ALERT SERVICE BULLETIN AS365 

Approved under EASA DOA No. 21J.056. 01.00.59 Page 1/9

 2007.06.21

 

This document is available on the internet: www.eurocopter.com/techpub 

 EUROCOPTER

DIRECTION TECHNIQUE SUPPORT

13725 MARIGNANE CEDEX FRANCE CIVIL VERSION(S): N1,N2,N3 

 MILITARY VERSION(S): F,Fi,K 

 ALERT SERVICE BULLETIN 

No. 01.00.59 

SUBJECT: LIMITATIONS

Tail Rotor Blade Pitch-Control Shafts Part No. 365A33.6161.20 or 21 

(Pre-MOD 0765B41 Aluminum Control Shafts)

ATA: 65 

REVISION No. DATE OF APPROVAL DATE OF ISSUE 

 

Revision 0 On: June 21, 2007 2007.06.21 

 

 
 ALERT SERVICE BULLETIN AS365 

Approved under EASA DOA No. 21J.056. 01.00.59 Page 2/9

 2007.06.21

 

1. PLANNING INFORMATION 

1.A. EFFECTIVITY 

1.A.1. Helicopters/Installed Equipment 

Tail gearboxes (TGBs) equipped with a tail rotor blade pitch-control shaft Part No. 365A33-6161-20 or 21. 

(See the NOTE below). 

1.A.2. Non-Installed Equipment 

TGBs equipped with a tail rotor blade pitch-control shaft Part No. 365A33-6161-20 or 21. (See the NOTE 

below). 

NOTE

The control shaft, whatever its part number, is a part subject to 

in-service monitoring. Therefore, its part number and its serial 

number are recorded in the TGB Log Card (FM). 

The TGBs with MOD 0765B41 recorded in their Log Card, and 

TGBs Part No. 365A33.6005.05, .06, .07, and .08 are not 

concerned by this ALERT SERVICE BULLETIN as they are 

equipped with a steel control shaft Part No. 365A33.6214.20. 

1.B. ASSOCIATED REQUIREMENTS 

Not applicable. 

1.C. REASON 

Declaring pitch-control shafts Part No. 365A33-6161-20 and 21, unfit for flight from December 31, 2007. 

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

1.D. DESCRIPTION 

An instance of in-flight loss of tail rotor control on an AS365 N2 helicopter has recently been reported to 

EUROCOPTER. This event led the pilot to execute a run-on landing (in compliance with the Flight Manual 

emergency procedures), which occurred with no further problems. 

On the ground, the tail rotor blade pitch-control shaft was then found broken (aluminum control shaft Part 

No. 365A33.6161.21). 

This failure occurred in the main section of the sliding area, between the control shaft and the output pinion 

(control shaft area protected by a hard tungsten carbide deposit). 

The failed area was damaged by peening and, therefore, it was not possible to identify the start of the crack, 

which had developed under fatigue loading. 
 ALERT SERVICE BULLETIN AS365 

Approved under EASA DOA No. 21J.056. 01.00.59 Page 3/9

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Further analyses associated with in-flight load measurement provided no explanations on how the crack 

started, assuming normal operating conditions for the tail rotor head. The most probable assumption is that 

accidental damage to the shaft (shock impact or distortion) caused a crack in the hard tungsten carbide 

deposit. As, generally, such damage is not detectable on this type of material, a non-detected crack in the 

deposit may develop through the control shaft in an area that is not accessible from outside. 

To prevent the failure of the pitch-control shaft, which would cause the loss of tail rotor control, 

EUROCOPTER renders the instructions specified in this ALERT SERVICE BULLETIN mandatory. 

1.E. COMPLIANCE 

EUROCOPTER renders compliance with 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: Upon receipt of this ALERT SERVICE BULLETIN 

- Prohibit the delivery of TGBs equipped with a pitch-control shaft 

Part No. 365A33-6161-20 or 21. 

- Prohibit the delivery of pitch-control shafts Part No. 365A33-6161-20 

and 21. 

1.E.2. Compliance in Operation: By the Operator: 

1.E.2.a. On Helicopters/Installed Equipment 

Comply with paragraph 2.B. of this ALERT SERVICE BULLETIN (issued on the date specified in the page 

footer) before December 31, 2007. 

CAUTION 

FROM DECEMBER 31, 2007 ONWARD, TAIL ROTOR BLADE 

PITCH-CONTROL SHAFTS PART No. 365A33-6161-20 

AND 21 WILL BE UNFIT FOR FLIGHT. 

1.E.2.b. On Non-Installed Equipment: 

1) For TGBs equipped with a pitch-control shaft Part No. 365A33-6161-20 or 21, ensure compliance with 

paragraph 2.B. of this ALERT SERVICE BULLETIN before installation on helicopter or at the latest 

before December 31, 2007. 

2) Discard pitch-control shafts Part No. 365A33-6161-20 and 21 before December 31, 2007. Refer to 

paragraph 3.E. for returning the equipment to EUROCOPTER. 
 ALERT SERVICE BULLETIN AS365 

Approved under EASA DOA No. 21J.056. 01.00.59 Page 4/9

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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 June 21, 2007 under the authority of EASA Design Organisation Approval No. 21J.056. 

1.G. MANPOWER 

Qualification: 1 mechanic. 

Time for the operations: Approximately 12 hours. 

1.H. WEIGHT AND BALANCE 

1.H.1. Weight: +0.538 kg. 

1.H.2. Moment: +5.61 m.kg. 

1.I. EFFECT ON ELECTRICAL LOADS 

Not applicable. 

1.J. SOFTWARE MODIFICATION EMBODIMENT STATE 

Not applicable. 

