.3 4-58

System Securing ....................................................................................................4.26.5 4-61

Main Rotor Blade (PT) ......................................................................................................2.5 2-12

Backup Method ........................................................................................................2.5.4 2-12

Defects ....................................................................................................................2.5.2 2-12

Description ...............................................................................................................2.5.1 2-12

Primary Method .......................................................................................................2.5.3 2-12

System Securing ......................................................................................................2.5.5 2-12

Main Rotor Blade (RT) ......................................................................................................2.6 2-13

Backup Method ........................................................................................................2.6.4 2-17

Defects ....................................................................................................................2.6.2 2-13

Description ...............................................................................................................2.6.1 2-13

Primary Method .......................................................................................................2.6.3 2-13

System Securing ......................................................................................................2.6.5 2-17

Main Rotor Blade (Voids) (BT) ...........................................................................................2.4 2-9

Backup Method ........................................................................................................2.4.4 2-12

Defects ....................................................................................................................2.4.2 2-9

Description ...............................................................................................................2.4.1 2-9

Primary Method .......................................................................................................2.4.3 2-9

System Securing ......................................................................................................2.4.5 2-12

Main Rotor Blade Weight Support Fittings (ET) .................................................................2.7 2-17

Backup Method ........................................................................................................2.7.4 2-19

Defects ......................................................................................................................2.72 2-17

Description ...............................................................................................................2.7.1 2-17

Primary Method .......................................................................................................2.7.3 2-17

System Securing ......................................................................................................2.7.5 2-19

Main Rotor Damper (ET)..................................................................................................2.13 2-30

Backup Method ......................................................................................................2.13.4 2-31

Defects ..................................................................................................................2.13.2 2-30

Description .............................................................................................................2.13.1 2-30

Primary Method .....................................................................................................2.13.3 2-30

System Securing ....................................................................................................2.13.5 2-31

Index 11
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Main Rotor Damper Rod End (MT) ..................................................................................2.15 2-35

Backup Method.......................................................................................................2.15.4 2-37

Defects ..................................................................................................................2.15.2 2-35

Description..............................................................................................................2.15.1 2-35.

Primary Method ......................................................................................................2.15.3 2-35

System Securing ....................................................................................................2.15.5 2-37

Main Rotor Damper Trunnion (ET) ...................................................................................2.14 2-31

Backup Method.......................................................................................................2.14.4 2-35

Defects ..................................................................................................................2.14.2 2-31

Description .............................................................................................................2.14.1 2-31

Primary Method .....................................................................................................2.14.3 2-31

System Securing ....................................................................................................2.14.5 2-35

Main Rotor Droop Stop Follower (Plunger) (PT) ................................................................2.2 2-5

Backup Method ........................................................................................................2.2.4 2-5

Defects .....................................................................................................................2.22 2-5

Description ...............................................................................................................2.2.1 2-5

Primary Method .......................................................................................................2.2.3 2-5

System Securing ......................................................................................................2.2.5 2-5

Main Rotor Feathering Bearing Housing (ET) ..................................................................2.17 2-40

Backup Method ......................................................................................................2.17.4 2-41

Defects ..................................................................................................................2.17.2 2-40

Description .............................................................................................................2.17.1 2-40

Primary Method .....................................................................................................2.17.3 2-40

System Securing ....................................................................................................2.17.5 2-41

Main Rotor Gearshaft Drive Gear Teeth (MT) .................................................................3.17 3-38

Backup Method ......................................................................................................3.17.4 3-40

Defects ..................................................................................................................3.17.2 3-38

Description .............................................................................................................3.17.1 3-38

Primary Method .....................................................................................................3.17.3 3-38

System Securing ....................................................................................................3.17.5 3-40

Main Rotor Head (Hub) (ET) ...........................................................................................2.11 2-25

Backup Method ......................................................................................................2.11.4 2-27

Defects ..................................................................................................................2.11.2 2-25

Description .............................................................................................................2.11.1 2-25

Primary Method . ....................................................................................................2.11.3 2-25

System Securing ....................................................................................................2.11.5 2-27

Main Rotor Head (Hub) (ET) ...........................................................................................3.27 3-62

Description .............................................................................................................3.27.1 3-62

Main Rotor Head Hub Load Plate (MT) ............................................................................2.21 2-49

Backup Method ......................................................................................................2.21.4 2-51

Defects ..................................................................................................................2.21.2 2-49

Description .............................................................................................................2.21.1 2-49

Primary Method ......................................................................................................2.21.3 2-49

System Securing ....................................................................................................2.21.5 2-51

INDEX 12
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Main Rotor Hub Bearing (ET) ...................................................................................................... 2.19 2-45

Backup Method ............................................................................................................ 2.19.4 2-46

Defects ........................................................................................................................ 2.19.2 2-45

Description .................................................................................................................. 2.19.1 2-45

Primary Method ........................................................................................................... 2.19.3 2-45

System Securing ......................................................................................................... 2.19.5 2-46

