m/q&773 

AC NO: AC 20-64 

DATE: 8/l/69 

‘ADVISORY 

CIRCULAR 

DEPARTMENT OF TRANSPORTATION 

FEDERAL AVIATION ADMINISTRATION 

SUBJECT: MAINTENANCE INSPECTION NOTES FOR LOCKHEED L-188 

SERIES AIRCRAFT 

1. PURPOSE. This handbook describes maintenance inspection notes which can 

be used for the maintenance support of certain structural parts of ' 

Lockheed L-188 series aircraft. This is one of a series of Advisory 

Circulars to be published on existing aircraft to assist maintenance 

personnel in directing their attention to those areas which, in 

addition to normal maintenance practices, have been shown to require 

special attention. 

2. DESCRIPTION. Maintenance on the wing, fuselage, empennage, flight 

controls, and landing gear structure is reviewed with a view toward 

supplementing information currently available. 

3. HOW TO GET THIS PUBLICATION. 

a. Order additional copies of this publication from: 

Department of Transportation 

Federal Aviation Administration 

Distribution Unit, TAD-484.3 

Washington, D. C. 20590 

b. Identify this publication as: Advisory Circular 20-64 

Maintenance Inspection Notes for Lockheed L-188 Series Aircraft. 

Flight Standards Service 

Initiated by: AC-230/FS-320 
AC 20-64 

8/l/69 

TABLE OF CONTEXVI'S 

Page No. 

cmE.R 1. MAINTENANCE INSPECTICN NOTES. 

1. 

2, 

30 

4. 

5* 

6. 

7* 

8. 

9. 

10. 

Introduction. 1 

Description. 1 

Background. 1 

General Information. 1 

Type of Construction. 2 

General Visual Inspection Tips. 3 

Nondestructive Testing (NIYT). 3 

Aircraft Station Diagrams. 4 

Definitions. 4 

Abbreviations Used In This Document. 4 

CHAFTER 2. WING. 5 

11. L-188 Aircraft Maintenance Information. 5 

CHAPTER 3. FUSELAGE. 

12. L-188 Aircraft Maintenance Information. 

cmER 4. FLIGHT CONTROLS. 11 

13* L-188 Aircraft Maintenance Information. 11 

CHAPPER 5.LANDING GEAR. 

14. L-188 Aircraft Maintenance Information. 13 

cmm 6. CORROSION PRONE AREAS. 15 

15. 

16. 

17. 

18. 

19. 

20. 

21. 

22. 

23. 

24. 

25. 

26. 

a= 

28. 

General. 

Exhaust Trail Areas. 

Engine Frontal Areas and Cooling Air Vents. 

Battery Areas and Vents. 

Lavatories, Galleys, and Cabin Floors. 

Wheel Wells and Landing Gears. 

Control Surface Recesses. 

Spot-Welded Skins. 

Hinges 

Lap Joints Between Aluminum Alloy Extruded Sections. 

Fluid Entrapment Areas. 

Electronic Package Compartments. 

Control Cables. 

Microbiological Fuel Contamination and Corrosion. 

1 

9 

9 

15 

15 

15 

15 

15 

16 

16 

16 

16 

16 

17 

17 

17 

18 
Page ii AC 20-64 CHG.1 

10/26/73 

Page No. 

CHAPTER 7. MAINTENANCE INFORMATION. 19 

29. L-188 Aircraft Maintenance Information. 19 

APPENDIX 1. STATION CHARTS. (1 page) 1 

Figure A-l. Basic Dimensions. 1 

APPENDIX 2. WING STATION CHARTS. (3 pages) 1 

Figure B-l. Wing Station Diagram. 1 

Figure B-2. Wing Skin Planks and Material Index. 2 

Figure B-3. Wing Access and Inspection Provision. 3 

APPENDIX 3. NACELLE STATION CHARTS. 

Figure C-l. Nacelle Station Diagram. 

(1 page) 1 

1 

APPENDIX 4. FUSELAGE STATION CHARTS. (4 pages) 1 

Figure D-l. Fuselage Stations Diagram (Serial Nos. 1001 

and Up). 1 

Figure D-2. Fuselage Stations Diagram (Serial Nos. 2001 

and Up). 2 

Figure D-3. Fuselage Contour Coordinates. 3 

Figure D-4. Fuselage Canted Section. 4 

APPENDIX 5. STABILIZER STATION CHARTS. (3 pages) 1 

Figure E-l. Stabilizers Stations Diagram. 1 

Figure E-2. Horizontal Stabilizer Stringer Identification. 2 

Figure E-3. Horizontal Stabilizer Stringer Identification. 3 

*APPENDIX 6. MAINTENANCE NOTES FOR WING STRUCTURAL AREAS. (57 pages) 1 

Figure F-l. Wing Section Upper Surface. 3 

Figure F-2. Wing Section Lower Surface. 5 

Figure F-3. Service Problem Areas. 7 

Figure F-4. Wing Upper Surface. 29 

Figure F-5. Wing Upper Surface. 30 

Figure F-6. Wing Lower Surface. 31 

Figure F-7. Wing Lower Surface. 32 

Figure F-8. Wing External Structure. 33 

Figure F-9. Wing Internal Structure. 34 

Figure F-10. Wing Lower Surface. 35 

Fiiure F-11. Wing Upper Surface. 36 

Figure F-12. Wing Upper Surface. 37 

Figure F-13. Wing Upper Surface. 38 

Figure F-14. Wing Upper Surface. 39 

Figure F-15. Wing Upper Surface. 40 

Figure F-16. Wing Upper Surface. 41 

Figure F-17. Wing Upper & Lower Surface. 42 * 
AC 20-64 CHG 1 

10/26/73 

* Figure F-18. 

Figure F-19. 

Figure F-20. 

Figure F-21. 

Figure F-22. 

Figure F-23. 

Figure F-24. 

Figure F-25. 

Figure F-26. 

Figure F-27. 

Figure F-28. 

Figure F-29. 

Figure F-30. 

Figure F-21. 

Figure F-32. 

Wing Upper and Lower Surface. 43 

Wing Lower Surface, 44 

Wing Lower Surface. 45 

Wing Internal Structure. 46 

Wing Lower Surface. 47 

Wing Lower Surface, 48 

Wing Internal Structure. 49 

Wing External Structure. 50 

Wing External Structure. 51 

Wing Internal Structure. 52 

Wing Upper Surface. 53 

Wing Lower Surface. 54 

Wing Lower Surface. 55 

Wing Upper Surface, 56 

Wing Upper 6 Lower Surface. 57 * 

Page iii 

Page No. 
AC 20-64 

8/l/69 

Page 1 

CHAPTER 1. MAINTEZMNCE INSPECTION NOTES 

1. INTRODUCTION. This advisory circular provides maintenance information 

which can be used by mechanics, repair agencies, owners, and operators 

in developing maintenance programs, making improvements in existing 

programs, and conducting inspections and repairs on certain structural 

parts of the Lockheed L-188 series of airplanes. The material is based, 

in part, upon information made available through discussions with personnel who have maintained these types of airplanes for thousands of 

hours of time in service. The intent of the circular is to impart some 

of this knowledge to other interested persons so that it is not lost. 

2. DESCRIPTION. The circular contains guidance material for performing 

inspection and maintenance on wing, fuselage, empennage, flight controls, 

and landing gear structures. The information has been derived from 

service experience. It does not comprise a full and complete maintenance 

program for the subject aircraft but should be considered as supplemental 

maintenance data. Included in the circular are diagrammatic sketches and 

station identifications of the wing, fuselage, and fligkrt controls. In 

addition, there is a listing of selected maintenance difficulties which 

have been reported during 1967 and 1968. 

3* BACKGROUND. 

a. Aircraft Use. The agency has realized that several different types 

of transport aircraft are being phased out of service by some airlines because of the availability of newer equipment. Such older 

aircraft are being purchased by other operators who may not be 

familiar with the scope of required maintenance and the means which 

have been used to keep the aircraft in a safe and airworthy condition. 

b. Maintenance "Know How." Since maintenance "know how" is not transferred with the aircraft, the new operator generally goes through a 

learning cycle before he is able to rapidly pinpoint the critical 

problem areas of the aircraft. In this respect, identification of 

known areas where structural problems have been experienced will 

help in the preparation of an initial maintenance program by a new 

operator. It can also serve as a guide to other operators who have 

not accumulated sufficient experience to have knowledge of all the 

problem areas of the aircraft. 

4. GENERAL INFORMATION. 

. a. Manufacturer's Bulletins. It must be emphasized that the manufacturer 

has published several service bulletins concerning the inspection, 

repair, and modification of Lockheed L-188 series aircraft. Service 

bulletins highlight the importance of maintaining structural integrity 

on aircraft with particular reference to areas known to have experienced crack and corrosion damage. Operators are urged to become conversant with the manufacturer's recommendations and make certain that 

responsible maintenance personnel are knowledgeable on this subject. 

Chap 1 Par 1 
Page 2 AC 20-64 

8/l/69 F 

b. Airworthiness Directive. It is emphasized that the material in this 

circular does not supersede any of the requirements of airworthiness 

directives issued under Part 39 of the Federal Aviation Regulations. 

5. TYPE OF CONSTRUCTION. The major structural components of the aircraft 

are tne wing group, tne fuselage group, and tail group. The primary 

structure, shown in detail in this manual, consists of the fuselage, 

nacelles and the box beam sections of the wing and the vertical and 

horizontal stabilizers. These components have been designed in accordance 

with the "fail safe' policy. This policy provides multiple load paths 

and reduced stress levels, such that a single failure of any structural 

element will not result in the loss of the complete structural component. 

a. The wing is an all-metal, full cantilever-type structure and consists 

of a center section, an outer section, flaps, fillets and ailerons. 

The primary structure of the wing incorporates two main beams, upper 

and lower extruded surface panels, and ribs to stabilize the structure 

and maintain surface contour. Wing flaps are actuated by ball-bearing 

screw jacks and travel on steel tracks. The internal structure and 

skins are fabricated of aluminum alloy. Ailerons and trim tabs are 

of conventional design and constructed of aluminum alloy. Leading 

edges are attached to the front beam by hinges and incorporate provisions for ice elimination. Trailing edges are fabricated by the 

use of the metal-bond process, an outside skin bonded to an inner 

beaded skin. A major portion of the lower trailing edge is sectioned 

into hinged doors for inspection and maintenance. 

b. The fuselage is of conventional semimonocoque construction, using 

skin, stringer, and circumferential-frame combinations. The skin 

panels, for-the most part, are made of 2024-T3 or -T4 material. 

Large doublers, made of the same materials and usually them-milled, 

are used around doors, windows, and, generally, around all cutouts in 

the skin. The frames from station 200 to 1110 are mainly 19 inches 

apart with reinforced structure in the propeller and door areas. 

Stringers are made, for the most part, of formed sheet-metal sections, 

except near openings where heavier extruded sections are used. The 

floor support structure consists mainly of extruded vertical and 

transverse members attached to the fuselage frames. In the center 

section (over the wings) and in the nose section, longitudinal beams 

support the floor. Floor panels are of plywood in the aisles and 

vestibules, and metal-honeycomb-sandwich elsewhere. The latter contains electric-heating elements in passenger seating areas. 

The entire fuselage is pressurized between the forward pressure bulkhead (forward of and below the flight station) and the rear pressure 

bulkhead (rear of the lounge or aft lavatory). The main manufacturing 

joints are at stations 200 and 1117. Along the main passenger compartment from station 219 to approximately 968, the fuselage is a 

constant section. 

Par 4 chap1 

‘7 

a-. 

i 

c 

. 

. 

3 
AC 20-64 

8/l/69 

page 3 

c. The stabilizers consist of the horizontal stabilizer and tips, 

. elevator and tabs, vertical stabilizer and tip, rudder and tab, ' 

fillets, and dorsal. Each member has an all-metal aluminum frame 

covered with aluminum skin, The horizontal stabilizer is attached 

to the fuselage tail section by four continuous beam caps and four 

continuous stringers. The vertical stabilizer is attached to the 

fuselage tail section by the extension of four beam caps and four 

, stringers, .The ~orsa1,j.s connected to the fuselage by means of an 

attaching .angle. , There $s a shear pin that connects the top of the 

dorsal to the vertical stabi&er at fuselage station 1117, 

. 

6. ,GENEWL VISUAL INSPECTION TIPS. The primary structure of the aircraft 

Is designed to provide resistance to variable forces imposed while in 

operation by dispensing the forces through a structural pattern of 

“force flow” to the primary structural members of the wing and fuselage. 

External indications of failure, such as distorted skin, tilted or 

sheared Sivets, and tom, dented, cracked, or corroded skin are usually 

obvious. Wrinkled skin, “oil cans, “’ and tilted rivets, adjacent to 

the obviously failed area often indicate secondary damage caused by 

transmission of stress from the failed area. Misalignment of doors and 

panels may indicate distortion of internal structure. Internal structural damage, although not always apparent, may be found by closely 

examining the exterior surface. For example: 

a. 

b. 

Buckled skin betheen rivets at the end of a stiffener or stringer 

could mean that the last attaching rivet has failed, or that the 

stiffener or stringer is buckled in the area of the skin buckle. 

When a detailed inspection of the failed area is to be performed, 

functional parts should be actuated to determine if the failure has 

caused binding. ' . 

Deep diagonal skin buckles, located Qver a frame, former, or rib, 

could mean the member is distorted. When doubt exists concerning 

internal condition, the area in question should be opened and 

carefully Inspected. 

7. NONDRSTRUCTNETESTING (DT). Simply stated, nondestructive testing is 

preventive maintenance. This includes utilization of such maintenance 

tools as X-ray, ultrasonic, magnetic particles; eddy current, dye 

penetrant,.and others. 

r 

a. Maintenance Inspection> NDT permits maintenance inspections without 

removing components from air&aft or tearing down complex assemblies. 

Defects in various aircraft systems which would escape detection 

through normal visual inspection can be identified by NET. 

