NO.

DATE

PAGE DATE 

### ALERT SERVICE BULLETIN

A Subsidiary of Textron Inc.

AN APPROPRIATE ENTRY SHOULD BE MADE IN TH E AIRCRAFT LOGBOOK UPON ACCOMPLISHMENT

IF OWNERSHIP OF AIRCRAFT HAS CHANGED PLEASE FORWARD TO NEW OWNER 407-08-84

Aug. 18, 2008

1 of 26

MODEL AFFECTED: 407

SUBJECT: TAILBOOM A SSEMBLY 407-030-801-201, 407- 030-801-203 AND 407-030-801-205, NEW
INSPECTION REQUIREMENTS.

HELICOPTERS AFFECTED: All model 407 helicopters with one of the subject

tailbooms installed.

COMPLIANCE: PART I Immediately after receipt of this bulletin.

PART II At the next tailboom scheduled inspection and after every 300 flight-hours thereafter.

PART III Within 25 flight- hours or 30 days after accomplishment of Part I. This inspection will affect tailbooms which have accumulated 6900 flight-hours or more, tailbooms with unk nown total flight-hours or tailbooms reaching 6900 flight-hours in service.

PART IV Within 25 flight-hours or 30 days after accomplishment of Part I. This inspection will affect tailbooms which have accumulated 8600 flight-hours or more, tailbooms with unk nown total flight-hours or tailbooms reaching 8600 flight-hours in service.

DESCRIPTION:

Bell Helicopter Textron (BHT) has a ccomplished a thorough analysis of subject

tailbooms which are built wit h chem-milled skins. This an alysis has revealed that areas with high stress concentration could ex ist on the subject tailboom. BHT has not received any field report indicating a crack ed skin in service on subject tailbooms. However, in the interest of safety, BHT has elected to introduce a new inspection schedule to subject tailboom assemblies.ASB 407-08-84 Page 2 of 26

PART I of this Alert Service Bulletin require s identification of t he affected tailboom.

PART II of this bulletin provides the new 30 0-hour recurring inspection details for all subject tailbooms

.

PART III of this bulletin provides additional in spection details for subject tailbooms

which have accumulated 6900 flight-hours or more or with total flight-hours

unknown. Operators have the option to meet the requirement of PART III with a 10X magnifying glass inspection (Option “A”) per formed every 150 flight-hours thereafter or by an Eddy Current inspection method (O ption “B”) performed at every 500-hours

interval.

PART IV of this bulletin provides additional in spection details for subject tailbooms

which have accumulated 8600 flight-hours or more or with total flight-hours

unknown. Operators have the option to meet the requirement of PART IV with a 10X magnifying glass inspection (Option “A”) pe rformed by maintenance personnel every 50 flight-hours thereafter or a visual check (Option “B”) performed daily by the pilot as part of his daily preflight check.

PART V of this bulletin provides the Inst ructions for Continued Airworthiness.

APPROVAL:

The engineering design aspects of this bulletin are TCCA approved.

MANPOWER:

PART I : Approximately 0.25 man-hour is required to accomplish PART I of this

bulletin.

PART II: Approximately 2.5 man-hours are required to accomplish PART II of this

bulletin.

PART III: Approximately 0.50 man-hour is required to accomplish PART III of this bulletin when done under Option “A” (10X magni fying glass inspection method) or 1.0 man-hour when done under Option “B” (E ddy Current inspection method).

PART IV: Approximately 0.25 man-hour is required to accomplish PART IV, Option “A” of this bulletin. There is no impact when Option “B” is selected and done as part of the pilot’s daily preflight check.

NOTE: Man-hours are based on hands-on time , and may vary with personnel and

facilities available.ASB 407-08-84 Page 3 of 26

WARRANTY:

There is no warranty associated with this bulletin.

MATERIAL:

Required Material:

None required.

Consumable Material:

For PART II, PART III and PART IV :

 Aircraft soap (C-318) under MIL-C-87936, as required.

SPECIAL TOOLS:

For Part III, Option “B”(when selected): Eddy Current inspection equipment as described in paragraph 3.0 of Appendix “A”.