Main Rotor Hub Brackets (MT) .................................................................................................... 2.22 2-51

Backup Method ............................................................................................................ 2.22.4 2-52

Defects ........................................................................................................................ 2.22.2 2-51

Description ................................................................................................................... 2.22.1 2-51

Primary Method ..................................................................... .......................................2.22.3 2-51

System Securing ................................................................... .......................................2.22.5 2-52

Main Rotor Hub Lower Plate (MT) ................................................................................................ 2.23 2-52

Backup Method .................................................................... ........................................2.23.4 2-54

Defects ....................................................................................... .................................2.23.2 2-52

Description ..................................................................... ..............................................2.23.1 2-52

Primary Method .. ......................................................................................................... 2.23.3 2-52

System Securing ......................................................................................................... 2.23.5 2-54

Main Rotor Hub Retention Nut (MT) ............................................................................................ 2.10 2-23

Backup Method ............................................................................................................ 2.10.4 2-25

Defects ........................................................................................................................ 2.10.2 2-23

Description .................................................................................................................. 2.10.1 2-23

Primary Method ........................................................................................................... 2.10.3 2-23

System Securing ......................................................................................................... 2.10.5 2-25

Main Rotor Lead Lag Link (Damper Link) (ET) ............................................................................ 2.12 2-27

Primary Method ........................................................................................................... 2.12.3 2-27

Backup Method ............................................................................................................ 2.12.4 2-28

Defects ........................................................................................................................ 2.12.2 2-27

Description .................................................................................................................. 2.12.1 2-27

System Securing ......................................................................................................... 2.12.5 2-28

Main Rotor Link Barrels (MT) ........................................................................................................ 6.4 6-9

Backup Method .............................................................................................................. 6.4.4 6-10

Defects .......................................................................................................................... 6.4.2 6-9

Description ................ ...................................................................... ..............................6.4.1 6-9

Primary Method ............................................................................................................. 6.4.3 6-9

System Securing ......................................................................................................... 6.4.5 6-10

Main Rotor Lower Shoe (ET) ....................................................................................................... 2.20 2-46

Backup Method ............................................................................................................ 2.20.4 2-48

Defects ........................................................................................................................ 2.20.2 2-46

Description .................................................................................................................. 2.20.1 2-46

Primary Method .................................................................................. .........................2.20.3 2-46

System Securing ......................................................................................................... 2.20.5 2-48

Index 13
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Main Rotor Mast (MT) ................................................................................................................... 2.8 2-19

Backup Method .............................................................................................................. 2.8.4 2-20

Defects .......................................................................................................................... 2.8.2 2-19

Description .................................................................................................................... 2.8.1 2-19

Primary Method ............................................................................................................. 2.8.3 2-19

System Securing ........................................................................................................... 2.8.5 2-20

Main Rotor Mast Retaining Ring (MT) ........................................................................................... 2.9 2-20

Backup Method .............................................................................................................. 2.9.4 2-23

Defects .......................................................................................................................... 2.9.2 2-20

Description .................................................................................................................... 2.9.1 2-20

Primary Method ............................................................................................................. 2.9.3 2-20

System Securing ........................................................................................................... 2.9.5 2-23

Main Rotor Mast Support Base (ET) ............................................................................................ 3.18 3-40

Backup Method ............................................................................................................ 3.18.4 3-42

Defects ........................................................................................................................ 3.18.2 3-40

Description .................................................................................................................. 3.18.1 3-40

Primary Method ........................................................................................................... 3.18.3 3-40

System Securing ......................................................................................................... 3.18.5 3-42

Main Rotor Pitch Housing (ET) .................................................................................................... 2.16 2-37

Backup Method ............................................................................................................ 2.16.4 2-38

Defects ........................................................................................................................ 2.16.2 2-37

Description .................................................................................................................. 2.16.1 2-37

Primary Method ........................................................................................................... 2.16.3 2-37

System Securing ......................................................................................................... 2.16.5 2-38

Main Rotor Scissors Lower Arm (ET) ............................................................................................ 6.6 6-13

Backup Method ............................................................................................................ 6.6.4 6-14

Defects .......................................................................................................................... 6.6.2 6-13

Description .................................................................................................................... .6.6.1 6-13

Primary Method ............................................................................................................. 6.6.3 6-13

System Securing ........................................................................................................... 6.6.5 6-14

Main Rotor Scissors Upper Arm (ET) ............................................................................................ 6.5 6-11

Backup Method .............................................................................................................. 6.5.4 6-12

Defects .......................................................................................................................... 6.5.2 6-11

Description ......................................................................... ............................................6.5.1 6-11

Primary Method .............................................................................................................. 6.5.3 6-11

System Securing ........................................................................................................... 6.5.5 6-12

Main Rotor Striker Plate and Shims (MT) ................................................................................... 2.18 2-41

Backup Method ......................................................................................................... 2.18.4 2-43

Defects ........................................................................................................................ 2.18.2 2-41

Description ........................................................................ ...........................................2.18.1 2-41

