T.F.S. No. 00000360 

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

2007.04.11

EUROCOPTER 

DIRECTION TECHNIQUE SUPPORT

13725 MARIGNANE CEDEX FRANCE

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 floor is in accordance with standard, i.e. that the 

following components are present on helicopters fitted with 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 Airworthiness Directive. 

1.D. DESCRIPTION 

EUROCOPTER has recently received a report of a crack 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 collective-to-yaw coupling installation. These same 

doublers are installed if the helicopter is fitted 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 crack. This crack can reduce the yaw control travel. 

In the event of significant reduction, the yaw control of the helicopter may become difficult in certain 

flight configurations. 

EUROCOPTER emphasizes that correct rigging of the 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 measures 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 hours 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 configuration 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 under the cabin floor). 

Ensure compliance with paragraph 4. within 12 months following receipt of this ALERT 

SERVICE BULLETIN, issued on the date indicated 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 helicopters subject to an Airworthiness Certificate. 

The technical information contained in this 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 Cards: 53.00.00.405, 67.20.00.502 and 67.20.00.406. 

- Standard Practices Manual (MTC), Work 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 cross 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 fairing 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 center 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 fairing in compliance with paragraph 2.B.3. 

- Resume flights. 

- Comply with paragraph 1.E.2.a.2 pending compliance with APPENDIX paragraph 4 which 

describes the procedure for returning the bottom structure to conformity (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 returning 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 fairing 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 SERVICE 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 compliance 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 fairings, as per MET Work Card 53.00.00.405. 

- Remove the ball-type control between the control lever 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 cross 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 cross 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) and (3) with rivets (4), as per MTC Work Card 

20.02.04.401, 

. cut the rivets (4) to length, as required, according 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 cabin floor, as per MTC Work Card 20.04.05.403. 

- Install the ball-type control between the control lever 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 helicopter if they were installed. 

- Adjust the tail rotor control as per MET Work Card 67.20.00.502. 

- Install the bottom structure lower fairings as per MET Work Card 53.00.00.405. 

- Return the helicopter to flight configuration.