WEIGHT AND BALANCE:

Not affected

ELECTRICAL LOAD DATA:

Not affected

REFERENCES:

ASB 407-07-80

BHT-206-SRM-1 BHT-407-MM-1, Rev 24, Maintenance Manual, Chapter 4 BHT-407-MM-5, Rev 18, Maintenance Manual, Chapter 53 Corrosion Control Guide, Chapter 10 BHT-ALL-SPM, Rev. 2, dated 16 February, 2007

PUBLICATIONS AFFECTED:

BHT-407-MM-1, Rev 24, Maintenance Manual, Chapter 4ASB 407-08-84 Page 4 of 26

ACCOMPLISHMENT INSTRUCTIONS:

PART I: Verification of affected tailboom:

1. Upon receipt of this bulletin, verify the helicopter technical records to determine if you have tailboom assembly part num ber 407-030-801-201, 407-030-801-203 or 407-030-801-205 installed on your helicopter. You can also physically confirm the tailboom Part Number by removing the aft driveshaft cover (Ref. Chapter 53 of the maintenance manual) and looki ng at the identification plate located near Boom Station (BS) 129 as shown in Figure 1.

2. If identification as per Step 1 indicates that your tailboom is P/N 407-030-801-107,

407-530-014-101 or 407- 530-014-103, refer to Chapter 4 of your maintenance manual for the inspection schedule appli cable to those tailboom assemblies. Annotate the helicopter technical records to indicate that your tailboom is not affected by this bulletin.

3. If identification as per Step 1 above i ndicates that you have one of the subject tailboom assemblies, verify tailboom histor ical record sheet to determine total flight-hours of your tailboom.

-NOTEIf the total flight-hours of your tailboom is unknow n, it will be

considered to have accumula ted beyond 8600 flight-hours and the requirements described under PART II

, PART III

and PART IV will apply

4. Once the total time in service is known;

a) For all subject tailbooms, regardless of their total time in service, accomplish inspection of your tailboom assembly as defined under PART II of this bulletin at the next scheduled inspection and ev ery 300 flight-hours thereafter.

b) If your tailboom assembly has accumulated 6900 flight-hours or more or if the total time is unknown, incorporate into the inspection schedule of subject

tailbooms defined under PART II , one of the additional in spections as defined

under PART III within the next 25 fli ght-hours in service or 30 days, whichever occurs first and repeat at applicable interval shown.

c) If your tailboom assembly has accumulated more than 8600 flight-hours or if the total flight-hours is unknown, incor porate into the insp ection schedule of subject tailbooms defined under PART II and PART III , one of the additionalASB 407-08-84 Page 5 of 26

inspections as defined under PART IV within 25 flight-hours or 30 days, whichever occurs first and repeat at applicable interval shown.

5. Annotate your technical record s to indicate at which time PART I of this bulletin

was carried out.

PART II Inspection requirements at each 300-hour interval for all subject

tailbooms:

1. Gain access to the areas to be inspected by removing both driveshaft covers and both gearbox fairings halves from your tailboom assembly. Refer to BHT-407-MM5, Chapter 53.

2. Clean the complete tailboom assembly (including the horizontal stabilizer, the two auxiliary finlets and the vertical fin) with aircraft soap (C-318) prepared in

accordance with manufacturer’s recommendati ons to remove all traces of dirt, stains, exhaust residues and oil.

3. (Ref. Figure 2) Examine the complete tailboom assembly following every 300 flighthours of operation for general condition, loos e rivets, cracks or any other type of damage. Pay close attention to Areas “B”, “C”, “D”, “H” and “I” at the left side of the tailboom as indicated in Figure 2.

4. Inspect for loose rivets in region show n in Figure 2, Area “A” and especially at those shown in Details “E”, “F”, “G”, and in Areas “C”, “D”, “H” an d “I”. If a loose rivet or fastener is found, remove it per standard practices and inspect edges of hole for cracks using a 10X magnifying gla ss. If no crack is found, install correct

diameter rivet or fastener (Ref. BHT-206-SRM-1, section 3).