Primary Method ..................................................................... .......................................2.18.3 2-41

System Securing ................................................................... .......................................2.18.5 2-43

Main Rotor Support Mast (MT) .................................................................................................... 3.28 3-62

Description .................................................................................................................. 3.28.1 3-62

Index 14
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Main Rotor Swashplate Shoulder Pin Mating Bores (ET) ............................................................... 6.3 6-6

Backup Method ............................................................................................................. 6.3.4 6-9

Defects ........................................................................................................................... 6.3.2 6-6

Description .................................................................................................................... 6.3.1 6-6

Primary Method ............................................................................................................. 6.3.3 6-6

System Securing ........................................................................................................... 6.3.5 6-9

Maintenance Allocation Chart ...................................................................................................... ....... A-1

Main Transmission APU Drive Flange (MT) ................................................................................ 3.15 3-33

Backup Method .......................................................................................................... 3.15.4 3-36

Defects ........................................................................................................................ 3.15.2 3-33

Description .................................................................................................................. 3.15.1 3-33

Primary Method ........................................................................................................... 3.15.3 3-33

System Securing ....................................................................................................... 3.15.5 3-36

Main Transmission Compressor Drive Adapter (ET) .................................................................... 3.14 3-32

Backup Method ............................................................................................................ 3.14.4 3-33

Defects ........................................................................................................................ 3.14.2 3-32

Description .................................................................................................................. 3.14.1 3-32

Primary Method ........................................................................................................... 3.14.3 3-32

System Securing ......................................................................................................... 3.14.5 3-33

Main Transmission (ET) ............................................................................................................ 3.13 3-29

Backup Method ............................................................................................................ 3.13.4 3-32

Defects ........................................................................................................................ 3.13.2 3-29

Description .................................................................................................................. 3.13.1 3-29

Primary Method ........................................................................................................... 3.13.3 3-29

System Securing ......................................................................................................... 3.13.5 3-32

Main Transmission Tail Rotor Drive Flange (MT) ...................................................................... 3.16 3-36

Backup Method ............................................................................................................ 3.16.4 3-37

Defects ........................................................................................................................ 3.16.2 3-36

Description ................................................................................................................ 3.16.1 3-36

Primary Method ........................................................................................................... 3.16.3 3-36

System Securing ......................................................................................................... 3.16.5 3-38

Marking and/or Recording of Inspection Results ............................................................... 1.3 1-21

N

Nacelle Carry-Through Post Assembly (ET) .............................................................................. 4.15 4-35

Backup Method ............................................................................................................ 4.15.4 4-38

Defects ...................................................................................................................... 4.15.2 4-35

Description .................................................................................................................. 4.15.1 4-35

Primary Method ........................................................................................................... 4.15.3 4-35

System Securing ......................................................................................................... 4.15.5 4-38

Nondestructive Inspection Methods ................................................................................ 1.4 1-22

Acceptance/Rejection Criteria .................................................................................... 1.4.13 1-41

Bond Testing (BT) Method ........................................................................................... 1.4.6 1-24

Demagnetization of Inspection Parts ............................................................................ 1.4.9 1-34

Eddy Current (ET) Method ......................................................................................... 1.4.11 1-36

Equipment Used for NDI ............................................................................................ 1.4.14 1-40

Fluorescent Penetrant (PT) Method ............................................................................. 1.4.7 1-26

Index 15
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Magnetic Particle (MT) Method ...................................................................................... 1.4.8 1-32

Materials Used for NDI ................................................................................................ 1.4.15 1-40

NDI General Safety Precautions .................................................................................. 1.4.5 1-24

Post Cleaning and Restoration of Part or Area After NDI ........................................... 1.4:16 1-40

Preparation of Helicopter for NDI ................................................................................. 1.4.3 1-23

Preparation of Part or Area for NDI .............................................................................. 1.4.4 1-23

Purpose of Nondestructive Inspection (NDI) ................................................................ 1.4.1 1-22

Radiographic (RT) Method ......................................................................................... 1.4.10 1-35

Selecting the NDI Method ............................................................................................ 1.4.2 1-23

Ultrasonic (UT) Method ................................................................................................ 1.4.12 1-38

Nonferrous Flight Control System Push-Pull Rods (ET) ............................................................. 6.20 6-43

Backup Method ............................................................................................................ 6.20.4 6-44

Defects ........................................................................................................................ 6.20.2 6-43

Description .................................................................................................................. 6.20.1 6-43

Primary Method ......................................................................................................... 6.20.3 6-43

System Securing ......................................................................................................... 6.20.5 6-44

P

Pilot Collective Stick Cylinder (ET) ........................................................................................... . 6.9 6-19

Backup Method ............................................................................................................ 6.9.4 6-20

Defects ........................................................................................................................ 6.9.2 6-19

Description .................................................................................................................. 6.9.1 6-19

Primary Method ............................................................................................................. 6.9.3 6-19

System Securing ......................................................................................................... 6.9.5 6-20