. 

b. Training Required. Special NlYT training is,desireable to make sure 

that the operator is capable of operatifig the equipment and interpreting the results. Also, many states require that an X-ray operator 

Chap 1 Par 5 
Page 4 AC 20-64 

8/l/69 

have an approved certificate for use of X-ray in industrial applications. This is to minimize improper use with attendant health 

hazard of X-ray equipment. 

10. 

AIRCRAFT STATION DIAGRAMS. The wing, fuselage, and empennage station diagrams included in this document were developed for the L-188 aircraft and 

are used as a general reference only. Several models of these aircraft 

were manufactured and have different station locator numbers based on the 

particular configuration. Since the defective areas generally apply to 

all models of aircraft, the referenced area can be compared with a 

similar area and locator on the appropriate station diagram for the 

particular model of aircraft. (See Appendices 1 through 5.) 

DEFINITIONS. 

a. Fatigue. The progressive fracture of a metal by means of a fault 

which develops and spreads under repeated cycles of stress. 

b. Stress. The force per unit area of a body that tends to produce a 

deformation. 

c. Stress raiser. A scratch, groove, rivet hole, forging defect, or 

other structural discontinuity giving rise to a focal point for a 

local concentration of stress. 

d. Corrosion. Gradual destruction of a material by chemical action. 

Often evidenced by oxide buildup on the surface. 

ABBREVIATIONS USED IN THIS DOCUMENT. 

AD 

FBC 

FCD 

FS 

HSS 

UK! 

MEC 

NLG 

P/N 

SB 

SIL 

Tr 

TAT 

TSN 

TSO 

TST 

vss 

ws 

Airworthiness Directive 

Fixed base check 

Fleet campaign directive 

Fuselage station 

Horizontal stabilizer station 

Lockheed aircraft 

Main base check 

Main landing gear 

Nose landing gear 

Part number 

Service Bulletin 

Service Information Letter 

Total time 

Total aircraft time 

Time since new 

Time since overhaul 

Total ship time 

Vertical stabilizer station 

Wing station 

Par 7 Chap 1 
AC 20-64 

8/l/69 

Page 5 

cHApTER2. WING 

11. L-188 AIRCRAFT MAINT~CE INFORMATION. The following is a listing of 

significant maintenance difficulties that have been reported by air 

carriers. This information may be useful in identifying structural 

inspection areas. Except where noted, wing structural references apply 

, to both left and right wings. I' :. 

Lockheed Reference 

a. Lower Wing Skin Planks. For Details 

0) 

(2) 

(3) 

0 

(5) 

Lower wing skin plank damage was caused 

by integral engine start system compressor 

line rubbing in #2 and #3 nacelles. 

Cracks occurred in the lower #3 wing skin 

plank forward of the MIG fulcrum fitting. 

(Over gOC hoursTSN.) 

SB 587 alert wire was issued to inspect #& 

lower wing plank drain hole for cracks at 

station 159. 

SIL-61 

10/q/62 

SB 601 

6/2’+/63 

SB 587~ 

4/10/64 

Plus AD 

65-15-4 

Cracks have been found at the fastener holes SB 631 

around the fuel sight gage and fuel overflow g/6/6 

opening6 on the left- and right-hand lower 

wing planks. The crack6 occur at Wing 6tatiOn 

128.0 and in the wing reinforcing doubler at 

station 266.0. 

Cracks have been found in lower wing plank #l SB 653 

between WS 205 and WS 275. 713168 

b. Upper Wing Skin Planks. 

(1) Crack6 have been found which appear to be 

static fracture6 originating on the #l 

upper wing plank inner surface. 

SB 565 

4/27/62 

(2) Cracks have been found in the upper surface SB 6lgA 

in the area of the main landing gear rib 5121165 

forgings. These areas were previously rein- P1U6 m 

forced by doublers in accordance with SB 65 -g-4 

306 and 337 except aircraft, LAC! serial #1145 

thru 1148 and 20204022, which were delivered 

with internal reinforcements. 

Chap 2 Par 11 
Page 6 

(3) Cracks have been found at screw holes In the 

wing upper plank #2, at the plank #l and #2 

splice between WS 212.0 and 230.0. 

(4) Cracks have been found In the trailing edge of 

wing planks #6, #, and fi at wing statlor. 143 

LEFT and RIGRT upper surface. In two cases, 

the backup fitting, P/N 803900, for the flap 

track attachment was also cracked. 

(5) This reference applies to the Inspection of 

wing plank splices aft of the main landing 

gear fulcrum fitting and provides additional 

repair Instructions for the WS 209 area (see 

d(2) page 7). 

(6) This revlslon provides Instructions to reduce 

the possibility of cracks developing In the 

upper wing planks under the nacelle skate 

angles. The original bulletin pertained only 

to the inboard nacelle skate angles, but this 

revision supplies reinforcement for ALL 

nacelle skate angles. 

(7) A considerable number of cracks have been found 

in the #l upper wing plank at the nacelle 

fillet attachments. Cracks have been found at 

the inboard side of all four nacelles at the 

attachment of the nacelle fillet with the 

upper #l plank. 

(8) Cracks have been found in the #3 upper wing 

plank along the first row of fasteners 

adjacent to the skate angle of the outboard 

nacelle at WS 346.0. 

c. Outer Wing to Center Wing Attach Fittings. 

This SB revisionwas issued to identify 

requirements for the outer wing front cap fittings, 

P/N 807352 and P/N 807354; specifically, corrosion 

of fittings,attachment bolts, and boltholes. 

d. Wina - MLC Ribs. These service bulletins instruct 

Par 11 

operators as follows: 

(1) To inspect the MLC ribs in each wing for 

fatigue cracks in the web fillets at the 

junctures of the rib truss members with the 

rib upper chord member. Similar cracks 

AC 20-64 

8/l/69 

SB 632 

VW65 

SB 634~ 

W8/65 

SB 625~ 

5/16/66 

Plus AD 

66-11-2 

SB 6oOA 

2/21/60 

Plus AD 

64-u-3 

SB 649 

%%? 

Plus AD's 

68-11-2 

68-23-5 

SB 652 

4/30/68 

SB 633A/633B 

g/3/65 & 

g/24/65 

Plus AD 

66-5 -3 

SB 630 

7/a/65 

II . 

. 

ruy= 

chap 2 

. . . -.xqw.sq,---s- 
AC 20-64 

8/l/69 

Page 7 (and 8) 

have also been found in the web fillet 

between the forward truss member and the 

upper chord member beneath the #3 wing plank. 

(2) To inspect the vertical legs of the upper and SB 639 

lower caps of the wing ribs for cracks at 11/7/66 

wing stations 167 and 209. 

e. Wing-to-Nacelle Attachment Plate. Cracks have been SB 638 

found in the wings-to-nacelle attachment plate, 10/17/66 

P/N 810054-1, which is located inside the inboard 

nacelle on the lower front beam of the LEFT WS 209. 

(Propeller torque loads on the #2 nacelle augment 

the normal stresses on this plate.) 

f. Wing Rear Beam Clips. Cracks have been found in P/N SB 654 

805483-l (WS 179), and P/N 805491-l (WS 197) rib 418168 

attach clips location (dry bay area), at the rear 

beam forward face upper attachment. Cracks occur 

in the 0.16 radius of the flange relief cutout 

and extend toward the nearest fastener hole. 

t3* Wing Upper and Lower Access Door Lands. Corrosion SB 606 

found on the lower wing plank access door lands 11/18/63 

appears to be caused by condensation. (Door lands 

are the area surrounding the access opening in the 

wing plank.) 

Chap 2 

-c----.._rr_-_-l 

Par 11 
AC 20-64 

81 L/69 

Page 9 

CHAF’TER 3. FUSELAGE 

12. L-188 AIRCRAFT MAINTENANCE INFORMATION. The following is a listing of 

significant maintenance difficulties that have been reported by air 

carriers. This information may be useful in identifying structural 

inspection areas. Except where noted, fuselage structural references 

apply to both left and right sides. 

Lockheed Reference 

a. Fuselage Stringers Station #lll'j'. This For Details 

service bulletin provides for inspection SB 574 

of the underfloor stringers at the aft 

pressure bulkhead for cracks. The 

bulletin was later revised to cover all 

underfloor stringers, 1 thru 72. 

b. Flight Station Pressure Deck. Cracks have 

been found in the flight station pressure 

deck structure, butt line 40 right beam, 

lower beam cap flange. Cracks in this location could result in a loss of cabin pressure. 

Reported cracks have occurred on aircraft 

with over 13,000 total flight hours. 

lo/3162 

Revised 12/26/62 

SB 609A 

11/2/63 

Revised 3/30/65 

c. Forward and Aft Cargo Door Frame Corners. 

Cracks have been found in the lower forward 

and aft cargo door frames. 

d. Fuselage Main Frame Fittings. A considerable 

number of cracked main frame fittings have 

been found at FS 570 and FS 695 

e. Fuselage Bulkhead Ring Intersection with Center SB 646 

Wing. Cracks have been found at the intersection 4/12/68 

SB 608~ 

2/5/65 

Revised SB 608B 

2/18/65 

SB 644 

2/10/67 

Revised SB 64kA 

1215167 

Plus AD .I 

67-11-4 

between the wing center section lower surface ' ‘ 

and the fuselage rings at fuselage stations 571 

and 694. 

f. Cabin Window Support Structure. Cracks have SB 647 

been found in fuselage station 853.5, (cabin 5/6/68 

window support structure.) 

Chap 3 Par 12 
Page 10 AC 20-64 

8/l/69 

g. Canted Fuselage Frame Upper Web. Cracks have been SB 579 

found in the canted frame upper web, station 1167.7. 1&g/63 

(See figure D-4 in appendix 4, page 4,) Revised SB 579A 

61171643 

Plus AD 

63-17-3 

Par 12 Chap 3 

-...w
AC 20-64 

81 l/69 

Page 11 

CHAPTER 4. FLIGHT, CONTROLS 

13* L-188 AIRCRAFT MAIR'l?ENANC!E INFORMATION. The folltilng ie a lietlng of 

significant maintenancg difficultiee that have been reported by air 

carriers. This information may be useful In Identifying structural 

Inspection areas. Except where noted, flight control structural 

references apply to both left and right sides. 

Lockheed Reference 

For Details 

a. tipennage . 

(1) 

(2) 

(3) 

(4) 

(5) 

(6) 

Elevator Counterweight Inetallation. 

Exceselve cumulative free play hae been 

found In the joints of the elevator 

counterweight balance arm linkages. 

SB 45’7 

7/15/a 

Empennage Drain Hole, This service bulletin SB 573 

was Issued to prevent moisture accumulation g/26/62 

in the empennage by providing improved 

drainage. 

Canted Fuselage Station 1167.7 Frame Upper 

Web. Cracks have been found on both sides 

ofhorizontal stabilizer station 29 at the 

lower cap in the 0.62-inch radius. 

SIL-62 

11/q/62 

Rudder Trailing Edge. Cracks have been found SB 602 

in the outer skin and beaded inner skin of the 7/3/63 

rudder trailing edge. Cracks starting from 

holes at the aft end of the beads weaken the 

structure and cause additional cracks to 

develop in the outer skin at the spotwelds. 

Spotwelds that may crack are located l-$ to 2 

inches forward of the rudder trailing edge. 

Vertical Stabilizer to Fuselage Attach Channel. SB 616 

Cracks have been found in the vertical 

stabilizer to fuselage attach channel, P/N 

7/24/a 

Revised SB 61th 

803179-5, located at fuselage station 1117.6. 4/5/65 

Plus AD 

65-21-5 

Elevator Balance Weight Arms and Ribs. This SB 567 

modification will eliminate repeated inspec- Revised 5/y/62 

tion of the elevator balance weight arms SB 567~ 

(for cracks), required by the original SB 

567, revision 1, dated 12/3/62. 

7/30/65 

chap 4 Par 13 
Page 12 AC 20-64 

8/l/69 

b. Ailerons. 

0) 

(2) 

(3) 

Aileron Skin Doublers. Cracks have been SB 444 

found in the lower aileron skin between 5/27/a 

the trim tab actuating rod access door and 

the rear beam, notably in the area where the 

forward and aft flanges of the internal 

beaded doublers mate with the skin. 

Aileron Counterbalance Attaching Angles, 

Cracks have been found in the aileron 

counterweight attaching angles. 

SB 451 

5/10/@ 

Revised T/25/60 

Plus AD 

60-25-2 

Aileron Push-Pull Tubes. Cracks have been SB 607 

found in the aileron push-pull tubes, also 10/17/63 

wear, and misalignment of the support Plus AD 

assemblies and rollers. 64-16-4 

C. Flaps. 

(1) Wing Flap Torque Tubes. Operators have SB 570 

reported flap torque tube support bearings 

binding and/or rubber sleeves deteriorated 

6/x)/62 

or missing. This results in torque tube 

wear caused by this tube turning in the 

inner race of the P/N KP16BS bearing. 

(2) Wing Flap Track Attaching Bolts. Operators %&$ 

have reported extensive damage to a flap 

due to the failure of the outboard lower Revised SB 59lA 

flap track attach bolts. l/7/64 

Par 13 chap 4 

" ."e.m
AC 20-64 

8/l/69 

Page 13 (and 14) 

CHAPTER 5. LANDING GEAR 

14. L-188 AIRCRAFT MAINTENANCE INFORMATION. The following is a listing of 

significant maintenance difficulties that have been reported by air 

carriers. This information may be useful in identifying structural inspection areas. Except where noted, structural references on the main 

landing gear (ML@ refer to both left and right gears. 

a. 

b. 

C. 

d. 

e. 

f. 

Main Landing Gear Actuator Support Fittings. 

Cracks have been found in the MU3 actuator 

support fittings, P/N 800618. 

Main Landing Gear Actuating Cylinder Attach 

Fitting Intercostal. During accomplishment of 

SB 538, a crack was found in the wing plank 

surface of one aircraft and a crack in the wing 

plank riser of another aircraft. Both cracks 

were located under the MW actuator cylinder 

attach fitting. 