5. If no loose rivets or fasteners are found, use a 10X magnifying glass and examine tailboom skin at edge of bearing hanger supports and around fa steners shown in Figure 2, Details “E”, “F”, “G”, an d Areas “H” and “I”.

6. On left side of tailboom, use a 10X magnifying glass and examine tailboom skin just above edge of mating stabilizer upper a ttachment support as shown in Figure 2, Areas “C” and ”D”.

7. If no crack is found, annotat e the helicopter technical records to indicate that PART

II of this bulletin is complied with and return the tailboom to flight status.

8. Repeat this inspection after every 300 flight-hours thereafter. When your tailboom reaches 6900 and 8600 flight-hours of serv ice, add respectively to this inspection schedule, the applicable recurring insp ection requirements as defined under

PART III and PART IV of this bulletin.ASB 407-08-84 Page 6 of 26

9. If any crack is found in Step 3 through St ep 6 above, replace the tailboom with a serviceable unit prior to next flight and notify Bell Helicopter Product Support Engineering department;

a) If another affected tailboom is installed on the helic opter, determine the total time in service of that tailboom and app ly appropriate inspection program as

defined in this bulletin.

b) If the total flight-hours of your ta ilboom is unknown, accomplish inspection requirements described under PART II

, PART III and PART IV before putting this tailboom in service and repeat at in tervals shown or selected until directed otherwise by BHT.

10. If corrosion is found, refer to Chapter 53 of your maintenance manual for negligible damage limits or contact Product Support Engi neering with details for assistance.

PART III Additional inspection requireme nts for tailbooms with 6900 flighthours or more or with time unknown:

For tailbooms which have reached or exceeded 6900 flight-hours in service or with time unknown, in addition to PART II, incorporate to the inspec tion schedule, one of the following recurring inspections and repeat at the applicable interval shown;

Option “A” (10X Magnifying glass 150-hour recurring inspection):

-NOTEIt is permissible to transfer from one inspection program to the other for maintenance scheduling convenience (ex: Option “A” to Option “B). However, the inspection as

described in the new program must be accomplished prior to next flight. Make an entry in t he helicopter records to show that you have transferred from one inspection option to the other for traceability.

-NOTEThe following inspection must be repeated at a maximum of 150 flight-hours of time in se rvice. However, the aft

driveshaft cover section from the tailboom assembly must be removed to gain proper access to the area to be inspected.ASB 407-08-84 Page 7 of 26

1. Remove the aft driveshaft cover secti on in accordance with Chapter 53 of the

maintenance manual.

2. Use a clean cloth moistened with airc raft soap (C-318) prepared in accordance with manufacturer’s recommendations, as required, to remove any exhaust residues or dirt from areas to inspect, as shown in Figure 2, Areas “H” and “I”.

3. On left side of tailboom, make sure that the tailboom skin is clean and that adequate lighting exists. Use a 10X m agnifying glass and examine tailboom around fasteners shown in Figure 2, Areas “H” and “I”.

4. If a crack is found, replace the tailboom with a serviceable unit prior to next flight and notify Bell Helicopter Produc t Support Engineering department;

a) If another affected tailboom is installed on the helic opter, determine the total

time in service of that tailboom and apply appropriate inspection program as

defined in this bulletin.

b) If the total flight-hours of your ta ilboom is unknown, accomplish inspection requirements described under PART II

, PART III and PART IV before putting this tailboom in service and repeat at in tervals shown or selected until directed otherwise by BHT.

5. If no crack is found, the intent of PART III is complete.

6. Make an entry in the helicopter records to show that PART III, Option “A” of this bulletin is completed.

7. Repeat this inspection after ev ery 150 flight-hour s thereafter.

8. When your tailboom reaches 8600 flig ht-hours, one of the additional recurring inspection requirements defined under PART IV must apply.

Option “B” (Eddy Current 500-hour recurring inspection);

-NOTEIt is permissible to transfer from one inspection program to the other for maintenance scheduling convenience (ex: Option “B” to Option “A). However, the inspection as

described in the new program must be accomplished prior to next flight. Make an entry in t he helicopter records to show that you have transferred from one inspection option to the other for traceability.ASB 407-08-84 Page 8 of 26

-NOTEThe following inspection must be repeated at a maximum of 500 flight-hours of time in se rvice. However, the aft

driveshaft cover section from the tailboom assembly must be removed to gain proper access to the area to be inspected.