Pilot Collective Stick Support Assembly (ET) ............................................................................ 6.11 6-22

Backup Method .......................................................................................................... 6.11.4 6-24

Defects ........................................................................................................................ 6.11.2 6-22

Description ................................................................................................................ 6.11.1 6-22

Primary Method ........................................................... ............................................... 6.11.3 6-22

System Securing ................................................................. ....................................... 6.11.5 6-24

Pilot CPG Collective Stick Rotor Housing (ET) ............................................................................ 6.8 6-17

Backup Method .............................................................................................................. 6.8.4 6-18

Defects .......................................................................................................................... 6.8.2 6-17

Description ............................................................................................................... 6.8.1 6-17

Primary Method .......................................................................................................... 6.8.3 6-17

System Securing ........................................................................................................... 6.8.5 6-18

Pilot CPG Collective Stick Tube (ET) .......................................................................................... 6.7 6-15

Backup Method .............................................................................................................. 6.7.4 6-16

Defects .......................................................................................................................... 6.7.2 6-15

Description .................................................................................................................. 6.7.1 6-15

Primary Method ............................................................ ................................................ 6.7.3 6-15

System Securing .................................................................... ........................................6.7.5 6-16

Index 16
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Pilot/CPG Directional Control Pedal Release Handle (ET) ......................................................... 6.33 6-69

Backup Method ............................................................................................................ 6.33.4 6-71

Defects ........................................................................................................................ 6.33.2 6-69

Description .... .......................................................................................................... 6.33.1 6-69

Primary Method ........................................................................................................... 6.33.3 6-69

System Securing ......................................................................................................... 6.33.5 6-71

Pilot/CPG Directional Control Pedal Release Nuts (MT- ............................................................ 6.35 6-75

Backup Method .......................................................................................................... 6.35.4 6-76

Defects ...................................................................................................................... 6.35.2 6-75

Description .................................................................................................................. 6.35.1 6-75

Primary Method ........................................................................................................... 6.35.3 6-75

System Securing ......................................................................................................... 6.35.5 6-76

Pilot/CPG Directional Control Pedal Release Shaft (MT) ........................................................... 6.34 6-73

Backup Method ......................................................................................................... 6.34.4 6-75

Defects ......... ........................................................................................................... 6.34.2 6-73

Description ................................................................................................................ 6.34.1 6-73

Primary Method ......................................................................................................... 6.34.3 6-73

System Securing ....................................................................................................... 6.34.5 6-75

Pilot Cyclic Stick (ET) ............................................................................................................... 6.13 6-27

Backup Method .......................................................................................................... 6.13.4 6-28

Defects ...................................................................................................................... 6.13.2 6-27

Description ................................................................................................................ 6.13.1 6-27

Primary Method ........................................................................................................... 6.13.3 6-27

System Securing ......................................................................................................... 6.13.5 6-28

Pilot Cyclic Stick Housing and Support Assembly (ET) .............................................................. 6.15 6-31

Backup Method .......................................................................................................... 6.15.4 6-32

Defects ...................................................................................................................... 6.15.2 6-31

Description .................................................................................................................. 6.15.1 6-31

Primary Method ........................................................................................................... 6.15.3 6-31

System Securing ....................................................................................................... 6.15.5 6-32

Pilot Directional Shear Pin Activated Decoupler (SPAD) Bellcranks (ET) .................................. 6.28 6-60

Backup Method ............................................................................................................ 6.28.4 6-61

Defects ...................................................................................................................... 6.28.2 6-60

Description .................................................................................................................. 6.28.1 6-60

Primary Method ............................................................. ...............................................6.28.3 6-60

System Securing ............................................................ ..............................................6.28.5 6-61

Pilot Directional Shear Pin Activated Decoupler (SPAD) Remote

Control Lever (ET) .............................................................................................................. 6.27 6-58

Backup Method .......................................................................................................... 6.27.4 6-59

Defects ...................................................................................................................... 6.27.2 6-58

Description .................................................................................................................. 6.27.1 6-58

Primary Method ........................................................................................................... 6.27.3 6-58

System Securing ....................................................................................................... 6.27.5 6-59

Index I7
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Pilot Directional Shear Pin Activated Decoupler (SPAD)

Transducer Arm (ET) .......................................................................................................... 6.26 6-56

Backup Method ............................................................................................................ 6.26.4 6-57

Defects ........................................................................................................................ 6.26.2 6-56

Description .................................................................................................................. 6.26.1 6-56

Primary Method ........................................................................................................... 6.26.3 6-56

System Securing ..................................................................................................... 6.26.5 6-57

Pilot Longitudinal Shear Pin Activated Decoupler (SPAD) Outer and

Inner Lever (ET) ................................................................................................................. 6.32 6-68

Backup Method ............................................................................................................ 6.32.4 6-69

Defects ........................................................................................................................ 6.32.2 6-68

Description .................................................................................................................. 6.32.1 6-68