Nose Landing Gear Steering Housing. Cracks have 

been found in the nose landing gear steering 

housing. These housing cracks originate at the 

Lockheed Reference 

For Details 

SB 599A 

10/22/63 

SB 593 

7112163 

SB 593B 

l/24/64 

Plus AD 

64-14-5 

SB 576 

10/29/62 

Revised 418163 

inboard end of the 4-l/8" - 12 UNS-3A screw thread SB 576B 

that receives the retaining nut of the steering 3117164 

cylinder. The cause is attributed to fatigue Plus AD 

failure of the thread root. 66-28-4 

Nose Landing Gear Assembly Trunnion Locking 

Slots. Cracks have been found in the fulcrum 

bearing spacer locking slots in the NU LEFT 

trunnion arm. 

MlG High Heat Treat Steel Plating and Stripping 

Practices. Landing gear shock strut components 

have failed in service after passing through major 

overhaul and replating procedures. 

Main Landing Gear Lubrication. This SIL outlines 

revised maintenance procedures and improved 

lubricants for landing gear static and dynamic 

joint corrosion protection. 

SB 604 

10/18/63 

Revised SB 604B 

6/29/65 

SIL-88 

7125166 

sn-32 

5/23/62 

Chap 5 Par 14 
AC 20-64 

8/l/69 Page 15 

CHAPTER 6. CORROSION PRONE AREAS 

15d 

16. 

17. 

18. 

1.9. 

GENERAL. Corrosion is most likely to strike at the joints or attachment 

points in metallic structure because they provide entrapment areas for 

corrosive agents and moisture to accumulate. However, the problem can 

be compounded if metallic surfaces are exposed to an extremely corrosive 

environment, or if the surfaces are difficult to inspect and clean. The 

most important corrosion preventive measure is to keep them clean and 

dry. 

EXHAUST TRAIL AREAS. Both jet and reciprocating engine exhaust deposits 

contain compounds that are very corrosive, and the structure in the path 

of exhaust gas is more likely to suffer from corrosion than is any other 

structure. It is customary to coat structure exposed to exhaust gases 

with protective finishes to prevent these gases from coming in direct 

contact with the metal. However, the deposits which collect on top of 

the protective finishes must be removed before they permeate the film 

and attack the metal. Most troublesome are those areas where exhaust 

gas deposits may become entrapped and cannot be reached by normal 

cleaning methods. Typical of these areas are seams, gaps, hinges, or 

fairings located in the exhaust gas path. 

ENGINEFRONTAL AREAS AND COOLING AIR VENTS. These areas are subject to 

erosion by airborne contaminants, rain, and from foreign objects on the 

runways. Erosion will remove the protective finishes or oxide film 

from the metal surfaces, leaving them vulnerable to corrosive attack. 

In addition, much of the equipment installed within these recesses is 

also vulnerable to corrosion. When an aircraft is operated in a marine 

environment, salt deposits may accumulate in these areas and the ensuing 

corrosive attack can be rapid and destructive. It is imperative that 

these areas be frequently inspected and cleaned, and protective finishes 

be maintained. 

RATTERYAREASANDVENTS. Due to the'highly corrosive nature of battery 

acid (sulfuric acid) and its fumes, battery areas and their vents are 

protected by special acid-resistant paints. Generally this is enough to 

stem the tide of corrosion if scrupulous attention is devoted to keeping 

these areas clean. 

LAVATORIES, GALLEYS, AND CABIN FLOORS. The usual spillage, condensation, 

and other contamination of these areas are extremely corrosive to aircraft 

metals. The most common corrosive agents are acidic foods and beverages, 

and human excreta. Also, most chlorinated disinfectants are acidic and 

corrosive, and cannot be recommended for use in aircraft. It is impractical to assume that these areas can be kept clean and dry at all times, but 

it is important to inspect the structure carefully at suitable intervals, 

cleaning and renewing the finish as necessary. Areas behind lavatories, 

sinks, or ranges where waste may collect are potential trouble spots, as 

are personnel relief and waste disposal vents or openings on the exterior 

of the aircraft. 

chap 6 Par 15 
w. 

21. 

22. 

23* 

e4. 

16 AC 20-64 

8/l/69 

WHEEL WELLS AND LANDING GEARS. Equipment installations in the wheel well 

areas probably absorb more punishment than any other portion of an aircraft because they are exposed to moisture of flying debris during takeoffs and landings, and when the aircraft is parked they are exposed to 

atmospheric moisture. After an airplane has entered service, it is 

difficult to maintain protective paint film on landing gears, equipment 

installations, and wheel well surfaces because the many complicated 

shapes, assemblies, and fittings in these areas obscure other surfaces. 

Items that should receive special attention during wheel well inspections 

are: 

a. Magnesium wheels (especially the areas around the bolt heads, lugs, 

and wheel webs). 

b. Portions or rigid tubing obscured by clamps and identification tapes, 

c. Exposed electrical equipment. 

d. Crevices between ribs, stiffeners, and lower skin surfaces which can 

serve as water or debris entrapment areas. 

Corrosion control in wheel well areas may best be attained by frequent 

cleaning, lubrication, paint touch-up and judicious use of wheel covers, 

CONTROL SURFACE RECESSES. Control surface recesses are potential 

problem areas because normally they are difficult to inspect. If 

corrosive agents gain entry and accumulate in these areas, they may go 

unnoticed for some time. Frequent inspection and cleaning of the 

surfaces and installations located in these recesses will prevent 

corrosion from gaining a foothold. ' 

SPOT-WELDED SKINS. L'orrosive agents may become entrapped between the 

layers of metal adjacent to the spot-weld beads. If moisture enters the 

area, an electrolytic cell can be set up between the dissimilar metal 

phases in the spot-weld area, and one or more of these phases will be 

subject to preferential corrosive attack. Whenever practical, 

structural areas with spot-welded assemblies should be sealed to prevent 

the ingress of contaminants and moisture. 

HINGES. Hinges are natural traps for corrosive agents. Often they are 

susceptible to galvanic corrosion when the hinges and pins are made of 

dissimilar metals. The most practical means of corrosion control is to 

inspect and lubricate hinges frequently. After lubrication, actuation 

of the door through several cycles is necessary to ensure complete 

penetration of the lubricant. 

LAP JOINTS BETWEEN ALUMINUM ALLOY EXTRUDED SECTIONS. Extruded sections 

of high-strength materials such as 7075 or 7178 aluminum alloys are more 

susceptible to intergranular corrosion than are other aluminum alloys. 

Application and maintenance of chemical processes, sealants, paints, or 

Par 20 

._--__ I- - 

chap 6 

. ~ .-sln
AC 20-64 

8/l/69 

Page 17 

combinations of these protective measures have proven 

controlling corrosive attack on these materials. 

most effective in 

If intergranular corrosion occurs, it is usually found around fasteners 

or in lap joints. It is evidenced by raised areas or lumps under the 

paint film, and there have been instances where the attack has progressed to such an extent that there were actually bulges in the faying 

surfaces. These raised areas, lumps, and bulges are due to the 

accumulation of corrosion products,which take up more volume than did 

the affected material before it corroded. 

25. FLUID ENTRAPMENT AREAS. Design specifications require that aircraft 

have drains installed in areas where water may collect. However, if 

drains are rendered ineffective because they are clogged by debris, 

sealant, etc., or because the level of the aircraft is changed from 

that of a normal ground attitude, corrosive agents can collect in a 

localized area. Low-point areas and drains should be inspected 

frequently to prevent the inception of corrosive attack. 

Low points of integral fuel tanks are areas where water condensate can 

collect. This water and condensate is of doubtful purity, and if 

permitted to stand it can permeate the protective coating of the tank 

and bring many corrosive agents held in suspension in contact with the 

vulnerable metallic surfaces. Water condensate should be drained 

regularly from fuel tanks and the integrity of the tank sealant 

maintained to prevent corrosion of integral tank surfaces. 

When considering fluid entrapment areas, one inevitably thinks of 

aircraft drinking water and wash water systems. Corrosion in these 

systems is rare because they are fabricated from nonmetallic 

materials and/or stainless steel. Water stagnation should pose no 

problems so long as sanitation regulations are heeded. 

26. ELECTRONIC PACKAGE COMPARTMENTS. Often the safety of those on board 

an aircraft rests on the proper function of a little black 2,13x. The 

environment of electronic package compartments is carefully controlled 

to provide the most ideal conditions that can be achieved. The degree 

to which such sensitive equipment is exposed to corrosive agents is 

very small, but even small quantities of moisture and contaminants 

can adversely affect equipment reliability. Components in these a?- as 

should be inspected for corrosive attack as thoroughly as poss?bduring routine checks, and advantage should also be taken of IUFscheduled component removals for further inspection. 

2% CONTROL CABLES. Control cables have preservative coatings which, 

when intact, prevent corrosive attack. Due to their vi+ f-c;:-ction 

it is necessary to inspect these cables frequently to endtire that 

they are adequately protected. During these inspections incipient 

failures due to other causes also ma: be detect:?d. It is recommended 

that control cables be inspected periodically, then cleaned and 

treated as necessary before reapplication of the preservatives. 

Chap 6 Par 24 
Page 18 AC 20-64 

8/l/69 

28. MICROBIOLOGICAL FUEL CONTAMINATIz>N AND CORROSION. Microbiological 

contamination in turbine fuel is caused by bacteria and fungi which 

feed on the constituents of the turbine fuel. The result is a sludge, 

or mat deposit, which ha&been found in some aircraft fuel tanks and 

is often loosely referred to as green slime. However, some deposits 

have been found in various shades of grey, brown, red, and white. If 

allowed to develop and grow in the aircraft fuel tanks, microbiological 

contamination can cause a myriad of problems not the least of which is 

severe aluminum alloy corrosion in the aircraft integral fuel tanks. 

Since the subject is large and complex, we recommend Lockheed's "Field 

Service Digest" issue of March-April 1961, Volume 7, Nwnber 5, which 

is devoted to a full explanation of microbiological contamination, 

corrosion, treatment and prevention. Likewise, we recommend Lockheed's 

"Field Service Digest" issue Number 49, dated December 1965, which is 

devoted to general corrosion detection, removal, and control. 

Par 28 

--- . . - . . . . , I . . 
AC 20-64 

8/l/69 

cHAPTm7. MAINTEXKNCE INPORMATION 

Page 19 

29, ’ L-188 AIRCRAFT MAINTENANCE INFORMATION, The following is a listing of 

significant maintenance difficulties that have been reported by air 

carriers as mechanical reliability reports from 1967 and 1968 ADP 

records, Thi6 information may be useful in Identifying additional 

structural inspection problem areas, In all cases, check the correepolilding trouble area, left right, top bottom, forward aft, etc. /- . 

a. Wing. 

:. (1) 

(2) 

(3) 

(4) 

(5) 

(6) 

(7) 

(8) 

During a routine visual inspection, two cracks were found in 

the lower right forward front beam cap wing stub fitting, P/N 

819229. Each crack was 1 inch long at butt line 65, Another 

crack 1 inch long was found at the top vertical support Tangle at station 49 below No. 6 wing plank. The aircraft 

total time was 19,451 flight hours. 

During a visual inspection, the lower left inboard forward 

wing-to-box-beam fitting, P/N 81922gd, was found cracked, 

An 18-inch spanwise crack progressing outboard from WS 155 at 

the splice between #3 and #& upper right wing planks was 

found during a visual inspection. 

During a fleet campaign using visual, magnifying glass, dye 

penetrant, and horoscope inspection methods, the forward top 

beam cap inboard of No. 2 nacelle at station 165 was found 

cracked. The cracks were one-eighth inch long and emanated 

from a screw hole towards the aft end of the beam cap. The 

aircraft total time was 21,953 flight hours. 

During maintenance, the left wing truss rib was found cracked 

at station 167. The total airframe time was 20,378 flight 

hours. 

During a visual inspection a b-inch crack was found in the 

left rear beam wing stiffener at station 204.7. The aircraft 

total time was 20,254 flight hours. 

A routine maintenance inspection revealed a j/h-inch crack in 

the left wing forward lower spar cap tang at station 331. 

The airframe total time was 22,311 flight hours. 

During a scheduled ultrasonic inspection, the following 

cracks were found: 

Chap 7 Par 29 
Page 2b AC 20-64 

8/l/69 

(a) A 36.inch crack was detected at the forward end of No. 2 

fuel tank access plate at the forward end of No. 4 wing 

plank. The crack extended from a point midway in the 

access plate to a point 36 inches inboard of the access 

plate. The crack depth varied from six thousandths of an 

inch to complete fracture over a 2-inch span. 

(b) The same type crack (as (a) above) was found at No. 3 

,fuel tank access plate. The crack extended from a point 

midway in the access plate to a point outboard of the 

access plate. 

(c) During a fleet campaign inspection, l/b-inch cracks were 

found emanating from the inboard No. 3 nacelle fillet 

fairing first and third.attaching screw holes in No. 1 

wing plank. The aircraft total time was 21,563 flight 

hours. 

(9) On a routine inspection, the No. 4 sight gage aft mounting 

screw hole was found with a l-inch crack in the leap doubler. 

The airframe total time was ~1,708 flight hours. 

(10) During inspection wing skin cracks were found at two screw 

,holes around fuel gages between No. 3 and No. 4 nacelles. The 

aircraft total time was 22,287 flight hours. 

(11) Inspection disclosed a 3-inch crack in the inboard side of the 

No. 4 fuel tank surge box. The total airframe time was 

21,528 flight hours. 

(12) Maintenance inspection revealed a crack 5 inches aft of the 

hinge on the access panel at the trailing edge of the wing, 

5 feet outboard of No. 4 engine. The aircraft total time was 

24,074 flight hours. 

(13) A l/2-inch crack was found in the left wing tip upper aft 

former. Total airframe time was 21,520 flight hours. 

(14) During a scheduled inspection a 3 l/2-inch crack was found in 

the left outboard wing-to-nacelle attach plate, P/N 818854-l. 

The crack occurred 1 5/8 inches from the bottom edge of the 

plate. Total aircraft time was 21,686 flight hours. 