1. Remove the aft driveshaft cover secti on in accordance wit h Chapter 53 of the

maintenance manual.

2. Use a clean cloth moistened with airc raft soap (C-318) prepared in accordance with manufacturer’s recommendations, as required, to remove any exhaust residues or dirt from areas to inspect, as shown in Figure 2, Areas “H” and “I”.

3. Refer to Appendix “A” to set and calibra te the Eddy Current inspection equipment.

4. On left side of tailboom, make sure that the tailboom skin is clean and inspect

tailboom skin around fasteners heads in t he shaded areas shown in Figure 2,

Areas “H” and “I”.

5. If a crack is detected, replace the tailb oom with a serviceable unit prior to next flight and notify Bell Helicopter Pr oduct Support Engineering department;

a) If another affected tailboom is installed on the helic opter, determine the total time in service of that tailboom and app ly appropriate inspection program as

defined in this bulletin.

b) If the total flight-hours of your ta ilboom is unknown, accomplish inspection requirements described under PART II

, PART III and PART IV before putting this tailboom in service and repeat at in tervals shown or selected until directed otherwise by BHT.

6. If no crack is found, the intent of PART III is complete.

7. Make an entry in the helicopter records to show that PART III, Option “B” of this bulletin is completed.

8. Repeat this inspection after ev ery 500 flight-hour s thereafter.

9. When your tailboom reaches 8600 flight -hours, one of the additional recurring inspection requirements defined under PART IV must apply.ASB 407-08-84 Page 9 of 26

PART IV Additional inspection require ments for tailbooms with 8600 flighthours or more or with time unknown:

For tailbooms which have reached or exce eded 8600 flight-hours or with total flighthours unknown, in addition to PART II and PART III, incorporate to the inspection schedule, one of the following recurring in spections and repeat at the applicable interval shown;

Option “A” (10X Magnifying glass 50-Hour recurring inspection):

-NOTEIt is permissible to transfer from one inspection program to the other for maintenance scheduling convenience (ex: Option “A” to Option “B). However, the inspection as

described in the new program must be accomplished prior to next flight. Make an entry in t he helicopter records to show that you have transferred from one inspection option to the other for traceability.

1. Use a clean cloth moistened with airc raft soap (C-318) prepared in accordance with manufacturer’s recommendations, as required, to remove any exhaust

residues or dirt from both Areas “C” and “D ” to look at, as shown in Figure 2.

2. On left side of tailboom, make sure that the tailboom skin is clean and that adequate lighting exists. Use a 10X m agnifying glass and examine tailboom around fasteners and just above the edge of upper stabilizer support as shown in Figure 2, Areas “C” and ”D”.

3. If a crack is found, replace the tailboom with a serviceable unit prior to next flight and notify Bell Helicopter Produc t Support Engineering department;

a) If another affected tailboom is installed on the helic opter, determine the total time in service of that tailboom and app ly appropriate inspection program as

defined in this bulletin.

b) If the total flight-time of your ta ilboom is unknown, accomplish inspection requirements described under PART II

, PART III and PART IV before putting this tailboom in service and repeat at in tervals shown or selected until directed otherwise by BHT.

4. If no crack is found, the intent of PART IV is complete.

5. Make an entry in the helic opter records to show that PART IV , Option “A” of this bulletin is completed.ASB 407-08-84 Page 10 of 26

6. Repeat this inspection after ev ery 50 flight-hours thereafter.

Option “B” (Daily recurring check):

-NOTEThis inspection can be performed by the pilot as part of his preflight check with paint/primer still present at the affected

areas. -NOTEIt is permissible to transfer from one inspection program to the other for maintenance scheduling convenience (ex: Option “B” to Option “A). However, the inspection as

described in the new program must be accomplished prior to next flight. Make an entry in t he helicopter records to show that you have transferred from one inspection option to the other for traceability.