Primary Method ........... .................................................................... ............................6.32.3 6-68

System Securing ........... ................................................................... ...........................6.32.5 6-69

R

Rotor Mixer Support Assembly Bolt (MT) ................................................................................... 4.13 4-32

Backup Method .......................................................................................................... 4.13.4 4-33

Defects ........................................................................................................................ 4.13.2 4-32

Description .................................................................................................................. 4.13.1 4-32

Primary Method ........................................................................................................... 4.13.3 4-32

System Securing ...................................................................................................... 4.13.5 4-33

Backup Method ............................................................................................................ 4.12.4 4-32

Defects ....................................................................................................................... 4.12.2 4-29

Description ................................................................................................................ 4.12.1 4-29

Primary Method ........................................................................................................... 4.12.3 4-29

System Securing ......................................................................................................... 4.12.5 4-32

Rotor System ................................................................................................................................... 2 2-1

S

Starter Flange (ET) ..................................................................................................................... 5.8 5-14

Backup Method .............................................................................................................. 5.8.4 5-16

Defects .......................................................................................................................... 5.8.2 5-14

Description .................................................................................................................... 5.8.1 5-14

Primary Method ............................................................................................................. 5.8.3 5-14

System Securing ........................................................................................................... 5.8.5 5-16

T

TADS/PNVS Support Fitting (ET) .............................................................................................. 4.18 4-44

Backup Method ............................................................................................................ 4.18.4 4-45

Defects ........................................................................................................................ 4.18.2 4-44

Description .................................................................................................................. 4.18.1 4-44

Primary Method ........................................................................................................... 4.18.3 4-44

System Securing ......................................................................................................... 4.18.5 4-46

Index 18
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Tail Landing Gear Actuating Cylinder Assembly (ET) ................................................................ 4.36 4-79

Backup Method .......................................................................................................... 4.36.4 4-81

Defects ........................................................................................................................ 4.36.2 4-79

Description ................................................................................................................ 4.36.1 4-79

Primary Method ......................................................................................................... 4.36.3 4-79

System Securing ....................................................................................................... 4.36.5 4-81

Tail Landing Gear Fork (ET) ...................................................................................................... 4.32 4-72

Backup Method .......................................................................................................... 4.32.4 4-74

Defects ...................................................................................................................... 4.32.2 4-72

Description ................................................................................................................ 4.32.1 4-72

Primary Method ......................................................................................................... 4.32.3 4-72

System Securing ....................................................................................................... 4.32.5 4-74

Tail Landing Gear Shock Strut (MT) .......................................................................................... 4.34 4-76

Backup Method ............................................................................................................ 4.34.4 4-77

Defects ........................................................................................................................ 4.34.2 4-76

Description ................................................................................................................ 4.34.1 4-76

Primary Method ........................................................................................................... 4.34.3 4-76

System Securing ......................................................................................................... 4.34.5 4-77

Tail Landing Gear Trailing Arms (ET) ........................................................................................ 4.35 4-78

Backup Method ............................................................................................................ 4.35.4 4-79

Defects ........................................................................................................................ 4.35.2 4-78

Description ................................................................................................................. 4.35.1 4-78

Primary Method ........................................................................................................... 4.35.3 4-78

System Securing ......................................................................................................... 4.35.5 4-79

Tail Rotor Blade (PT) ................................................................................................................ 2.25 2-57

Backup Method .......................................................................................................... 2.25.4 2-58

Defects ...................................................................................................................... 2.25.2 2-57

Description ................................................................................................................ 2.25.1 2-57

Primary Method ......................................................................................................... 2.25.3 2-57

System Securing ....................................................................................................... 2.25.5 2-58

Tail Rotor Blades (Fluid) (RT) ................................................................................................... 2.27 2-61

Backup Method ............................................................................................................ 2.27.4 2-62

Defects ...................................................................................................................... 2.27.2 2-61

Description ................................................................................................................ 2.27.1 2-61

Primary Method ......................................................................................................... 2.27.3 2-61

System Securing ....................................................................................................... 2.27.5 2-62

Tail Rotor Blade (Voids) (BT) .................................................................................................... 2.26 2-58

Backup Method .......................................................................................................... 2.26.4 2-61

Defects ...................................................................................................................... 2.26.2 2-58

Description ................................................................................................................ 2.26.1 2-58

Primary Method ......................................................................................................... 2.26.3 2-58

System Securing ....................................................................................................... 2.26.5 2-61

Index 19
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Tail Rotor Clamps and Locking Plates (ET) ............................................................................... 2.29 2-66

Backup Method ........................................................................................................... 2.29.4. 2-69

Defects ........................................................................................................................ 2.29.2 2-66

Description .................................................................................................................. 2.29.1 2-66

Primary Method ........................................................................................................... 2.29.3 2-66

System Securing ......................................................................................................... 2.29.5 2-69

Tail Rotor Drive Links (ET) ........................................................................................................ 6.41 6-86

Backup Method ............................................................................................................ 6.41.4 6-88

