### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 1/11

2007.04.11 EUROCOPTER

DIRECTION TECHNIQUE SUPPORT

13725 MARIGNANE C EDEX F RANCE



# EMERGENCY 

# ALERT SERVICE BULLETIN

ECUREUIL NUMBER VERSIONS

Civil: B,BA,BB,B1,B2,B3,D 

# 350 53.00.37 Military: L1 

# 550 53.00.11 Military: A2, C2, C3, U2



# 355 53.00.23 Civil: E, F, F1, F2, N

AF, AN, MN, SN, UF, 

# 555 53.00.11 Military: UN



### SUBJECT: Fuselage

Check of the conformity of the center cross member at X 2325 under

the cabin floor

REVISION No. DATE OF APPROVAL DATE OF ISSUE

Revision 0 On: April 11, 2007 2007.04.11

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 2/11

2007.04.11 

### 1. PLANNING INFORMATION

1.A. EFFECTIVITY

1.A.1. Helicopters / Installed equipment

Center cross member at X 2325 under the cabin floor of helicopters equipped with a collective-to-yaw control coupling (see Figure 1 item 6), with or without an Automatic Flight Control System.



### NOTE

Helicopters delivered after January 1, 2007 are not concerned by the instructions of this ALERT

SERVICE BULLETIN.

1.A.2. Non-installed equipment

Not applicable.



### 1.B. ASSOCIATED REQUIREMENTS

Not applicable.



### 1.C. REASON

To make sure that the structure under the cabin fl oor is in accordance with standard, i.e. that the following components are present on helicopters fitted wi th a collective-to-yaw control coupling (6) with or without an Automatic Flight Control System (see Figure 1): - the doublers (2) and (3) at X 2325, - the cross member (1) at X 2165.

This ALERT SERVICE BULLETIN will form the subject of an EASA Airwor thiness Directive.



### 1.D. DESCRIPTION

EUROCOPTER has recently received a report of a cr ack that was discovered in the area of the center cross member at X 2325, at the attachment point of the sheath stop of the yaw channel ball-type control on an AS355 N helicopter fitted with the collective-to-yaw control coupling. Initial investigation revealed a rare non-conformity on this helicopter, i.e. it was not equipped with the

structure doublers which are combined with the coll ective-to-yaw coupling installation. These same doublers are installed if the helicopter is fitt ed with an Automatic Flight Control System. The investigation also revealed in this case, incorrect rigging of the yaw channel ball-type control,

which caused excess load on the cross member at X 2325.

Excess load on the cross member can cause it to crac k. This crack can reduce the yaw control travel. In the event of significant reducti on, the yaw control of the helicopter may become difficult in certain flight configurations. EUROCOPTER emphasizes that correct rigging of t he yaw control channel is important and issued TELEX INFORMATION No. 00000372 on this subject, on February 28, 2007.

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 3/11

2007.04.11 

### 1.E. COMPLIANCE

EUROCOPTER renders compliance with the measur es defined in this ALERT SERVICE BULLETIN mandatory.

1.E.1. Compliance at the works

1.E.1.a. On helicopters: Not applicable.

1.E.1.b. On non-installed equipment: Not applicable.

1.E.2. Compliance in operation: By the operator:

1.E.2.a. On helicopters / installed equipment:

1) Comply with paragraph 2.B. within 10 flying hour s or within one month (the first limit reached is applicable) from receipt of this ALERT SERVICE BULLETIN, issued on the date indicated at the foot of the page.

2) Following compliance with paragraph 2.B.:

For helicopters in the configurat ion defined in paragraph 2.B.2.b.

Comply with paragraph 2.B.2.b. at intervals not exceeding 55 flying hours, pending compliance with paragraph 4 (return to conformity of the structure unde r the cabin floor).

Ensure compliance with paragraph 4. within 12 months following receipt of this ALERT SERVICE BULLETIN, issued on the date i ndicated at the foot of the page.

1.E.2.b. On non-installed equipment:

Not applicable.



### 1.F. APPROVAL

Approval is limited to civil version helicopte rs subject to an Airworthiness Certificate.

The technical information contained in th is ALERT SERVICE BULLETIN was approved on April 11, 2007 under the authority of EASA Design Organisation Approval No. 21J.056.