1. Use a clean cloth moistened with airc raft soap (C-318) prepared in accordance with manufacturer’s recommendations, as required, to remove any exhaust

residues or dirt from both Areas “C” and “D ” to look at, as shown in Figure 2.

2. On left side of tailboom, make sure that the tailboom skin is clean and that adequate lighting exists. Examine tailboom around fasteners and just above the edge of upper stabilizer support in the shad ed areas shown in Figure 2, Areas “C”

and “D”.

3. If a crack is found, replace the tailboom with a serviceable unit prior to next flight and notify Bell Helicopter Produc t Support Engineering department;

a) If another affected tailboom is installed on the helic opter, determine the total time in service of that tailboom and app ly appropriate inspection program as

defined in this bulletin.

b) If the total flight-time of your ta ilboom is unknown, accomplish inspection requirements described under PART II

, PART III and PART IV before putting this tailboom in service and repeat at in tervals shown or selected until directed otherwise by BHT.

4. If no crack is found, the intent of PART IV is complete.

5. Make an entry in the helic opter records to show that PART IV, Option “B” of this bulletin is completed.ASB 407-08-84 Page 11 of 26

6. Repeat this inspection before firs t flight of each day thereafter.

PART V Instructions for Continued Airworthiness

1. Maintain your tailboom in accordanc e with your 407 Main tenance Manual BHT407-MM-1 and the BHT corrosion c ontrol guide CSSD-PSE-87-001.

2. Inspect your tailboom as per applicabl e requirements and recurring intervals as

described herein.ASB 407-08-84 Page 12 of 26

Figure 1. Location of identificati on plate, tailboom s 407-030-801-201, 407-

030-801-203 or 407-030-801-205.ASB 407-08-84 Page 13 of 26

Figure 2. Inspection schedule for tailbooms 407-030-801- 201, 407-407-030- 801-203 and 407-030-801-205 (Sheet 1 of 6).ASB 407-08-84 Page 14 of 26

Figure 2. Inspection schedule for tailbooms 407-030-801-201, 407-407-030- 801-203 and 407-030-801-205 (Sheet 2).ASB 407-08-84 Page 15 of 26

Figure 2. Inspection schedule for tailbooms 407-030-801-201, 407-407-030- 801-203 and 407-030-801-205 (Sheet 3).ASB 407-08-84 Page 16 of 26

Figure 2. Inspection schedule for ta ilbooms 407-030-801-201, 407-407-030- 801-203 and 407-030-801-205 (Sheet 4).ASB 407-08-84 Page 17 of 26

Figure 2. Inspection schedule for tailbooms 407-030-801-201, 407-407-030- 801-203 and 407-030-801-205 (Sheet 5).ASB 407-08-84 Page 18 of 26

LEGEND:

Figure 2. Inspection schedule for ta ilbooms 407-030-801-201, 407-407-030- 801-203 and 407-030-801-205 (Sheet 6).ASB 407-08-84 Page 19 of 26



## APPENDIX “A”

1.0 Scope

1.1 This procedure is provided to allo w for the detection of 0.050” crack(s) emanating from beneath rivet heads.

1.2 It is intended to provide as close as prac tical detection of cracks oriented in both the vertical and horizontal positions.

2.0 Personnel Requirements

2.1 Personnel performing inspection to this procedure shall be qualified Level II or III per the requirements of NAS 410 or equivalent, OR have successfully completed the BHT CTA NDE Field Mainte nance course. The individual shall be certified as a Level I Special in Eddy Current per employer’s written practice for personnel training and certification.

3.0 Equipment

3.1 NDI Instrument: Hocking Phasec 2 Eddy current flaw detector or equivalent.

3.2 Probe: Absolute pencil probe (50-500 kHz).

3.3 BNC cable.

3.4 BNC cable adapter.

3.5 Teflon tape (C-460).

3.6 Reference standard: Al uminum 3 Notch Crack Standard (P/N 29A029).

4.0 Calibration 4.1 Non-painted surface

4.1.1 Connect cable and probe to the Phasec 2, power ON.

4.1.2 Place a piece of Teflon tape onto t he coil of the probe to decrease wearing of the probe and reduce chance of scratching the material under inspection.