Defects ...................................................................................................................... 6.41.2 6-86

Description .................................................................................................................. 6.41.1 6-86

Primary Method ........................................................................................................... 6.41.3 6-86

System Securing ....................................................................................................... 6.41.5 6-88

Tail Rotor Fork Assembly (Head and Teeter Stop) (ET) ............................................................. 2.24 2-54

Backup Method .......................................................................................................... 2.24.4 2-55

Defects ...................................................................................................................... 2.24.2 2-54

Description ................................................................................................................ 2.24.1 2-54

Primary Method ........................................................................................................... 2.24.3 2-54

System Securing ......................................................................................................... 2.24.5 2-55

Tail Rotor Gearbox (ET) ............................................................................................................ 3.22 3-49

Backup Method ............................................................................................................ 3.22.4 3-51

Defects ...................................................................................................................... 3.22.2 3-49

Description .................................................................................................................. 3.22.1 3-49

Primary Method ........................................................................................................... 3.22.3 3-50

System Securing ......................................................................................................... 3.22.5 3-51

Tail Rotor Gearbox Forward and Aft Strut (MT) ......................................................................... 3.25 3-56

Backup Method .......................................................................................................... 3.25.4 3-59

Defects ........................................................................................................................ 3.25.2 3-56

Description .................................................................................................................. 3.25.1 3-56

Primary Method ......................................................................................................... 3.25.3 3-56

System Securing ......................................................................................................... 3.25.5 3-59

Tail Rotor Gearbox Forward and Aft Strut Fittings (MT) ............................................................. 3.26 3-59

Backup Method .......................................................................................................... 3.26.4 3-60

Defects ...................................................................................................................... 3.26.2 3-59

Description .................................................................................................................. 3.26.1 3-59

Primary Method ......................................................................................................... 3.26.3 3-59

System Securing ......................................................................................................... 3.26.5 3-60

Tail Rotor Gearbox Retainers (ET) ............................................................................................ 3.24 3-54

Backup Method ............................................................................................................ 3.24.4 3-56

Defects ...................................................................................................................... 3.24.2 3-54

Description .................................................................................................................. 3.24.1 3-54

Primary Method .......................................................................................................... 3.24.3 3-54

System Securing ......................................................................................................... 3.24.5 3-56

Index 20
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

Tail Rotor Gearbox Shouldered Shaft (MT) .................................................................................. 3.23 3-51

Backup Method ............................................................................................................ 3.23.4 3-54

Defects ........................................................................................................................ 3.23.2 3-51

Description .................................................................................................................. 3.23.1 3-51

Primary Method .......................................................................................................... 3.23.3. 3-51

System Securing ......................................................................................................... 3.23.5 3-54

Tail Rotor Hub (ET) ........................................................................................................ 2.28 2-65

Backup Method ............................................................................................................ 2.28.4 2-66

Defects ........................................................................................................................ 2.28.2 2-65

Description .................................................................................................................. 2.28.1 2-65

Primary Method ........................................................................................................... 2.28.3 2-65

System Securing ......................................................................................................... 2.28.5 2-66

Tail Rotor Swashplate Control Bellcrank (MT) ............................................................................. 6.40 6-85

Backup Method ............................................................................................................ 6.40.4 6-86

Defects ........................................................................................................................ 6.40.2 6-85

Description .................................................................................................................. 6.40.1 6-85

Primary Method ........................................................................................................... 6.40.3 6-85

System Securing ......................................................................................................... 6.40.5 6-86

Tail Wheel (ET) ........................................................................................................................... 4.33 4-74

Backup Method ............................................................................................................ 4.33.4 4-76

Defects ........................................................................................................................ 4.33.2 4-74

Description .................................................................................................................. 4.33.1 4-74

Primary Method ........................................................................................................... 4.33.3 4-74

System Securing ......................................................................................................... 4.33.5 4-76

Transmission Deck (ET) ................................................................................................................ 4.6 4-16.

Backup Method .............................................................................................................. 4.6.4 4-18

Defects .......................................................................................................................... 4.6.2 4-16

Description .................................................................................................................... 4.6.1 4-16

Primary Method ............................................................................................................. 4.6.3 4-16

System Securing ........................................................................................................... 4.6.5 4-18

Transmission Rotor Support Strut Assemblies (ET) ..................................................................... 4.14 4-34

Backup Method ............................................................................................................ 4.14.4 4-35.