### 1.G. MANPOWER

Qualification: Mechanic or aircraft structure specialist.

Time for the operations: Approximately 15 minutes to ensure compliance with paragraph 2.B.1. Approximately 30 minutes to ensure compliance with paragraph 2.B.2. Approximately 15 hours to ensure compliance with paragraph 4.

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 4/11

2007.04.11 

### 1.H. WEIGHT AND BALANCE

Not applicable.



### 1.I. EFFECT ON ELECTRICAL LOADS

Not applicable.



### 1.J. SOFTWARE MODIFICATION EMBODIMENT STATE

Not applicable.



### 1.K. REFERENCES

The following documents are necessary for compliance with paragraph 2.B.:

- Maintenance Manual (MET), Work Cards: 53.00.00.405 and 67.20.00.502.

- Standard Practices Manual (MTC ), Work Card: 20.02.09.601.

The following documents are necessary for compliance with APPENDIX paragraph 4:

- Maintenance Manual (MET), Work Card s: 53.00.00.405, 67.20.00.502 and 67.20.00.406.

- Standard Practices Manual (MTC), Wo rk Cards: 20.02.04.401, 20.04.05.402 and

20.04.05.403.



### 1.L. OTHER DOCUMENTS CONCERNED

Not applicable.



### 1.M. TOOLING CONCERNED

Not applicable.



### 1.N. INTERCHANGEABILITY AND MIXABILITY OF PARTS

Not applicable.

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 5/11

2007.04.11 

### 2. ACCOMPLISHMENT INSTRUCTIONS

2.A. GENERAL

Not applicable.



### 2.B. OPERATIONAL PROCEDURE

2.B.1. Preliminary steps

Remove the bottom structure aft lower fairing as per MET Work Card 53.00.00.405.

2.B.2. Visual check for presence of the cr oss member at X 2165 and the doublers at X 2325 and

at Y 269 in the bottom structure

As per Figure 1: - Visually check that the cross member (1) and the doublers (2) and (3) are present.

Interpretation of the results:

a) If the cross member (1) and the doublers (2) and (3) are present:

- Leave as is.

- Install the bottom structure aft lower fair ing in compliance with paragraph 2.B.3. - Resume flights.

b) If the cross member (1) and / or the doublers (2) and (3) are missing:

- Make sure that there is no crack in the c enter cross member (4), in the area around the

attachment point of the tail rotor directional ball-type control (5). If in doubt, carry out a dye penetrant crack detection inspection as per MTC Work Card 20.02.09.601.

1) If there is no crack: - Check the tail rotor control rigging as per MET Work Card 67.20.00.502 during the initial

visual check.

- Leave as is.

- Install the bottom structure aft lower fair ing in compliance with paragraph 2.B.3. - Resume flights. - Comply with paragraph 1.E.2.a.2 pending co mpliance with APPENDIX paragraph 4 which

describes the procedure for retu rning the bottom structure to c onformity (installing the cross member (1) and the doublers (2) and (3)).

2) If there is a crack: - Suspend flights. - Contact the EUROCOPTER Technical Support Department STVA for replacing the

cracked cross member and returni ng the structure to conformity, by

. Tel: +33 (0)4.42.85.97.03 . Fax: +33 (0)4.42.85.99.66.

2.B.3. Final steps

Install the bottom structure aft lower fair ing as per MET Work Card 53.00.00.405.

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 6/11

2007.04.11 

### 2.C. IDENTIFICATION

Record compliance with this ALERT SERV ICE BULLETIN in the aircraft documents.



### 2.D. OPERATING AND MAINTENANCE INSTRUCTIONS

Not applicable.

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 7/11

2007.04.11 Figure 1 1 2

3 X 2325

Y 269 

# A

AV

FWD 5

4 X 2165

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 8/11

2007.04.11 Figure 2

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 9/11

2007.04.11 Figure 3

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 10/11

2007.04.11 

### 3. MATERIAL INFORMATION

3.A. MATERIAL: COST – AVAILABILITY

Not applicable.



### 3.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT

Not applicable.