4.1.3 Press the MENU button to enter the setup mode.

4.1.4 Setup instrument per Table 1.

4.1.5 Press the MENU button to exit the setup mode.

4.1.6 Place the pencil probe ont o a good area of the standard away from any edge or crack and press the “ BALANCE (load)” button as shown in Figure

3.

4.1.7 Lift the probe off the standard and adjust the PHASE as necessary so that the trace line (lift-off signal) moves fr om the center of the display to the left and exits the screen horizontally as shown in Figure 4. Re- BALANCE with probe on the standard when complete.

4.1.8 Sweep the probe over the 0.020” reference crack on the standard and verify signal response.

4.1.9 Adjust coarse GAIN values if necessary to increase or decrease crack response amplitude. Figure 5 illustrate s typical response from 0.020” flaw (approximately one grid division).ASB 407-08-84 Page 20 of 26

4.2 Painted surface

4.2.1 Perform steps 4.1.1 through 4.1.5.

4.2.2 BALANCE probe adjacent to the inspecti on area, then place probe on the reference standard (see Figure 7).

4.2.3 The displayed balance point should ap pear to right of the previous balance (null) point (see Figure 6).

4.2.4 Place one layer of notebook paper (~ 3- 4 mils thick) over the calibration standard, and place the pr obe on top of the paper. The balance point

should move left toward the center of the screen. Perform this step adding additional layers of paper until th e balance point returns to center. This step will determine t he approximate paint thic kness in the area of inspection and allow the operator to compensate for any reduction of sensitivity due to the additional lift-off.

4.2.5 With the determined number of notebook paper on top of the standard, Balance the Eddy curr ent probe, and complete steps 4.1.7 through 4.1.9.

NOTE: Any type of paper may be used when compensating for paint thickness. The main consideration is that the paper (or any other material, i.e. plastic shim, tape, et c.) is electrically non-conductive.

5.0 Pre-Inspection

5.1 Ensure surfaces are clean and free of any loose debris, so as not to interfere with the inspection.

6.0 Inspection

6.1 Place the probe in intimate contact with the rivet area(s) to be inspected and Re-adjust the PHASE, if necessary, so that lift-off is horizontal from center null point to left.

6.2 Scan the area of interest circumferentia lly (see Figure 7) while monitoring the display for a sudden increase in signal am plitude from crack- like indications.

7.0 Evaluation

7.1 Repeat calibration and rescan any areas w here there is a vertical crack-like

deflection.

7.2 If indication persists, mark the location on the part.

8.0 Accept/Reject Criteria

8.1 Any repeatable crack-like indi cation detected by the Eddy Current method shall be cause for rejection.ASB 407-08-84 Page 21 of 26

Gain 30.0/ 40.0

X dB 30.0

Y dB 40.0

Phase 201.0

FREQ. 200.0

HIPASS DC

LOPASS Hz 100.0

BAND LOCK OFF

PROBE Absolute

LOAD Uh 120 INPUT GAIN High

RECALL Setup

SAVE Trace

TRACE RECORD ---

OFF ALARM SHAPE Off

TOP ----

BOTTOM ----

LEFT ----

RIGHT ----

START ANGLE ----

END ANGLE ----

INNER ----

OUTER ----

STRETCH 50 ms

ALARM ACTION None

DISPLAY Spot

SWEEP 5.0 s

PERSIST 0.2 s

GRATICULE Grid 1

SPOT X 50%

SPOT Y 50% MODE Normal

PROBE I D

Unknown

POWER DOWN ----

Off

KEY CLICK Off

CONTRAST A/R

VIDEO MODE ---

Normal

LANGUAGE --- English

BAUD 9600

TIME A/R

DAY A/R

MONTH A/R

YEAR A/R

Table 1ASB 407-08-84 Page 22 of 26



## FIGURE 3ASB 407-08-84 Page 23 of 26



## FIGURE 4ASB 407-08-84 Page 24 of 26



## FIGURE 5ASB 407-08-84 Page 25 of 26



## FIGURE 6ASB 407-08-84 Page 26 of 26



## FIGURE 7