Defects ........................................................................................................................ 4.14.2 4-34

Description .................................................................................................................. 4.14.1 4-34

Primary Method ........................................................................................................... 4.14.3 4-34

System'Securing .......................................................................................................... 4.14.5 4-35

Type of Construction ..................................................................................................................... 1.2 1-8

Access Provisions........................................................................................................... 1.2.6 1-13

Airframe and Landing Gear System................................................................................ 1.2.3 1-12

Drive System ................................................................................................................. 1.2.2 1-12

Engine System .............................................................................................................. 1.2.4 1-13

Flight Control System .................................................................................................... 1.2.5 1-13

Rotor System ................................................................................................................. 1.2.1 1-8

Steps, Handholds, and Walkways .................................................................................. 1.2.7 1-13

Index 21
TM 1-1520-264-23

INDEX - Continued

Subject Paragraph Page

Number Number

V

Vertical Stabilizer Barrel Nuts (MT) ............................................................................................. 4.20 4-48

Backup Method ............................................................................................................ 4.20.4 4-49

Defects ........................................................................................................................ 4.20.2 4-48

Description ................................................................................................................... 4.20.1 4-48

Primary Method ........................................................................................................... 4.20.3 4-48

System Securing ......................................................................................................... 4.20.5 4-49

Vertical Stabilizer Lugs (ET) ........................................................................................................ 4.19 4-46

Backup Method ............................................................................................................ 4.19.4 4-48

Defects ........................................................................................................................ 4.19.2 4-46

Description .................................................................................................................. 4.19.1 4-46

Primary Method ........................................................................................................... 4.19.3 4-46

System Securing ......................................................................................................... 4.19.5 4-48

W

Wing Attachment Fittings on Wing and Fuselage (ET) ................................................................ 4.16 4-38

Backup Method ............................................................................................................ 4.16.4 4-40

Defects ........................................................................................................................ 4.16.2 4-38

Description .................................................................................................................. 4.16.1 4-38

Primary Method ........................................................................................................... 4.16.3 4-38

System Securing ......................................................................................................... 4.16.5 4-40

Wing Rack Attachment Points/Mounts (ET) ................................................................................. 4.17 4-41

Backup Method ............................................................................................................ 4.17.4 4-44

Defects ........................................................................................................................ 4.17.2 4-41

Description .................................................................................................................. 4.17.1 4-41

Primary Method ........................................................................................................... 4.17.3 4-41

System Securing ......................................................................................................... 4.17.5 4-44

Index 22
TM 1-1520-264-23

These are the instructions for sending an electronic 2028

The following format must be used if submitting an electronic 2028. The subject line must be exactly the same and all

fields must be included; however only the following fields are mandatory: 1, 3, 4, 5, 6, 7, 8, 9, 10, 13, 15, 16, 17, and 27.

From: "Whomever" <whomever@avma27.army.mil>

To: mpmt%avma28@st-louis-emh7.army.mil

Subject: DA Form 2028

1. From: Joe Smith

2. Unit: home

3. Address: 4300 Park

4. City: Hometown

5. St: MO

6. Zip: 77777

7. Date Sent: 19-OCT-93

8. Pub no: 55-2840-229-23

9. Pub Title: TM

'10. Publication Date: 04-JUL-85

11. Change Number: 7

12. Submitter Rank: MSG

13. Submitter FName: Joe

14. Submitter MName: T

15. Submitter LName: Smith

16. Submitter Phone: 123-123-1234

17. Problem:1

18. Page: 2

19. Paragraph: 3

20. Line: 4

21. NSN: 5

22. Reference: 6

23. Figure: 7

24. Table: 8

25. Item: 9

26. Total: 123

27. Text:

This is the text for the problem below line 27.

SOMETHING WRONG

FIGURE

15 May 1996

P.S.- - IF YOUR OUTFIT WANTS TO KNOW ABOUT YOUR

RECOMMENDATION, MAKE A CARBON COPY OF THIS

AND GIVE TO YOUR HEADQUARTERS.

PAGE PARARECOMMENDED CHANGES TO EQUIPMENT TECHNICAL PUBLICATIONS

WITH THIS PUBLICATION?

FROM: (PRINT YOUR UNIT’S COMPLETE ADDRESS)

DATE SENT

PUBLICATION NUMBER PUBLICATION DATE PUBLICATION TITLE

BE EXACT PIN--POINT WHERE IT IS

NO GRAPH NO

TABLE

NO

IN THIS SPACE, TELL WHAT IS WRONG

AND WHAT SHOULD BE DONE ABOUT IT:

PRINTED NAME, GRADE OR TITLE, AND TELEPHONE NUMBER SIGN HERE

DA 2028--2 FORM

1 JUL 79

PREVIOUS EDITIONS

ARE OBSOLETE.

DRSTS-M verprint2, 1 Nov 80

THEN . .JOT DOWN THE

DOPE ABOUT IT ON THIS

FORM, CAREFULLY TEAR

IT OUT, FOLD IT AND

DROP IT IN THE MAIL!

TM 55-1520-210-PM Phased Maintenance Checklist, UH-1H/V 

and EH-1H/X Aircraft
FILL IN YOUR

UNITS ADDRESS

OFFICIAL BUSINESS

TEAR ALO

NG PE

RFO

R

A

TED LINE

Commander

USAAMCOM

ATTN: AMSAM-MMC-LS-LP

Redstone Arsenal, AL 35898-5230

REVERSE OF DA FORM 2028-2

FOLD BACK

DEPARTMENT OF THE ARMY
PARA- FIGURE

THEN . .JOT DOWN THE

DOPE ABOUT IT ON THIS

FORM, CAREFULLYTEAR

IT OUT, FOLD IT AND

DROP IT IN THE MAIL!