(15) Overhaul inspection revealed random cracking of the wing and 

nacelle skin former webs and stiffeners at the following 

locations: 

(a) No. 1 nacelle former flange outboard side station O,OPar 29 Chap 7 
AC 20-64 

a/ 1169 

04 

( C ) 

b. Fuselage. 

0) 

(2) 

(3) 

I 

(4) 

(5) 

(6) 

(7) 

(8) 

Page 21 

No. 2 nacelle former attach angle at lower outboard 

longeron at aft hinge for Nb. 1 main landing gear door. 

No. 3 nacelle attach angle at lower aft edge of 

forward main landing gear door. Total airframe 

was 17,700 flight hours. 

No. 3 

time 

Inspection revealed fuselage skin crack on the left side above 

the aft power receptacle. The airframe total time was 22,603 

flight hours. 

During a fleet campaign, three 1/2=inch skin cracks were found 

at the lower aft baggage door frame. Cracks occurred at the 

lower forward frame radius. Total aircraft time was 18,752 

flight hours. 

Inspection disclosed cracked corners above and .below the No. 9 

left and right emergency exit windows. Crack lengths were 

l/8 to 1 l/4 inches. The total airframe time was 17,797 

flight hours. 

During a routine visual inspection, a 2-inch crack was 

detected in the lower rear corner of the passenger door frame. 

Total time on the aircraft was 19,733 flight hours. 

During a visual inspection, a complete fracture of a fuselage 

web former was found at fuselage station 107.4. The crack was 

on the right side below the rudder pedals. Total time on the 

aircraft was 20,045 flight hours. 

During a walkaround visual inspection, confirmed by dye 

penetrant inspection, a 2-inch crack was found in a fuselage 

cap strip at station 118.8. The affected cap strip is on the 

right side of the nose gear wheel well, below the cockpit 

flooring. Total time on the aircraft was 22,547 flight hours. 

An overhaul inspection revealed two fuselage skin cracks, One 

was found on the left side of the fuselage at the nose wheel well 

cutout at' fuselage station 186. The other crack was found below 

and to the right of the No. 2 hydraulic pump, between 

stringers 28 and 29 at fuselage station 738. Time on the aircraft was 17,700 flight hours. 

During a dye penetrant inspection, a 3/8-inch crack was found 

in the right rear fuselage-to-wing attaching ring, P/N 

801031-102, located just above the floor line. Total time on 

the aircraft was 20,310 flight hours. 

Par 29 
Page 22 

(9) 

(12) 

(13) 

(14) 

(15) 

AC 20-64 

8/l/69 : 

A crack was found in a pressure web at butt line 40, fuselage 

station 195, The pressure web affected is located on the right 

side, Total time on the aircraft was 22,781 flight hours. 

A 1 l/e-inch crack was found in a former rib on the right side 

at station 550. The crack was located 6 inches below the floor 

level. Total time on the aircraft was 20,568 flight hours, 

During overhaul inspection, several fuselage structure cracks 

were detected as follows: 

(a) Former flange cracked on left and right sides of fuselage 

at stringers 30 and 31, station 570.97. 

(b) Former flange cracked at fuselage station 1150 at stringers 

7, 10, and 12 in the tail compartment. 

(c) Former flange cracked at station 1133, at stringers 70 and 

71 in the tail compartment, 

(d) Former flange cracked at station 768 at stringer 23 located 

above floor level in the hydraulic compartment. 

(e) Former flange cracked at upper aft end of forward cargo 

pit door. 

(f) Right side cabin floor beam flange cracked at station 652. 

(g) Right and left side cabin floor beam flange cracked at 

fuselage station 580 above the forward spar. 

During structural modification to a cargo configuration, the 

contractor found the left aft main fuselage frame fitting 

cracked at station 695. Total time on the aircraft was 19,276 

flight hours. 

During routine visual inspection, a 3-inch crack was detected 

across the belt frame at fuselage station 715.50. The crack 

was on the left side at the floor line. Total time on aircraft 

was 14,945 flight hours. 

During inspection, the belt frame on the right side of the 

fuselage at stringer 19, station 730, was found cracked 

through. 

During a scheduled inspection, stringer No. 37 was found 

cracked at fuselage station 1113. The crack occurred at the 

forward clip fastener hole. Total time on aircraft was 

19,778 flight hours. 

Chap 7 
AC 20-64 

8/I/69 

Page 23 

(16) Fuselage stringer No. 49 was found cracked at fuselage station 

1117. The crack occurred at the No. 5 fastener on the forward 

side at the rear pressure bulkhead. Total time on the aircraft 

was 20,842 flight hours. 

(17) Fuselage formers were found cracked at the 12 o'clock position 

at fuselage station 1133, and at the 9 and 2 o'clock positions 

at fuselage station 1158. Total time on the aircraft was 

21,898 flight hours. 

(18) Fuselage formers were found cracked at 9, 10, 11, 11:30 and 

2 o'clock positions at fuselage station 1150, and at the 9 

o'clock position at fuselage station 1167. Total time on the 

aircraft was 21,932 flight hours. 

(19) Right and left reinforcing angles, P/N 803185-47 and -48, 

were found cracked at station 1185. One crack was found in 

the former-to-skin attachment at fuselage station 1167, and 

another crack was found'at station 1133. Total time on the 

aircraft was 21,151 flight hours. 

(20) Fuselage former attach tab was found cracked at the 10 o'clock 

position at fuselage station 1193. Total time on the aircraft 

WM 22,207 flight hours. 

c. Flight Controls. 

. I 

0) Al l/2-foot fatigue.crack was found at the trailing edge of 

the wing flap. The crack was located aft of the JQlar strip at 

the rear of the No. 2 engine. 

(2) 

(3) 

(4) 

A9 1/2=inch crack was found on the right horizontal stabilizer 

front beam web near stabilizer station 29. Total time on the 

aircraft was 19,853 flight hours. 

During inspection, the No. 8 balance weight open type arm, P/N 

816g00-4, on the left elevator was found cracked. Total time 

on the aircraft was 19,452 flight hours. 

During main base check, a 1 1/2+nch crack was found in the 

vertical stabilizer right attach angle at station 1117, The 

crack had progressed three-fourths inch forward and aft 

through the Hi-Lok fastener hole. Total time on the aircraft 

was 19,437 flight hours. 

cwp 7 Par 29 
Page 24 AC 20-64 

8/l/69 

(5) Pilot reported No. 3 engine vibration indication at and above 

220 knots. The vibration was also noticeable by slight 

buzzing of the p?er lever on the ground. During cruise, a 

definite vibration was experienced in the ailerons, elevators, 

and rudder. The engine vibration was pronounced above 800 

degrees engine tailpipe temperature. Inspection of the control 

surfaces revealed rudder rib damage requiring reinforcement. 

The rudder was replaced. Total time on the airframe was 15,949 

flight hours. 

d. Main Landing Gears. 

(1) During overhaul inspection two j/&-inch cracks were found at 

the top of the left main landing gear inboard truss rib tabs 

at wing station 167. The cracks originated from the tab 

cutouts extending downward and aft toward the 

between risers Nos. 16, 17, 18, and 19 of the 

plank. Total time on the aircraft was 21,734 

(2) During inspection, the left main landing gear 

fitting, P/N 802058-1, was found broken. The 

holding the fitting in place. There were 857 

the last removal of the door actuator; Total 

aircraft was 20,268 flight hours. 

truss cap 

No. 3 upper wing 

flight hours. 

door actuator 

mounting bolt was 

landings since 

time on the 

(3) During a dye penetrant inspection, a 1/2=inch crack was detected 

on the left main landing gear actuator support fitting, P/N 

841275-101. The crack was located aft of the outboard hole. 

Total time on the aircraft was 14,356 flight hours. 

e. Corrosion. 

(1) 

(2) 

(3) 

During inspection, exfoliation corrosion was found on the left 

fuselage longeron, P/N 897596-1, between fuselage stations 

474.5 and 484.5. Total time on the aircraft was 20,740 flight 

hours. 

During a main base check inspection, corrosion was found in 

several spots on the aft cargo door fuselage doubler. The 

bottom edge of the aft cargo door sill is covered by a stainless 

steel striker plate. Total time on the aircraft was 17,721 

flight hours. 

Heavy corrosion was found on the floor beams at fuselage 

stations 333 and 371. Total time on the aircraft was 21,520 

flight hours. 

Par 29 Chap 7 

_--.-~ _ -. -. -- 
AC 20-64 

8/l/69 

Page 25 (and 26) 

(4) Three separately corroded areas were found on the left upper 

wing at station 65. The corroded areas were .030 inch deep 

and l/2 inch in diameter around the fuselage-fillet-to-wing 

attach fasteners at wing planks Nos.1, 6, and 7. Total time 

on the aircraft was 23,315 flight hours. 

(5) During scheduled inspection, corrosion was found on the lower 

wing surface. The corrosion occurred under the fuselage-towing fillet chafe strip at numbers 4, 5, and 6 wing planks. 

Four spots of corrosion were found measuring .Oll inch, .024 . 

inch, ,024 inch, and .013 inch. The areas were treated and 

and filled with epoxy filler before installing repaired 

doublers. Total time on the aircraft was 21,715 flight hours. 

(6) Corrosion was found on the lower section of the captain's 

sliding window frame. Total time on the aircraft was 21,620 

flight hours. 

(7) During inspection, an area of approximately 12 inches by 6 

inches on the outside skin at stringer No. 30 and fuselage 

stations 500 to 549 was found to be corroded beyond limits. 

Also, two small areas approximately 1 inch square were found 

corroded at stringer 22, fuselage stations 685 and 690. To-tab 

time on the aircraft was 24,649 flight hours. 

f. Miscellaneous. 

(1) 

(2) 

(3) 

An unscheduled landing was made as a precautionary measure due 

to in-flight cracking of the first officer's windshield. The 

windshield heat was in the low position. The aircraft was 

ferried to Buffalo, where the windshield was replaced. Flight 

time since the last inspection was 17 hours. Total time on the 

aircraft was 19,644 flight hours. 

The No. 4 oil cooler flap door was found cracked at the door 

actuator attach bracket. The crack was approximately one-half 

inch in length and progressed out of a screw hole toward the 

door hinge. The oil cooler flap door, P/N 836505-9, was 

replaced. Total time on the aircraft was 14,286 flight hours. 

During ground inspection, the No. 4 propeller oil access door, 

P/N 811567-11, was found excessively worn. The wear allowed the 

upper hinge end of the door to protrude sufficiently to be 

caught by the propeller blade cuff and be torn free. The 

aircraft was ferried to its main base,where the propeller cowl 

panel, P/N 813395027, was replaced and the propeller cuff 

repaired. 

chap 7 Par 29 
AC 20-64 

8/l/69 

Appendix 1 

Page 1 

FIGURE A-l. BASIC DIMENSIONS 

FWDFACEFRONT 

BEAMI 19.11% WORD 

F LWATORHINGE; 

OICHORD 

T 

42 FT 10 IN. 

AR FACE FRONT BfAM:15% CHORD4 FT7 5 IN 

FWD FACE REAR BEAM; 5056% CHORD- 

?A&? FT7 IN' C RUDDER HINGE, 6 AILERON HINGE: 72.5% CHORD- 1 -' - --- 

FUS 

STA 

571.19 

STATIC GROUND 

STA STA (95,OWLBS WITH 

42.00 171.oD C.G. B 2S%M.A.C.l 

-- - - .-. l1 * 4 'N*MAX "*--- +--3 FT3.7 IN. CLEARANCE 

WING REFERENCE PLANE 
l 

AC 20-64 

8/l/69 

FIGURE B-l. WING STATION DIAGRAM ' 

ACTUATOR TR$C; 

66.1 . 

t 

TRACK 

174.2. 

TRACK ACTUATOR 

241.5 242.3 

e 

TRACK 

313.8 

I 

FLAP STATIONS 

SEE NOTE A 

-I 

Id,, s 

FLAP STATIONS 

27.8 ~4wJ DRIVE (TRAILING EDGE STRUCTURE) 1 34.61 

1 I 1 

SCREW *4 ' ' e SEENOTEA 

125.3 

82.1/ lRfCK / 143.6 

5 

/I ’ TRACK All FPfBN FfAtl~NC 

FUS VA-, _ 

694.9 

I I I 

I ” 

72 101 143 167 197 221 257 293 

_. 

329 363 

t= WING STATIONS 4 I 

W.5 22. 

398 \ 

WS. W.S. I WING REFERENCE PLANE .- i 146.5 188 

I I i 

i &dM----=3- 

I -Tii! 11 ] 4 5% 

0.0 14 31 48 65 79 NACELLE 

I ! 

Q 

NACE LlE 

OUTER SECTION AND TIP 3 

NOTE 

A. FLAP STATION AND TRAILING EDGE STATION PLANES 

ARE PERPENDICULAR TO THE WING REAR BEAM. 

B. AILERON STATION PLANES ARE PERPENDICULAR 

TO HINGE CENTERLINE AND WING REFERENCE PLANE. 
Appendix 2 

Page 2 

AC 20-64 

8/l/69 

FIGURE B-2. WING SKIN PLMXSANDMATERIALINDEX 

FUS 

P sa, 

6949 .\ 

UPPER SURFACE 

STIFF. NO. 1 

NO. 61 

57 

NOTE 

SYMMETRICAL ABOUT B.LO.0. 

/ / LOWER SURFACE 

(ROTATEOlaf', 

TEE - LS4113 ITYP 2 PLACES), SEE 

51-3-6, FIGURE 1 (SHEET 21 

ATTACH ANGLE - LS66B1, SEE 51-3-6, 

FIGURE 1 (SHEET 21 

STIFF. NO. 1 7 INTERCOSTAL ASSEMBLY: 

INTERCOSTAL - 156258. SEE 51-3-6. 