1.K. REFERENCES 

Maintenance Manual (MET) Work Cards: 12.00.00.308, 24.00.00.300, 29.00.00.301, 

64.21.02.402, 67.30.21.401. 

Repair Manual (MRR) Work Cards: 65.21.00.701, 65.21.00.702. 

1.L. OTHER DOCUMENTS CONCERNED 

Maintenance Program (PRE). 

1.M. TOOLING CONCERNED 

Not applicable. 

1.N. INTERCHANGEABILITY OR MIXABILITY OF PARTS 

Not applicable. 
 ALERT SERVICE BULLETIN AS365 

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2. ACCOMPLISHMENT INSTRUCTIONS 

2.A. GENERAL 

Before performing any work, refer to the general safety instructions related to electrical and hydraulic power 

systems given in MET Work Cards 24.00.00.300 and 29.00.00.301. 

2.B. OPERATIONAL PROCEDURE 

2.B.1. Preliminary Steps 

- Drain the TGB as per MET Work Card 12.00.00.308. 

- Remove the Tail Rotor Head (TRH) as per MET Work Card 64.21.02.402. 

- Remove the tail servocontrol as per MET Work Card 67.30.21.401. 

2.B.2. Procedure 

Refer to Figure 1. 

2.B.2.a. Removing the Pitch-Control Rod/Shaft Assembly 

- Remove the pitch-control rod (2)/shaft (a) assembly as per MRR Work Card 65.21.00.701. 

- Remove pitch-control shaft (a) from rod (2) as per MRR Work Card 65.21.00.702. 

NOTE

Before reinstallation on pitch-control shaft (1), check for axial 

play in the bearing on rod (2) (preloaded bearing). 

2.B.2.b. Installing the Pitch-Control Rod/Shaft Assembly 

- Assemble pitch-control shaft (1) and rod (2) as per MRR Work Card 65.21.00.702. 

- Install pitch-control shaft (1) and rod (2) on the TGB as per MRR Work Card 65.21.00.701. 

2.B.3. Final Steps 

- Install the tail servocontrol as per MET Work Card 67.30.21.401. 

- Install the TRH as per MET Work Card 64.21.02.402. 

- Fill up the TGB with oil as per MET Work Card 12.00.00.308. 

- Return the aircraft to flight configuration. 
 ALERT SERVICE BULLETIN AS365 

Approved under EASA DOA No. 21J.056. 01.00.59 Page 6/9

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2.C. IDENTIFICATION 

On the TGB Log Card (FM), record: 

- Compliance with this ALERT SERVICE BULLETIN. 

- Embodiment of Modification 0765B41 and replace the part number and serial number of the removed shaft 

by those of the newly installed shaft. 

2.D. OPERATING AND MAINTENANCE INSTRUCTIONS 

Not applicable. 
 ALERT SERVICE BULLETIN AS365 

Approved under EASA DOA No. 21J.056. 01.00.59 Page 7/9

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Figure 1 
 ALERT SERVICE BULLETIN AS365 

Approved under EASA DOA No. 21J.056. 01.00.59 Page 8/9

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3. MATERIAL INFORMATION 

3.A. MATERIAL: COST - AVAILABILITY 

3.A.1. Cost 

For any information concerning kits and/or components, contact the Sales and Customer Relations 

Department of the EUROCOPTER Network. 

3.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT 

Not applicable. 

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

3.C.1. Kit(s) or Component(s) to be Ordered for One Helicopter or One Assembly 

Material Part Number Qty Item Key Word Former Part Number Instructions 

 

365A33-6214-20 1 1 Control shaft 365A33-6161-21 Discard 

 

The components necessary for replacing the pitch-control shaft are to be ordered according to the needs 

and as required for compliance with MRR Work Cards 65.21.00.701 and 65.21.00.702, or according to the 

kit for embodiment of MOD 0765B41, which is defined in Service Bulletin No. 65.00.14 

(Kit No. 365A07-65B4-171). 

3.C.2. Component(s) to be Ordered Separately 

The materials identified by an asterisk "*" or required for compliance with the tasks and/or work cards listed in 

paragraph 1.K., can be ordered from the INTERTURBINE company, 

Website: http://www.itlogistics.de

Phone: +49.41.91.809.300 

AOG: +49.41.91.809.444 
 ALERT SERVICE BULLETIN AS365 

Approved under EASA DOA No. 21J.056. 01.00.59 Page 9/9

 2007.06.21

 

3.D. PROCUREMENT CONDITIONS 

Order the required quantity (unless otherwise specified) 

from 

EUROCOPTER 

Etablissement de Marignane 

Direction Ventes et Relations Client 

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, always specify the mode of transport, the 

destination, and the serial numbers of the aircraft to be modified. 

3.E. MATERIAL TO BE RETURNED 

Return the equipment to EUROCOPTER Marignane along with a warranty claim, in accordance with the 

procedure described in Service Letter No. 1627.00.03. 

4. APPENDIX 

Not applicable. 

 ALERT SERVICE BULLETIN AS365 

Approved under EASA DOA No. 21J.056. 01.00.59 Page 9/9

 2007.06.21

 

3.D. PROCUREMENT CONDITIONS 

Order the required quantity (unless otherwise specified) 

from 

EUROCOPTER 

Etablissement de Marignane 

Direction Ventes et Relations Client 

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, always specify the mode of transport, the 

destination, and the serial numbers of the aircraft to be modified. 

3.E. MATERIAL TO BE RETURNED 

Return the equipment to EUROCOPTER Marignane along with a warranty claim, in accordance with the 

procedure described in Service Letter No. 1627.00.03. 

4. APPENDIX 

Not applicable.