P.S.- - IF YOUR OUTFIT WANTS TO KNOW ABOUT YOUR

RECOMMENDATION, MAKE A CARBON COPY OF THIS

AND GIVE TO YOUR HEADQUARTERS.

PAGE

RECOMMENDED CHANGES TO EQUIPMENT TECHNICAL PUBLICATIONS

WITH THIS PUBLICATION?

FROM: (PRINT YOUR UNIT’S COMPLETE ADDRESS)

DATE SENT

PUBLICATION NUMBER PUBLICATION DATE PUBLICATION TITLE

BE EXACT PIN--POINT WHERE IT IS

NO GRAPH NO

TABLE

NO

IN THIS SPACE, TELL WHAT IS WRONG

AND WHAT SHOULD BE DONE ABOUT IT:

PRINTED NAME, GRADE OR TITLE, AND TELEPHONE NUMBER SIGN HERE

DA 2028--2 FORM

1 JUL 79

PREVIOUS EDITIONS

ARE OBSOLETE.

DRSTS-M verprint2, 1 Nov 80

SOMETHING WRONG
FILL IN YOUR

UNITS ADDRESS

OFFICIAL BUSINESS

TEAR ALO

NG PE

RFO

R

A

TED LINE

Commander

USAAMCOM

ATTN: AMSAM-MMC-LS-LP

Redstone Arsenal, AL 35898-5230

REVERSE OF DA FORM 2028-2

FOLD BACK

DEPARTMENT OF THE ARMY
The Metric System and Equivalents

Linear Measure Liquid Measure

1 centiliter = 10 milliters = .34 fl. ounce

1 centimeter = 10 millimeters = .39 inch 1 deciliter = 10 centiliters = 3.38 fl. ounces

1 decimeter = 10 centimeters = 3.94 inches 1 liter = 10 deciliters = 33.81 fl. ounces

1 meter = 10 decimeters = 39.37 inches 1 dekaliter = 10 liters = 2.64 gallons

1 dekameter = 10 meters = 32.8 feet 1 hectoliter = 10 dekaliters = 26.42 gallons

1 hectometer = 10 dekameters = 328.08 feet 1 kiloliter = 10 hectoliters = 264.18 gallons

1 kilometer = 10 hectometers = 3,280.8 feet

Square Measure

Weights

1 sq. centimeter = 100 sq. millimeters = .155 sq. inch

1 centigram = 10 milligrams = .15 grain 1 sq. decimeter = 100 sq. centimeters = 15.5 sq. inches

1 decigram = 10 centigrams = 1.54 grains 1 sq. meter (centare) = 100 sq. decimeters = 10.76 sq. feet

1 gram = 10 decigram = .035 ounce 1 sq. dekameter (are) = 100 sq. meters = 1,076.4 sq. feet

1 decagram = 10 grams = .35 ounce 1 sq. hectometer (hectare) = 100 sq. dekameters = 2.47 acres

1 hectogram = 10 decagrams = 3.52 ounces 1 sq. kilometer = 100 sq. hectometers = .386 sq. mile

1 kilogram = 10 hectograms = 2.2 pounds

1 quintal = 100 kilograms = 220.46 pounds Cubic Measure

1 metric ton = 10 quintals = 1.1 short tons

1 cu. centimeter = 1000 cu. millimeters = .06 cu. inch

1 cu. decimeter = 1000 cu. centimeters = 61.02 cu. inches

1 cu. meter = 1000 cu. decimeters = 35.31 cu. feet

Approximate Conversion Factors

To change To Multiply by To change To Multiply by

inches centimeters 2.540 ounce-inches Newton-meters .007062

feet meters .305 centimeters inches .394

yards meters .914 meters feet 3.280

miles kilometers 1.609 meters yards 1.094

square inches square centimeters 6.451 kilometers miles .621

square feet square meters .093 square centimeters square inches .155

square yards square meters .836 square meters square feet 10.764

square miles square kilometers 2.590 square meters square yards 1.196

acres square hectometers .405 square kilometers square miles .386

cubic feet cubic meters .028 square hectometers acres 2.471

cubic yards cubic meters .765 cubic meters cubic feet 35.315

fluid ounces milliliters 29.573 cubic meters cubic yards 1.308

pints liters .473 milliliters fluid ounces .034

quarts liters .946 liters pints 2.113

gallons liters 3.785 liters quarts 1.057

ounces grams 28.349 liters gallons .264

pounds kilograms .454 grams ounces .035

short tons metric tons .907 kilograms pounds 2.205

pound-feet Newton-meters 1.356 metric tons short tons 1.102

pound-inches Newton-meters .11296

Temperature (Exact)

°F Fahrenheit 5/9 (after Celsius °C

temperature subtracting 32) temperature
PIN: 075201-001