61 

PANEL ITYPI - LS7255, SEE 57-2-1. FIGURE 3 

PANEL (TYPI - LS7256, SEE 57-2-1. FIGURE 3 

TUBE - 2024-T3 AL ALLOY 

TEE - LS4929 (TYP 4 PLACES), SEE 

51-3-6, FIGURE 1 t SHEET 21 

FlCURi I (SHEET 2') 

FITTING - LS63W2+6-557 

8 SPLICE PLATES - ml50 7075-T6 AL ALLOY 

9 SPLICE PLATE - .l!Xl 7075-T6 CLAD 
AC 20-64 

8/l/69 

Appendix 2 

page 3 

8 

FIGURE B-3. WING ACCESS AND INSPECTION PRCVISION 8 

LOWER TRAILING EDGE 

AILERON TRAILING EDGE 

* INDICATES A HINGED ACCESS DOOR. ALL OTHERS ARE REMOVABLE. 

A. 

B. 

C. 

4 

BOTTOM VIEW 

8 

q u TOP VtEW 

1 4” wtw B 22 

NOTE (ROTATED FOR CLARITY) 

LEFT SIDE SHOWN. ALL ACCESS OPENINGS 

ARE FOR RIGHT AND LEFT SIDES EXCEPT 

WHERE NOTED. 

REFER TO 54-0, FIGURE 3 FOR ACCESS TO 

WING IN VICINITY OF NACELLES. 

REFER TO 53-0, FIGURES 3 AND 4 FOR 

ACCESS TO WING IN THE CENTER SECTION. 

---m-m--- I n. . 

- - .-, ‘-2. 
‘.‘ . - -a.-..-_ ---_- _- - 

AC 20-64 Appendix 3 

8/l/69 Page 1 

FIGURE C-l. NACELLE STATION DIAGRAM NACELli STATIONS 

33.6 y.4 90;6 

L NAC 

W.L. 

-8.6 NiC 

STA INBOARD NACELLE 

-76.1 

NACELLE STATIONS 

-y2 18.0 

- n THRUST +. c I 

43i96 81,.5 

1119.n 

NAC 

W.L 

0.0 

hAC ; 

W.L NAc OUTBOARD NACELLE 

-84 STA 

- 67.2 

A. POWERPLANf STATIONING IS SAME 

FORlNBOAROANOOUTBOARONACELLES. 

POWERPLANTSTATIONS AREPERPENOICULAR 

L' TOTHRUSTCENTERLINE. 

. NACELLE STATIONSAREPERPENOICULAR 

TO NACELLE WATER LINE. 

Fi? P.P. 

STA STA 

120.6 95 

l?P. P.P. 

STA STA SE 

52.0 21.2 CL0 
758 

765. 

853.5 

872.5 

907. a 

c 

am a 

;e5e--?-----------J-j 371 352 6 

I 

397.5- 4044- -5 

41& 5- ’ 407 

:; 

z 

439.7- I ------426 !?I 

4% 5- ----- 445 

473.5-L 

!2 -447.3 F 

48&9-: 0 

464 

0 ,-483 

I 

511.5-L 1 I 

1 502 l 

U 530.5~) - -521 

549.5 

7”’ 578 

d-597 

625.5- 613.7 

-633*9637.4 
Appendix 4 AC 20-64 

Page 2 8/l/69 

FIGURE D-2. FUSELAGE STATIONS DIAGRAM (SEFZAL NOS. 2001 AND UP) 

LAC SERIALS 2001 AND UP 
AC 20-64 

8/l/69 

Appendix 4 

page 3 

, 

FIGURE D-3. FUSELAGE CONTOUR COORDINATES 

FUS StA 42 TO FUS STA 217 - BRWEEN THESE STATIONS THE FUSELAGE 

IS A FAIRED SECTION. THE CONTOUR SHOULD CONFORMTO THE SURROUNDING STRUCTURE. 

FUS STA 217 TO FUS StA 901 - CONSTANT SECTION AS SHOWN. OUTER-SURFACE 

CONTOUR IS GIVEN; SUBTRACTSKIN THICKNESS tSEE.53~2-1, FIGURE 11 TO 

OBTAIN FRAME, FORMER OR BULKHEAD CONTOUR. 

FUS StA 901 TO FUS StA 1117 - SEE TABLE 

FOR VALUES OF DIMENSIONS AT APPROPRIATE 

FUSELAGE STATION. 

POINT 

SYMMElR I CAL 

r I 

POINT “A” POINT “8” POINT “C” I I 

FUS STA X Y ’ RIJ 

I 

B.L. W.L. B. 1. w. 1. B.L. W.L. 

Rs ) RL 

! 

907. a G .25 -13 149.96 64.94 129.83 28.23 88.19 68.00 61.861 

44.42 103.63 1 67.19 I 

1015 15.99 6:43 152.94 62.91 143.09 31 

1024.5 4.97 17.16 5.87 153.82 61.62 142.96 28.75 

1034 588 

6:22 

17.99 5 25 

SInn 

Ma1 60.40 143.60 26.07 102.53 

1037.5 lB2n Ma 19 59.92 143.86 25.10 102. a4 61.18 1 56. 

1053 7.711 lo& 74 59.12 I 55. 

--_-- 

___._. 

_.__ -- -___- i IU.UL 

---- , 18.55 J:ii 156.97 iai ii 146. a3 21.58 ____. , __~ , -..:i 1 67.36 

1063.7 18. ia 3.19 56 79 149.15 19.71 106.41 57.59 54.36 64.84 

r 

a73 158.19 1 

1072 9.52 17.53 2.73 159.08 55164 150.47 19.21 108.07 1 56.37 53.60 62.48 , 

I 1117 13.83 13. a3 0 163.83 - - - - ] 48.96 48.96 48.96 I 

NOTE 

1. DATA GIVEN FOR OUTER-SURFACE CONTOUR. SUBTRACT SKIN THICKNESS 

(SEE 53-2-1, FIGURE 11 TO OBTAIN FRAME, FORMER OR BULKHEAD CONTOUR. 

2. BETWEEN FUS STA 1072 AND 1117 THE FUSELAGE IS A FAIRED SECTION. 

THE CONTOUR SHOULD CONFORMTO THE SURROUNDING STRUCTURE. l 

FUS STA 1117 TO FUS StA 1295 - BElWEEN THESE STATIONS THE FUSELAGE 

IS A FAIRED SECTION. THE CONTOUR SHOULD CONFORMTO THE SURROUNDING 

STRUCTURE. 
Appendix 4 

Page 4 

FIGURE D-4. FUSELAGE CANTED SECTION 

AC 20-64 

8/l/69 

NOTE 

-- 

-- -------W.L.184 

TAIL SECTION 

REFERENCELINE 

A. FRAME OR FORMER SEGMENTS 

ARELOCATEDAPPROXIMATELY 

AS SHOWN:- 

INGER NOS 

VIEWLOOKING FORWARDATATYPICAL FRAME 

B. PORTIONOFFRAMEORFORMER SEGMENT IS INDICATED WHERE 

NECESSARYAS FOLLOWS: 

*INNER FLANGE 

+OUTERFiANGE 

.WEB 

C. REFER TO53-2-3,FlGURE 2 FOR REPAIRS AND NEGLIGIBLE DAMAGE. 

IF NOT APPLICABLE,REFER TO51-3-6,FlGURE l(SHEElS 1AND 21. 
AC 20-64 

8/l/69 

Appendix 5 

Page 1 

FIGURE E-l. STABILIZERS STATIONS DIAGRAM 
Appendix $ AC 20-64 

Page 2 81 l/69 

FXGUF,E E-2. HORIZONTAL STABILIZER STRINGER IDENTIFICATION 

STA 

280 . STA STA STA STA STA STA STA 

2:‘~“~ ‘,i’ 2ST$o 

v:/; 

Yiv 

1; III 

4-- LOWER SURFACE 

FOR REPA IRS: 

IN AREA MARKED THUS fSil3.NOTE ITEMS INDICATED THUS + IN CALLOUTS BELOW. 

IN AREA MARKED THUS D,NOTE ITEMS INDICATED THUS * IN CALLOUTS BELOW. 

IN AREAS IMARKED THUS &Z3. NOTE ITEMS INDICATEDTHUS + IN CALLOUTS BELOW 

IN AREAS MARKED THUS m. SEE SHEET 2. 

THIS TYPE REPAIR MAY BE MADE ONLY IN THE LOCATIONS INDICATED ABOVE, ON LEFT 

AND RIGHT STABILIZERS. 

NOTE: NO REPAIR SHOULD BE ADJACENT TO, NOR CIIRECTLY OPPOSITE ( IN THE OTHER 

SURFACE, ANOTHER REPAIR OF THIS TYPE. 

1 ACCESS DOOR - MAKE FROM .05D 7D75-T6 CLAD. SHAPE TO SUIT CUT-OUT IN SKIN 

WITH MINIMUM GAP. ATTACH WITH NAS517-3 SCREWS. 

2 DOUBLER ., 4AKE FROM .050 7D75-T6 LIAD. DIMENSIONS NOT SHOWN ARE TO BE 

TAKEN FROM AIRPLANE. MAKE 4CCESS HOLE ENDS SEMI-CIRCULAR. TRIM 

FLANGE fi SHOWN FOR ANGLE.JOGGLE SIDES ON TO STRINGER fiAYGES. 

3 ANGLE - MAKE FROM .D4D 7G75-T6 CLAD, SAME LENGTIJ AS DOUBLER. TRIM ENDS AS 

SHOWN IN MAIN VIEW. OR WHERE APPLICABLE. AS IN VIEW “A’: 

4 FILLER - M4KE FROM .032 7075-T6 CLAD. TRIM ENDS ASjHOWN. 

5 SKIN ATTADMENTS: 

ROW($++FOR LENGTH OF DOUBLER, ADD MS20426AD5 RIVETS MIDWAY BETWEEN 

EXISTING RIVETS. 

*FOR LENGTH OF DOUBLER, REPLACE EXlSTlNG MS20426ADS RIVETS 

i’. rH MS2D426DD6 RIVEIS. 

ROWS~i4ND@- IN AREA OF CUT-OUT IN SKIN ADD ANCHOR NUTS (SAME 

TYPE AS ITEM 71 MIDWAY BRWEEN MS20426AD5 RIVETS REPLACED IN EXISTING HOLES (COUNTERSUNK IN STRINGER 

FLANGES 1. 

OUTSIDE AREA OF CUT-OUT IN SKIN, REPlACE 3 EXISTING 

RIVETS WITH MS20426DD6 RIVETS. 

ROWS@AND@- MQD426DD6. USE 3 IN EACH ROW, SPACED 1.00 APART EACH 

SIDE OF DAMAGE. 

ROWS@ AND@ - MS20426DDb. USE 3 IN EACH ROW, SPACED 1.10 APART EACH 

SIDE OF DAMAGE. 

ROW@ ++RETAIN ORIGINAL RIVETS. 

+FOR LENGTH OF DOUBLER ADD MS2D426ADS RIVETS MIDWAY BETWEEN 

EXISTING RIVETS. 

5 STEM AnACHMENTS - AN470ADS. SP4CE 1.00 APART. 

7 ANCHOR Nlll5 (l*‘I’%!ER AS REO) - NAS6BDA3. POSITION AROUND PERIPHERY OF CUT8 CUT-OUT Ih C’ u4KE ENDS SEMI-CIRCULAR. 

9 ADJACENT RI’; 

lG ORIGINAL SKIN 

11 ADJACENT STRINGERS 

12 EXISTING STRAP ON ADJACENT STRINGER l WHERE APPLICABLE). 
NUMBER 

STA 

0.0 

\)J2 /\, 

STA STA STA 

53.5 67.0 121.0 

I I I 

ACE 

SYh'UkTRICAL 

ABOUT i OF AtRPLANE 

2 

MOTE 

A. FOR LilCATlON OF AU RIBS, 

SEE 554, FIGURE 1, 

8. LEllERS INDICATE APPLICABLE 

REPAIR TYPE AS SHOWN ON 

Fl GURE 2. 

10 

STRINGER -,071 7075-76 CLAD,SEE51-3-6, FIGURE1 ISHEm 11 AND 51-3-7, 

FIGURE1 ISHEET 

STRINGER -.050 7075-T6 CLAD, SEE51-3-6, FIGURE 1 (SHEET11 AND X-3-7, 

FIGURE 1 (SHEET21 

STRINGER -LS6658, SEEFlGURE2 

STRINGER -LS6T18,SEEFIGURE2 

STRINGER -LS6777, SEEFIGURE 

STRINGER -LS6659,SEEFlGURE2 

S'TRINGER -LS67%,SEEFlGURE2 

STIFFENER -.D40 2024-14 CLAD, SEE 51-3-6, FIGURE 16HEfll) 

STIFFENER -LS688ltTYPlCALEXfZEPTAS SHOWN),SEESl-3-6, FIGURE 1 

(SHEET 2) 

STIFFENER -LS3505, SEE 51-3-6. FIGIJREI (SiifEi.2) 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 1 

APPENDIX 6. MAINTENANCE NOTES FOR WING STRUCTURAL AREAS 

1. INTRODUCTION. These maintenance notes have been compiled to assist L-188 

series aircraft owners/operators in maintaining the wing of their 

airplanes for a long and useful service Life. Summarized herein are 

structural areas of the wing which have shown need for special 

inspections and/or maintenance during the service history of the L-188 

fleet. Types of discrepancies which may be found, the locations, and 

corrective action measures are listed. The purpose of this information 

is to acquaint maintenance planning personnel with specific areas of 

the wing which should be included in an overall wing inspection/ 

maintenance program. 

This documentation has been assembled for reference usage and is 

not intended to replace nor be used in lieu of any maintenance/ 

inspection material or manual. Detail methods for inspections, maintenanc 

and repairs/reinforcements are contained in these existing documents 

and in the service bulletins referenced herein. 

Direct assistance for your maintenance/inspection activities can 

be obtained by contacting the aircraft manufacturer. 

2. SERIAL NUMBER (S/N) CODING FOR AIRCRAFT. 

a. 1001, 1002, 1004, thru 1148, 2001 thru 2022. 

b. 1002, 1004 thru 1043, 1045 thru 1120, 2001 thru 2012. 

C. 1001, 1002, 1004 thru 1056, 1058, (Right Wing Only), and 1059 thru 

1069. 