### 3.C. MATERIAL REQUIRED FOR EACH HELICOPTER / ENGINE / COMPONENT

3.C.1. Component(s) to be ordered for one helicopter to ensure co mpliance with APPENDIX paragraph 4.

Material

Part Number Qty Item Key Word Former Part Number Instructions

350A21-1358-24 1 1 Cross member

350A21-1014-21 1 2 Doubler

350A21-1014-20 1 3 Doubler

21215DC3210J 44 4 Rivet



### 3.D. PROCUREMENT CONDITIONS

Order the required quantity (unless otherwise specified)

from

EUROCOPTER Etablissement de Marignane

Sales and Customer Relations Directorate

ECR

13725 MARIGNANE CEDEX

FRANCE


### NOTE 1

For ALERT SERVICE BULLETINS, order by:

Telex: HELICOP 410 969F Fax: +33 (0)4 42 85 99 96



### NOTE 2

On the purchase order, please specify the mode of transport, the destination and the serial numbers of the helicopters

to be modified.

### T.F.S. No. 00000360

Approved under EASA DOA No. 21J.056 Page 11/11

2007.04.11 

### 4. APPENDIX

4.1. Preparation of the helicopter

- It is advisable to jack up the helicopter in order to ensure a maximum ground clearance to carry out

the work under the cabin floor. - Remove or fold the rear seats against the bulkhead. - Remove the mats or carpeting (if any) from the cabin floor.

- Remove the bottom structure lower fair ings, as per MET Work Card 53.00.00.405. - Remove the ball-type control between the control le ver of the collective-to -yaw control coupling and

the aft fuselage-to-tail boom junction frame, as per MET Work Card 67.20.00.406.

4.2. Procedure for installing the cros s member (1) and the doublers (2) and (3)

As shown on Figures 2 and 3

- Clean the installation areas for the cross member (1) and the doublers (2) and (3) with a cloth

moistened with cleaning product (White Spirit).



### NOTE

The rivet hole pitches and positioning distances are

defined in MTC Work Card 20.02.04.401.

- Mark out the location of the 6 rivets (4) on the doublers (2), (3) and on the cross member (1). - Position and secure the doubler (2) at Y 299 on the cross member (a), at X 2325, and so that it bears

against the cabin floor (b), . drill 6 x 2.5 mm diameter pilot holes and temporarily secure the doubler (2) to the cross member (a). - Position and secure the doubler (3) at Y 239 on the cross member (a), at X 2325, and so that it bears

against the cabin floor (b), . drill 6 x 2.5 mm diameter pilot holes and temporarily secure the doubler (3) to the cross member (a). - Position and secure the cross member (1) at X 2165, and so that it bears against the cabin floor (a) and against the doublers (2) and (3):

. check the trueness of the doublers (2) and (3), . drill 3 x 2.5 mm diameter pilot holes and temporarily secure the cross member (1) to the longitudinal

beam (c) at Y 398.5, . drill 3 x 2,5 mm diameter pilot holes and temporarily secure the cross member (1) to the doubler (d)

at Y 162, . drill 3 x 2.5 mm diameter pilot holes in each doubler (2) and (3). - Drill the 2.5 mm diameter pilot holes between the cr oss beam (1) and the cabin floor (b), and between

the doublers (2), (3) and the cabin floor (b).

- Drill out all the 2.5 mm diameter holes to a diameter of 3.3 mm. - Secure the cross member (1) and the doublers (2) an d (3) with rivets (4), as per MTC Work Card

20.02.04.401, . cut the rivets (4) to length, as required, accordi ng to the thickness of the parts to be assembled. - On the doublers (2) and (3), drill out the two 5.1 mm diameter holes for the installation of the swivel

bearing retainer. - Touch up with P05 epoxy primer, as per MTC Work Card 20.04.05.402. - Touch up the finish paint on and under the cabi n floor, as per MTC Work Card 20.04.05.403. - Install the ball-type control between the control leve r of the collective-to-yaw control coupling and the

aft fuselage-to-tail boom junction frame, as per MET Work Card 67.20.00.406. - Remove the jacks under the helic opter if they were installed. - Adjust the tail rotor control as per MET Work Card 67.20.00.502.

- Install the bottom structure lower fairin gs as per MET Work Card 53.00.00.405. - Return the helicopter to flight configuration.