3. LOCKHEEDSTRUCTURAL SERVICE BULLETIN INDEX. 

88/SB-334 - Wing - Wing Leading Edge Attaching Screws - Replacement Of 

88/SB-564 - Wing - Inspection of Wing Plank Depressions 

88/SB-587 - Wing - No. 4 Wing Plank - Inspection Of 

88/SB-591 - Wing - Flap Track Attaching Bolts - Inspection Of 

88/SB-593 - Wing - Main Landing Gear Actuating Cylinder Attach Fitting 

Intercostal - Inspection Of 

88/SB-599 - Wing - Main Landing Gear Actuator Support Fittings - Inspection Of 

88/SB-600 - Wing - Upper Skin Planks - Inspection and Repair of 

88/SB-616 - Wing - Upper 6r Lower Access Door Lands - Inspection.Of 

88/SB-619 - Wing - Upper Surface at W.S. 167 and W.S. 209 - 

Reinforcement 

88/SB-620 - Wing - Wing Plank Splices Corrosion and Stress Corrosion 

Cracks - Inspection and Repair Of 

88/SB-625 - Wing - Wing Plank Splices Aft of Main Landing Gear Fulcrum 

Fittings - Inspection Of 

88/SB-628 - Wing - Corrosion of Wing Panels at Centroid Risers - 

Prevention Of 

88/SB-631 - Wing - MLG Ribs - Inspection and Rework Of 

Par 1 
Appendix 6 AC 20-64 CHG 1 

Page 2 10/26/73 

88/SB-632 - Wing - Upper Surface Cracks at Fastener Holes - Inspection 

and Repair Of 

88/SB-633 - Wing - Outer Wing to Center Wing Attach Fittings - Inspection 

Of 

88/SB-634 - Wing - Upper Surface Cracks at Trailing Edge - Inspection 

and Repair - W.S. 143 

88/SB-638 - Wing i Wing to Nacelle Attachment Plates - Inspection and 

Repair Of 

88/SB-639 - Wing - Main Landing Gear Rib Caps - Inspection and Rework Of 

88/SB-649 - Wing - No. 1 and No. 2 Upper Plank Surface Cracks at 

Nacelle Fillet Attachment - Inspection and Repair Of 

88/SB-652 - Wing - Cracks in No. 3 Upper,Wing Panel at W.S. 346 - 

Preventive and Repair Of 

88/SB-653 - Wing - Plank No. 1, Lower Attachment to Spar Cap, W.S. 

205-275 - Repair or Reinforcement Of 

88/SB-654 - Wing - Rear Beam Clip Inspection - W.S. 179/197 

88/SB-655 - Wing - Trailing Edge Rib Panels - Repair and Preventive 

Reinforcement 

88/SB-665 - Wing - Upper Plank No.1, W.S. 168 to W.S. 174, and Upper 

Forward Spar Cap, W.S. 156 to 178 - Preventive Reinforcement 

and Repair Of 

88/SB-669 - Wing - Repair for Cracks in Wing Lower Surface, Planks Nos. 1 

thru 8, W.S. 157 to 219 

88/SB-670 - Wing - Crack in Upper Forward Spar Cap Vertical Leg at W.S. 

168 - Repair and Preventive Reinforcement 

88/S&675 - Wing - Upper Surface - Repair of Wing Plank Nos. 2 to 4 on 

Each Side of Inboard Nacelles 

88/SB-676 - Wing - Preventive Reinforcement of Upper Planks 1 thru 5 

at Inboard Side of Outboard Nacelle 

88/SB-678 - Wing - Center Section - Corrosion Repair at B.L. 65 L/R 

88/SB-682 - Wing - Upper Surface - Repair for crack in Upper Forward 

Spar Cap and Web at W.S. 209 

88/SB-685 - Wing - Corrosion Around Splice Fasteners, Rework and Repair 

4. SERVICE INFORMATION LETTERS (SILs). 

a. 88/SIL-58 Inspection of Wing Planks Under Wing to Fuselage 

Fillets and Lavatory Drain Valve 

b. 88/SIL-61 Inspection and Repair of Wing Lower Skin Planks 

c. 88/SIL-87 General Structures - Sealants for Fuel Sealing, 

Pressurization Sealing, and Corrosion Protection 

Par 3 
AC 20-64 CHG 1 

10/26/73 

FUEL PROBES 

ACCE 

SECTION A-A 

FdEL PROBE 1 

VERTICAL CRACK 

i 

1 I 

! 

I 7 0 

z / 6 I 0 I 

, 
INBOARD NACELLE 

SKATE ANGLES 

ACCESS DOORS 

1 \ I L 

&ii A, & &y&x!;~ (!$ &, b&g & fi;; 

18 8,,/ 

UPPER PANEL LH 

LOOKING DOWN INBD 
Appendix 6 

Page 3 (and 4) 

UPPER PANEL RH 

LOOKING DOWN 

IDENTIFI 

OUTBOARD NACELLE 

SKATE ANGLES 

\ NUMBER 

FRONT SPAR 1 

NOTE: LH AND RH WING 

IDENTIFICATIONS 

ARE THE SAME 

FUEL PROBE 

. @ co; 

WING SECTD’J 

4 

UPPER SURFACE 

CATION 

FWD 

FIGURE F-l. Wing Section Upper Surface 
AC 20-64 CHG 1 

10/26/73 

LEAP DOUBLER - 

ACCESS DOORS 
LEAP DOUBLER 

FRONT SPAR - 

IINBD 

FWD 

0 / 

n ! FUEL QUANTITY GAGE 

LOWER PANEL RH 

VIEW LOOKING UP 
Appendix 6 

Page 5 (and 6) 

I 

Jl 

I 

9 

QUANTITY GAGE 8 I 

0 

\ 

:\ 0 I 7 

eY----Y------ 

I 

6 I 

I 

‘0 

a 

III 0 4 I 

JPPER PANEL LH 

mOOKING DOWN HORIZONTAL 

CRACK 

1 PLANK 

IDENTIFICATION 

NUMBER 

ID NACELLE 

\IGLES 

-REAR SPAR 

VERTICAL 

CRACK 

SECTION A-A 

TYPICAL PLANK SPLICE 

CRACK ORIENTATION 

NOTE: LH AND RH WING 

I DENTI FICATIONS 

ARE THE SAME 

D 

+-l FWD 

WING SECTION 

LOWER SURFACE 

FIGURE F-2. Wing Section Lower Surface. 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 7 

FIGURE F-3. SERVICE PROBLEM AREAS 

Pages 8 through 27 (and 28) refer to various service problem 

areas and are cross-referenced to the photographs in figures 

Figures F-4 through F-32. 
Appendix 6 AC 20-64 CHG 1 

Page 8 10/26/73 

1 2 3 4 5 6 

NO. 

W-l 

w-2 

w-3 

w-4 

MAJOR 

ASSEMBLY 

Outer Wing Leading 

Edge Inboard, 

Middle, & Outboard 

Sections 

Outer Wing Lower 

Surface 

Outer Wing Lower 

Surface, W.S. 159.6 

&rter Wing Lower 

Surface 

ITEM 

Attach 

Screws 

Upper and 

Lower 

Vo. 1 and 3 

glan ks 

IO. 4 Plank 

dear Spar 

SERVICE HISTORY 

Loosening has occurred of the 

screws attaching the .leading 

edge skins to the front spar 

caps. 

Surface depressions have been 

reported in planks between 

Wing Stations 478 and 528. 

Cracks have occurred at the 

lower No. 4 wing plank drain 

hole adjacent to Wing Station 

159.6. 

Loose and failed flap track 

attachment bolts have been 

found. 

PAGE 

REF. 

FOR 

ILLUST. 

29 

30 

31 

32 

33 

S/N 

CODE 

A 

n 1 

n 1 

n 1 
AC 20-64 CHG 1 

10/26/73 

7 

METHOD 

OF 

INSP. 

Visual 

Visual 

Externa I 

Visual 

Visual 

FREQUENCY 

OF 

INSPECTION 

Inspect at 50 flight hours intervals 

and retighten all screws each 300 

hours until LAC 88&B-334 is 

incorporated. 

Inspect within next 300 hour 

i n terval. If depressions exceed 

limits reinspect each 100 hours 

until corrective action is taken. 

Repeat inspections at 1000 hour 

intervals until permanent repair is 

incorporated. Interim repairs have 

special inspection requirements. 

Inspect’ within 850 hours and 

reinspect at 5000 hour intervals. 

8 9 

RECOMMENDATIONS 

TYPE OR METHOD 

OF 

REPAIR 

Remove existing screws and 

replace with new type fasteners 

per 88/SB-334. 

Replace H-clips per instructions 

of LAC Service Bulletin 

88/SB-564. 

(1 1 Preventive/temporary 

repair may be effected by 

installing 5/16 Hi-Lok fasteners 

in drain holes per 88/SB-587C 

with continued 1000 hr. repeat 

inspections. 

( 2 ) Permanent 

repair/reinforcement can be 

made by incorporating either 

SED/63-9015-101 or 

SE D/63-901 5-l 35 shown on 

Dwg. SE D/63-901 5B. 

Replace and/or tighten bolts 

and rework bolt holes per LAC 

88/SB-591 A. 

f 

Appendix 6 

Page 9 

10 

PREVENTIVE 

ACTION 

Accomplish 

88/SB-334. 

Same as Column 9. 

Same as Column 9, 

Item (2). 

Same as Column 9. 
Appendix 6 AC 20-64 CHG 1 

Page 10 10/26/73 

1 

NO. 

w-5 

W-6 

2 

MAJOR 

ASSEMBLY 

Outer Wing Lower 

Surface, W.S. 

179-197 

Outer Wing Lower 

Surface,W.S. 187 

3 

ITEM SERVICE HISTORY 

fling Plank 

No. 7 

support 

F itting, M LG 

Actuator 

‘/N800618-’ 

VN 8006 18-: 

VN 8006 18-: 

‘/N 800618-l 

4 

Cracks have occurred in the 

wing plank surface and plank 

riser located under the main 

landing gear actuating cylinder 

attach fitting angles, P/N 

802699. 

Fatigue cracks have occurred at 

the aft end of the MLG actuator 

support fittings in the radius 

of the vertical legs. 

5 

PAGE 

REF. 

FOR 

ILLUST. 

34 

35 

35 

36 

6 

S/N 

CODE 

A 1 

A 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 11 

7 

METHOD 

OF 

INSP. 

Visual 

Requires 

removal of 

801266-l 

door (Dry 

Bay A/C) 

& 800917 

Door (Wet 

Bay A/C) 

Visual, Dye 

Penetrant 

FREQUENCY 

OF 

INSPECTION 

Within next 2500 flight hours 

on A/C which have 88/SB-538 

incorporated. Otherwise, inspect 

at 88/SB-538 incorporation, or 

within next 2500 flt. hours, 

whichever occurs first. 

Repeat inspections at 2500 fit. 

hour intervals are recommended. 

Dye penetrant i nspec t original 

800618-3 & -4 fittings within 215 

flight hours* Repeat at 

425 flt. hrs. Visual dye 

penetrant inspect aft 4 in. of 

fittings at each 850 flt. hrs. 

Visual inspect reworked fittings 

(radius on aft edge) at each 850 

flt. hrs. and dye penetrant 

inspect at each 1700 flt. hrs. 

No repeat inspections for new 

841275-101, -102 fittings. 

TYPE OR METHOD 

OF 

REPAIR 

8 9 

RECOMMENDATIONS 

Repair wing plank skin and 

riser cracks per Electra 

Structural Repair Manual, 

Section 57-2-1, Fig. 3, 

Sheets 41 thru 44, LAC 

Dwg. 841880, and LAC 

88/SB-593C. Repair 

out-of-round holes per LAC 

Service Bulletin 88/SB-593C. 

Install new 800618-3 or 

841275-101 (LH) and 

800618-4 or 841275-102 (RH) 

support fittings to replace 

damaged parts per LAC 

88/SB-599A. 

10 

PREVENTIVE 

ACTION 

Same as Column 9. 

Install new fittings, 

P/N 841275. 
Appendix 6 

Page 12 

1 

NO. 

w-7 

W-8 

2 

MAJOR 

ASSEMBLY 

3uter Wing Upper 

Surface 

3uter Wing Upper 

md Lower Surfaces 

3 

ITEM 

Ying Planks 

under 

iacelle 

kate angles 

‘uel Tank 

Access 

Ioor Lands 

4- 

SERVICE HISTORY 

Cracks up to three inches in 

length have occurred under the 

inboard and outboard skate 

angles of the inboard nacelle. 

Corrosion has been reported on 

lower wing plank access door 

lands due to condensation. 

AC 20-64 CHG 1 

10/26/73 

5 

PAGE 

REF. 

FOR 

ILLUST. 

37 

38 

6 

S/N 

CODE 

n 1 

A 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 13 

7 

METHOD 

OF 

INSP. 

Visual 

(External, 

Internal) 

X-Ray 

Visual 

f 

8 9 

RECOMMENDATIONS 

FREQUENCY TYPE OR METHOD 

OF 

INSPECTION 

OF 

REPAIR 

Initial external inspection at 450 

flt. hrs. with repeat at next 450. 

Initial internal inspection at 900 

flt. hrs. with repeat at 3000 hr. 

intervals. Discontinue inspections 

after 6000 hrs. if no cracks found. 

Within next 850 flt. hrs. 

Reinspect at each overhaul 

period. 

(1) Repair cracks in planks per 

Electra Structural Repair 

Manual, Section 57-2-l. 

(2) Install skate angle 

attachment reinforcement at 

inbd. and outbd. nacelles per 

LAC Alert Service Bulletin 

88/SB-600A (Ref: LAC Dwg. 

841481). 

Remove corrosion per Electra 

Structural Repair Manual 

Section 51-2-14 and add 

protective coating per LAC 

Service Bulletin 88&B-606. 

Repair per LAC Drawing 

841295 when damage exceeds 

.OlO inch depth. 

NOTE: Contact LAC for 

repair of damage which exceeds 

allowable limits of Dwg. 

841295. 

( Refer to 88/SB-620G for 

access door gap sealing 

instructions.) 

10 

PREVENTIVE 

ACTION 

Same as Column 9, 

Item (2). 

Add protection per 

88/SB-606. Refer 

to 88/SB-620G for 

access door gap 

sealing 

instructions. 
Appendix 6 

Page 14 

1 2 3 4 5 6 

NO. 

w-9 

w-10 

W-l 1 

MAJOR 

ASSEMBLY 

Outer Wing Upper 

Surface, W.S. 167 & 

W.S. 209 

Center Section Wing, 

Outer Wing 

Outer Wing Lower Wing Plank 

Surface, W.S. 167 & Nos. 3,4,5, 

W.S. 209 & 6. 

ITEM 

Wing Planks 

at MLG Rib 

Forgings 

SERVICE HISTORY 

Cracks have occurred in the 

wing upper surface in the area 

of the MLG rib forgings. 

Wing Planks Corrosion and cracks have 

Upper and occurred at various locations in 

Lower the upper and lower wing plank 

Surfaces splices. 

Cracks have occurred in the 

lower wing No. 5 plank of the 

LH inboard MLG fulcrum 

fitting at the No. 4 and No. 5 

splice; also, at a fastener hole in 

plank No. 6 at approx. W.S. 

211. 

AC 20-64 CHG 1 

IO/26173 

PAGE 

REF. 

FOR 

ILLUST. 

39 

40 

30 

37 

38 

41 

42 

43 

44 

S/N 

CODE 

n 1 

n 1 

A 1 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 15 

7 

METHOD FREQUENCY TYPE OR METHOD 

OF OF OF 

INSP. INSPECTION REPAIR 

Visua I 

and d y e 

penetrant. 

U I t rasonic 

and X-Ray 

may be used 

in local 

areas. 

Visual, Repeat inspection intervals As specified in LAC Service 

U I trasonic based on action taken. Bulletin 88/SB-620G. 

Dye 

Penetrant, 

U I trasonic 

f 

8 9 

RECOMMENDATIONS 

Initial inspection Install 0.063 inch thick 

within 700 landings doublers under existing 

with repeat inspections at 1400 external doublers and install 

landing intervals. No repeat angle stiffeners on the wing 

inspections required after internal surface at the Plank 

incorporation of reinforcements No. 3 & No. 4 splice on A/C 

described in LAC Service Bulletin S/N 1001, 1002, 1004 thru 

88/SB-619. 1144, and 2001 thru 2019. 

Initial inspection 

within 700 landings 

with repeat inspections at 1400 

landing intervals. Repetitive 

inspections may be discontinued 

after incorporation of LAC 

Service Bulletin 88/SB-625 

reinforcements. 

Install new external doublers 

only on A/C S/N 1145 thru 

1148 and 2020 thru 2022. 

Accomplish rework per LAC 

Service Bulletin 88/SB-619A. 

Ref. LAC Drawings 841314C, 

84 13 15C, 841345, 841346, 

SE D/64-9010, SED/64-9011. 

As specified in LAC Service 

Bulletin 88/SB-625D. 

Seal plank splices under repairs 

per 88/SB-620G. 

f 

10 

PREVENTIVE 

ACTION 

Same as Column 9. 

Accomplish 

Service Bulletin 

88/SB-620G. 

Same as Column 9. 
Appendix 6 

Page 16 

AC 20-64 CHG 1 

10/26/73 

1 

NO. 

w-1; 

w-13 

w-14 

w-15 

2. 

MAJOR 

ASSEMBLY 

Outer Wing Upper & 

Lower Surfaces 

W.S. 155 

W.S. 221 

Outer Wing Upper 

Surface, W.S. 167 81 

W.S. 209 

Outer Wing Lower 

Surface 

W.S. 128 

W.S. 193 

W.S. 266 

Outer Wing Upper 

Surface 

vV.S. 2 12-230 

e 

- 

3 

-- 

4 

ITEM SERVICE HISTORY 

Centroid Corrosion has occurred in the 

R iser centroid riser cavities under the 

Cavities plastic fillers. 

VlLG Rib 

iNeb Fillets 

Cracks have occurred in web 

fillets at rib truss and upper 

chord member junctures. 

Ning Plank 

vos. 2,3,4. 

Cracks have occurred at the 

fastener holes around the fuel 

sight gage and fuel overflow 

openings on LH and RH lower 

wing planks. 

Ning Plank 

10. 2 

Cracks have occurred at screw 

holes in the No. 2 plank at the 

plank No. 1 and No. 2 splice 

between W.S. 212 and 230. 

5 

PAGE 

REF. 

FOR 

ILLUST. 

32 

45 

34 

46 

47 

48 

39 

6 

S/N 

CODE 

A 1 

A 1 

n 1 

0 1 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 17 

7 

METHOD 

OF 

INSP. 

Visual 

Dye 

P e netrant 

Visual, Dye 

Penetrant 

Visual, Dye 

Penetrant 

FREQUENCY 

OF 

INSPECTION 

8 9 

RECOMMENDATIONS 

TYPE OR METHOD 

l---- 

OF 

REPAIR 

At normal maintenance inspection 

interval . 

Accomplish within next 1000 

landings. 

Initially at 500 hrs. 

Repeat at 1000 hours. 

No repeat after incorporation of preventive 

repair. 

Initially at 500 hrs. 

Repeat at 1000 hours. 

No repeat after incorporation of preventive 

repair. 

Remove plastic fillers and 

metallic washers, and remove 

any corrosion present in 

accordance with instructions 

contained in LAC Drawing 

841444. Repair per Dwg. 

841443, if required. 

Install new aluminum fillers as 

shown on Dwg. 841332, and 

washers, P/N 841326-101, per 

LAC Service Bulletin 

88/SB-628B. 

Inspect, rework and repair per 

LAC Service Bulletin 

88/SB-630 and Dwg. 841374. 

Type A repair where cracks 

have not entered risers. Type B 

repairs where cracks extend 

thru risers. Ref: LAC Dwg. 

841336C and 88&B-631B. 

Install appropriate doubler per 

LAC Dwg. 841364A. Ref: LAC 

88/SB-632A. 

10 

PREVENTIVE 

ACTION 

Install aluminum 

fillers per 

88/SB-6288. 

Per LAC Dwg. 

841374 

Ref: 88/SB-630. 

Per LAC Dwg. 

8413718 

Ref: 88/SB-631B. 

Install 841364-109 

spacer and Hi-Lok 

fasteners per LAC 

88/SB-632A. 
Appendix 6 

Page 18 

AC 20-64 CHG 1 

10/26/73 

1 

NO. 

W-16 

w-17 

W-18 

w-19 

2 

MAJOR 

ASSEMBLY 

W i ng Joint-Center 

Sec. to Outer Wing 

Outer Wing-Trailing 

Edge Upper Surface 

W.S. 143 

Outer Wing Lower 

Surface 

W.S. 167 & 

W.S. 209 

Outer Wing Upper 

and Lower Surface 

W.S. 167 & 

W.S. 209 

3 

ITEM 

Attachment 

Fittings P/N 

807352 and 

P/N 807354 

Upper 

Plank Nos. 

6,7, & 8. 

fling-toNacelle 

4 ttachment 

Plate, 

P/N 810053- 

P/N8 10053-: 

P/N81 0054-’ 

P/N81 0054-c 

M a i n 

Landing 

Gear Rib 

Caps 

4 

SERVICE HISTORY 

Fatigue cracks have occurred, 

emanating from the barrel-nut 

access holes of the outer wing 

front cap fittings at B.L. 65. 

Cracks have occurred in the 

trailing edge of Wing. Planks 

Nos. 6, 7, & 8 at W.S. 143, left 

and right upper surfaces, and in 

backup fitting, P/N 803900, for 

the flap track attachment. 

Cracks have occurred in the 

attachment plate which is 

located in the inboard nacelle 

on the lower front beam of the 

left wing assembly. 

Cracks have occurred in the 

vertical legs of the MLG rib 

caps. 

5 

PAGE 

REF. 

FOR 

IL LUST. 

49 

34 

50 

51 

52 

6 

S/N 

CODE 

A _1 

A 1 

n 1 

n 1 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 19 

7 

METHOD 

OF 

INSP. 

Visual, Dye 

Penetrant 

Visual 

Visual 

I n ternal 

Visual 

f 

8 9 

RECOMI 

FREQUENCY 

OF 

INSPECTION 

Initial inspection 

within 1100 flight 

hours for cracks in lower fittings. 

Within next 3000 flt. hours 

inspect for cracks and burrs in 

both upper and lower fittings. 

Deburr all fittings within the 4100 

flt. hours limit. 

Initial inspection within 500 Repair cracks per LAC Dwg. 

landings. No special repeat 841390, or the Electra 

inspection required after Structural Repair Manual, in 

i n corporation of repair or accordance with LAC Service 

preventive reinforcement. Bulletin 88/SB-634B. 

Inspect within next 700 landings. Replace attachment plate in 

Repeat inspections every 2000 accordance with LAC 

landings until plate is replaced. 88/SB-638B. 

Inspection recommended within 

700 landings and repeat 

inspections at overhaul periods. 

Interim action requires inspection 

at each 120 landings for maximum 

of 500 landings. 

ENDATIONS 

TYPE OR METHOD 

OF 

REPAIR 

(1) Replace any cracked 

fittings before further flight, 

with new fittings deburred per 

LAC 88/SB-633B. 

(2) Deburr all untracked 

fittings having burrs, per LAC 

88/SB-633B. 

Interim action consists of stop 

drilling crack in accordance 

with LAC Service Bulletin 

88/SB-639 and Electra 

Structural Repair Manual. 

Accomplish repair in 

accordance with 88/SB-639. 

Ref: Dwgs. SED/66-9101 and 

SE D/66-91 07. 

f 

10 

PREVENTIVE 

ACTION 

Same as Column 9, 

Item (2). 

Incorporate 

preventive 

reinforcement per 

LAC Dwg. 

B41505. Ref: 

88/SB-634B. 

Install new 

attachment plates, 

P/N 84 1656-101 

or 841438-101. 

Accomplish intent 

of repair per 

B8/SB-639, 

drawings 

SED/66-9101 and 

SED/66-9107. 
Appendix 6 

Page 20 

AC 

10 

20-64 CHG 1 

26/73 

1 

NO. 

w-20 

w-21 

w-22 

W-23 

MAJOR 

ASSEMBLY 

Outer Wing Upper 

Surface 

Outer Wing Upper 

Surface 

W.S. 101-137, 

257-275, 

275-329, 

and 346 

Outer Wing Lower 

Surface 

W.S. 75-l 53, 

223-329, 

and 385 Outbd. 

Outer Wing Upper 

and Lower Surfaces 

W.S. 179 

W.S. 197 

- 

3 

ITEM 

Wing Planks 

Nos. 1 & 2 

Wing Plank 

vo. 3. 

Ning Plank 

\Jo. 1 

qib Attach 

Ilips 

‘/N OS: 

SO5483-U-2 

30549 1 - l/-2 

305482-3/-4 

305492- l/-2 

4 

SERVICE HISTORY 

Cracks have occurred in the No. 

1 Plank at the nacelle fillet 

attachments at the inboard side 

of all four nacelles. 

Cracks have occurred in No. 3 

upper wing panel along the first 

row of fasteners adjacent to the 

skate angle of the outboard 

nacelle. 

Cracks have occurred in Plank 

No. 1 from forward edge 

attachment holes. 

Cracks have occurred in the rib 

clips located at the rear beam 

forward face upper attachment. 

5 

PAGE 

REF. 

FOR 

ILLUST. 

29 

30 

53 

53 

54 

46 

6 

S/N 

CODE 

A 1 

A 

A 

A 
AC 20-64 CHG 1 Appendix 6 

10/26/73 Page 21 

7 

METHOD 

OF 

INSP. 

Visual, Eddy 

Current, Dye 

Penetrant 

V isuai 

inspection 

for cracks. 

E d d y 

current or 

X - r a y 

optional. 

Visual 

and D y e 

Penetrant 

Visual Dye 

Penetrant 

8 9 

RECOMMENDATIONS 

FREQUENCY 7 TYPE OR METHOD 

OF OF 

INSPECTION I REPAIR 

Initial inspection 

within 400 flight hours, 

Repeat inspections at intervals not 

to exceed 1400 flt. hours until 

preventive reinforcements are 

incorporated. 

Initial inspection within 700 flt. 

hrs. unless previously inspected 

within 350 hrs. Repeat at normal 

structural maint. i nspection 

intervals until preventive 

reinforcement is incorporated. 

Initial inspection within 1000 

flight hours of Service ! ,etrn 

issue unless previously inspected 

within 500 hours. 

Repeat inspections at 4000 hour 

intervals until preventive 

reinforcement is installed. 

‘.n aircraft having 10,000 flight 

hours or more, inspect in next 700 

hours. Repeat inspection at 

standard structural inspection 

interval. 

Type A, Type B, Type C and 

Type D repair, as appropriate, 

in accordance with LAC 

Service Bulletin 88/SB-649B. 

(1) Repair cracks in wing panel 

per Dwg. 841507B. 

(2) Repair cracks around 

access doors per Dwg. 

841655A. 

Repair in accordance with LAC 

Service Bulletin 88/SB-653A 

and Dwg. No. 841441B Repair 

Installation Nos. 841441-175, 

-176, -177, -178, -179, -180, 

-193, -195, and -196. 

(1) Rework existing clips in 

accordance with Dwg. 841509. 

(2) Install replacement clips 

per Dwg. 841509 in accordance 

with LAC Service Bulletin 

88&B-654. 

10 

PREVENTIVE 

ACTION 

Type A, Type B, 

or Type C repairs 

and reinforcements 

or 88/SB-675 

reinforcement. 

Service Bu I letin 

88/SB-652C, 

paragraph 2E. 

Ref: Dwg. 

8415078. 

Service Bulletin 

88/SB-653A, 

paragraph 2C. (1). 

I nstal lation No. 

841516-137. 

Same as Column 9, 

Item (2). 
AC 20-64 CHG 1 

App end ix 6 

Page 22 

1 

NO. 

W-24 

W-25 

2 

MAJOR 

ASSEMBLY 

Outer Wing Trailing 

Edge, Flap Stations 

125 to 331 

Outer Wing Upper 

Surface 

W.S. 156-l 78 

- 

3 

ITEM 

Trailing 

Edge Skin 

Panels, 

Trailing 

Edge Ribs. 

Upper 

Plank No. 1 

W.S. 168-17L 

Upper 

Forward 

Spar Cap 

W.S. 156-l 7E 

4 

SERVICE HISTORY 

Loose fasteners and cracks have 

occurred in the wing trailing 

edge skin panels and trailing 

edge rib webs and flanges. 

Cracks emanating from the 

leading edge have occurred in 

the No. 1 upper planks inboard 

of the No. 2 and No. 3 nacelles. 

Cracks have occurred in the aft 

tang of the upper front spar cap 

emanating from the first 

attachment hole in area of the 

inboard skate angle of the 

in board nacelles. 

10/26/73 

5 

PAGE 

REF. 

FOR 

ILLUST. 

36 

37 

40 

-G--- 

S/N 

CODE 

n 1 

n 1 
AC 20-64 CHG 1 

10/26/73 

7 

f 

METHOD FREQUENCY TYPE OR METHOD 

OF OF OF 

INSP. INSPECTION REPAIR 

Visual (from 

access holes 

to lntercostal) and 

X-ray (from 

Intercostal 

to T.E.). 

Verify 

cracks 

using D ye 

Penetrant 

(Requires 

skin removal) 

Visual, 

X-Ray 

8 9 

RECOMMENDATIONS 

Conveniently scheduled inspection 

period. 

Repeat at normal inspection 

intervals. 

4s specified in 

LAC 88/SB-665D. No. 1 plank: 

initial inspection within next 50 

Fit. hours with repeat inspections 

at intervals not to exceed 625 

Tours. Spar Cap: 1250 flt. hour 

repeat inspection intervals 

ncreasing to 2500 flt. hour 

ntervals after No. 1 plank is 

?einforced or repaired. 

special repeat inspections may be 

discontinued for No. 1 plank and 

;par cap when their Jespective 

*epa i rs or reinforcements are 

ncorporated. 

Electra Structural Repair 

Manual, Sections 57-4-1, 

51-2-14, and 51-3-g. 

Per Repair Index Dwg. 841628 

in accordance with Service 

Bulletin 88/SB-665D: 

Wing Upper Surface 

Dwg. 841580D 

8415818 

841582B 

Wing Upper Front Spar Cap 

Dwg. 841623B 

841624B 

Appendix 6 

Page 23 

f: 

10 

PREVENTIVE 

ACTION 

Service Bulletin 

88/SB-655, 

paragraph 2.C. 

Ref: Dwg. 

841512 

Per Drawing 

341628 in 

accordance with 

?8/SB-665D 

Ref: Dwg. 

341576A 

3415778 

341578A 

341579A 
Appendix 6 

Page 24 

AC 20-64 CHG 1 

10/26/73 

1 2 3 4 5 6 

NO. 

MAJOR 

ASSEMBLY ITEM SERVICE HISTORY 

PAGE 

REF. 

FOR 

ILLUST. 

S/N 

CODE 

W-26 

W-27 

W-28 

w-29 

Outer Wing Lower 

Surface 

W.S. 157 to 

W.S. 219 

0 uter Wing Front Upper Cap Cracks have occurred in upper 

Spar 3nd Spar spar cap vertical leg and in web 

W.S. 168 JVeb at rib attach bolts at W.S. 168. 

3uter Wing Upper 

Surface 

3uter Wing Upper 

Surface 

N.S. 346 

Wing Planks 

Nos. 1 thru 

8 

Ning Planks 

vos. 2 to 4 

3n each side 

Df inboard 

iacelles 

Ning Planks 

IO. 1 thru 

5 at inboard 

;ide of 

outboard 

iacel les 

Cracks have occurred in the 35 

lower wing planks in the 44 

vicinity of the Main Landing 54 

Gear ribs at W.S. 167 and 209. 55 

Cracks have occurred in upper 

wing planks 2, 3, and 4 in skate 

angle area. 

Cracks have occurred in upper 

wing planks No. 1 thru 5 at 

W.S. 346. 

50 

51 

56 

30 

A 

n 1 

A 

A 
AC 20-64 CHG 1 

10/26/73 

Appendix 6 

Page 25 

7 

METHOD 

OF 

INSP. 

Visua I 

and Dyt 

Penetrant 

Visual, Eddy 

current 

Visua I 

and Dyt 

Penetrant 

Visual 

(accomplish 

in conjunction with 

88/SB-649 

inspect ion) 

‘f 8 9 

RECOMI MENDATIC!NS 

FREQUENCY 

OF 

INSPECTION 

TYPE OR METHOD 

OF 

REPAIR 

Initial inspection within the next 

400 hours time in service unless 

previously accomplished. 

LAC Service Bulletin 

88/SB-669A for detailed 

instruct ions. 

Repeat inspections within 2500 

flt. hours or 2500 landings 

whichever comes first. 

On aircraft having 20,000 flt. 

hours or more inspect within 625 

flt. hours. Repeat inspection at 

1250 flt. hour intervals until 

preventive reinforcement or repair 

which eliminates repeat 

inspections is installed. 

Inspect within 700 flt. hours with 

follow-up inspections at normal 

structural maintenance inspection 

intervals. 

Norma I structural maintenance 

inspection interval, but in no case 

shall interval exceed that required 

by LAC Service Bulletin 

88/SB-649. 

f 

Per listed repair installations in 

accordance with LAC Service 

Bulletin 88/SB-669A. 

INSTALLATION PLANK 

No. 841634 No. 1 & 2 

841635 No. 1 

841636 No.. 3,4,5 

841642 No. 5 & 6 

841865 MLG Drag 

Strut Area 

Repair in accordance with LAC 

Service Bulletin 88/SB-670D, 

paragraph 2.E. 

DRAWINGS 

841624B 

841738A 

8417438 

841806B 

Repair in accordance with LAC 

Service Bulletin 88/SB-675 and 

Dwg. Nos. 841758 and 

841770A. 

Preventive reinforcement - S e e 

column 10 for i n s t a I I a t i 0 n 

instructions 

10 

PREVENTIVE 

ACTION 

Same as Column 9. 

Service Bulletin 

88/SB-670D, 

paragraph 2.0. 

Ref: Dwg. 

841717E 

Same as Column 9 

Install 

reinforcements per 

LAC Service 

Bulletin 

88/SB-676. 

Ref: Dwg. 

841760 
Appendix 6 

Page 26 

AC 20-64 CHG 1 

10/26/73 

1 

NO. 

w-3c 

w-31 

W-32 

MAJOR 

ASSEMBLY 

Wing Center Section 

B.L. 65 L/R 

Outer Wing Front 

Spar W.S. 209 

3uter Wing and 

Zenter Section B.L. 

I to W.S. 584 

3 

ITEM 

Upper and 

Lower Wing 

Surfaces at 

B.L. 65 

Splice Area 

Upper cap 

and spar 

web 

Upper and 

Lower Wing 

Surfaces, 

B.L. 0 to 

W.S. 584 

4 

SERVICE HISTORY 

- 

Corrosion damage has been 

reported in upper and lower 

wing surfaces at B.L. 65 where 

center section joins outer 

sections. 

Cracks have occurred in the 

spar web at the MLG rib attach 

bolts thru the rib tee, spar web, 

upper spar cap and nacelle 

attach fitting. 

Corrosion damage around plank 

splice fasteners has occurred on 

both the upper and lower wing 

surf aces. 

5 

PAGE 

REF. 

FOR 

ILLUST. 

42 

57 

51 

43 

6 

S/N 

CODE 

A 1 

n 1 

n 1 
AC 20-64 CHG 1 Appendix 6 

m/26/73 Page 27 (and 28) 

7 

METHOD 

OF 

INSP. 

Visual 

Visual, Eddy 

current 

Visual 

8 9 

RECOMMENDATIONS 

FREQUENCY 

OF 

INSPECTION 

TYPE OR METHOD 

OF 

REPAIR 

Inspect at next periodic with 

repeat inspections at every major 

structural inspection interval. 

On aircraft having 20,000 hours or 

more inspect within 625 flt. 

hours. Repeat inspection at 1250 

flt. hour intervals until preventive 

reinforcement or repair which 

eliminates repeat inspections is 

installed. 

Normal wing structural 

maintenance inspection interval, 

but in no case shall interval exceed 

that required by LAC Service 

Bulletin 88/SB-620. 

Repair in accordance with LAC 

Service Bulletin 88/SB-678A. 

Repair in accordance with LAC 

Service Bulletin 88/SB-682B, 

paragraph 2.F. 

DRAWINGS 

841802 

841804C 

Repair in accordance with LAC 

Service Bulletin 88/SB-685, 

paragraphs 2.C and 2.D. 

DRAWINGS 

841867 

841872 

10 

PREVENTIVE 

ACTION 

Periodic 

inspections and 

application of 

corrosion 

protection 

coatings. 

Service Bulletin 

88/SB-682B, 

paragraph 2.E. 

Ref: Drawing 

841800C 

Periodic 

inspections and 

application of 

corrosion 

protection 

coatings. 
AC 20-64 CHG 1 

10/26/73 

Appendix 6 

Page 29 

FS.GURE F-4. WING UPPER SURFACE 

Reference W-l, page 8 

W-20, page Ztil 
APP endix 6 

pag e 30 

AC 20-64 CHG 1 

10/26/73 

F'IGURE F-5. WING UI'PEX SURFACE 

Reference W-l, page 8 

W-10, page 14 

W-20, page 20 

W-29, page 24 
AC 20-64 CHG 1 

10/26/73 

Appendix 6 

Page 31 

Figure F-6.WING LOWER SURFACE 

Reference W-2, page 8! 
Appendix 6 

Page 32 

AC 20-64 CHG 1 

10/26/73 

Figure F-7. WING LOWER SURFACE 

Reference W-3, page 8 

W-12, page 16 
AC 20-64 CHG 1 

10/26/73 

Appendix 6 

Page 33 

Figure I?-8.WING EXTERNAL STRUCTURE 

Reference W-4, page 8 
Appendix 6 

Page 34 

AC 20-64 CHG 1 

10/26/73 
. . 

AC 20-64 CHG 1 

10/26/73 

Appendix 6 

Page 35 

FIGURE F-lO.WIJ!JG LOWER SURFACE 

Reference W-5, page 10 

W-6, page 10 

W-26, page 24 
Appendix 6 

Page 36 

AC 20-64 CHG 1 

10/26/73 

FIGURE F-11. WING UPPER SURFACE 

Reference w-6, 

w-24, 

page 10 

page 22 
AC 20-64 CHG 1 

10/26/73 

Appendix 

Page 37 

6 
Appendix 6 

Page 38 AC 20-64 CHG 1 

10/26/?3 

FIGURE F-13. WING UE'PER SURFACE 

Reference W-8, page 12 

W-10, page 14 
AC 20-64 CHG I 

10/26/73 

Appendix 6 

Page 39 

FIGURE F-14. WING UPPER SURFACE 

Reference W-9, page 14 

W-15, page 16 
Appendix 6 

Page 40 

AC 20-64 CHG 

10/26/73 
AC 20-64 CHG 1 

10/26/73 

Appendix 6 

Page 41 

FIGURE F-16. WING UPPER SURFACE 

Reference W-10, page 14 
APPen 

Page 

idix 6 AC 20-64 CHG 1 

4L m/26/73 

FIGURE F-17. WING UPPER & LOWER SURFACE 

Reference W-10, page 14 

W-30, page 26 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 43 

FIGURE F-18. WING UPPER & LOWER SURFACE 

Reference W-10, page 14 

W-32, page 26 
AP pendix 6 

Pa ge 44 

AC 20-64 CHG 1 

10/26/73 

FIGURE F-19. WING LOWER SURFACE 

Reference W-11, page 14 

W-26, page 24 
AC 20-64 CHG 1 

10/26/73 

Appendix 6 

Page 45 

FIGWE F-20. WING LOWER SURFACE 

Reference W-12, page 16 
Appendix 6 

Page 46 

AC 20-64 CHG I 

10/26/73 

FIGURE F-21. WING INTERNAL STRUCTURE 

Reference W-13, page 16 

W-23, page 20 
AC 

W 

20-64 CHG 1 

26173 

Appendix 6 

Page 47 

FIGURE F-22. WING LOWER SURFACE 

Reference W- 14, page 16 
Appendix 6 

Page 48 

AC 20-64 CHG 1 

10/26/73 

FIGURE F-23. WING LOWER SURFACE 

Reference W-14, page 16 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 49 

FIGURE F-24. WING INTERNAL STRUCTURE 

Reference W-16, page 18 
Appendix 6 

Page 50 

AC 20-64 CHG 1 

10/26/73 

IKLGURE F-25. WING EXTERNAL STRUCTURE 

Reference W-18, page 18 

W-27, page 24 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 51 

FIGURE F-26. WING EXTERNAL STRUCTURE 

Reference W-18, page 18 

W-27, page 24 

W-31, page 26 
Appendix 6 

Page 52 

AC 20-64 CH( 

10/26/73 

1 

FIGURE F-27. WING INTERNAL STRUCTURE 

Reference W-19, page 18 
AC 20-6 

m/26/7 
Appendix 6 

Page 54 

AC 20-64 CHG 1 

LO/26/73 

FIGURE F-29. WING LOWER SURFACE 

Reference W-22, page 20 

W-26, page 24 
AC 20-64 CHG 1 

10/26/73 Appendix 6 

Page 55 

FIGURE F-30. WING LOWER SURFACE 

- - ^ . Keterence W-26, page 24 
Appendix 6 

Page 56 

AC 20-64 CHG 1 

10/26/73 

FIGJRE F-31. WING UPPER SURFACE 

Reference W-28, page 24 
AC 20-64 ( 

10/26/73 

FIGURE F-32. WING UPPER & LOWER SURFACE 

Reference W-30, page 26