ASB No. AS355-05.00.59

Revision 0 2011-08-30 Approved under EASA DOA No. 21J.056. Page 1/9 

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

 Civil version(s): E, F, F1, F2, N, NP

 

ALERT SERVICE BULLETIN

SUBJECT: TIME LIMITS - MAINTENANCE CHECKS - Tail rotor control 

 Checking the locking of the stop screws of the yaw flight controls 

 ATA: 67

 

Revision No. Date of issue 

Revision 0 2011-08-30 

Summary: 

Compliance with this ALERT SERVICE BULLETIN consists in checking the locking of the yaw channel stops. 

Compliance: 

Compliance with this ALERT SERVICE BULLETIN is mandatory. 

For the attention of 
 

ASB No. AS355-05.00.59

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1. PLANNING INFORMATION 

1.A. EFFECTIVITY 

1.A.1. Helicopters/installed equipment 

AS355 helicopter versions E, F, F1, F2, N, NP equipped with the Automatic Pilot (AP). 

or, 

AS355 helicopter versions N and NP not equipped with the AP, embodying modification 071908. 

NOTE

Refer to the aircraft individual inspection record (MOD 

record) and the aircraft log book to identify the actual 

configuration of the helicopter. 

1.A.2. Non-installed equipment 

Not applicable. 

1.B. ASSOCIATED REQUIREMENTS 

Not applicable. 

1.C. REASON 

During take-off with sling load on an AS350 B3 helicopter, the pilot noticed that he reached one of the yaw 

stops before its usual position. The mechanic found that the locknut of the yaw stop was loose and that the 

yaw stop was out of adjustment. 

The yaw stop screws of the flight controls of AS355 helicopters are identical to those of AS350 helicopters. 

The loss of locking can lead to the loss of adjustment of the stop concerned and cause a limited yaw 

authority. 

Consequently, pending a modification, EUROCOPTER renders the periodic check of the locking of the yaw 

channel stop screws, mandatory. 

Revision 0 of this ALERT SERVICE BULLETIN will form the subject of an EASA Airworthiness Directive. 

1.D. DESCRIPTION 

Compliance with this ALERT SERVICE BULLETIN consists in: 

- checking the locking of the stop screws, 

- if necessary, adjusting the stops, 

- marking a line of paint on the screw/nut assembly, 

- checking periodically the alignment of the paint line on the screw/nut assembly. 
 

ASB No. AS355-05.00.59

Revision 0 2011-08-30 Approved under EASA DOA No. 21J.056. Page 3/9 

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1.E. COMPLIANCE 

1.E.1. Compliance at the works 

Helicopters/installed equipment: 

Before delivery, comply with paragraph 3.B.2. of this ALERT SERVICE BULLETIN, issued on the date 

indicated at the bottom of the page. 

 

 Non-installed equipment: 

Not applicable. 

1.E.2. Compliance in service 

The operations on the helicopter are to be performed by the operator. 

Helicopters/installed equipment: 

Comply with paragraph 3.B.2. within 110 flying hours following receipt of this ALERT SERVICE BULLETIN, 

issued on the date indicated at the bottom of the page. 

then, 

 

comply with paragraph 3.B.3. every 110 flying hours. 

 Non-installed equipment: 

Not applicable. 

1.F. APPROVAL 

 

 Approval of modifications:

 Not applicable.

 Approval of this document: 

The technical information contained in this ALERT SERVICE BULLETIN Revision 0 was approved 

on August 26, 2011 under the authority of EASA Design Organization Approval No. 21J.056 for helicopters 

of civil versions subject to an Airworthiness Certificate. 

The technical information contained in this ALERT SERVICE BULLETIN Revision 0 was approved 

on August 26, 2011 under the prerogatives of the recognition of design capability FRA21J-002-DGA for 

French Government helicopters. 
 

ASB No. AS355-05.00.59

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1.G. MANPOWER 

EUROCOPTER recommends that compliance with this ALERT SERVICE BULLETIN is ensured by 

personnel with the following qualifications: 

Qualification: - 1 Mechanical Engineering Technician 

 

 The time for the operations is given for information purposes, for a standard configuration. 

Time for the operations: - approximately 10 minutes for compliance with paragraph 3.B.2. 

 - approximately 10 minutes for compliance with paragraph 3.B.3. 

1.H. WEIGHT AND BALANCE 

Weight and moment negligible. 

1.I. EFFECT ON ELECTRICAL LOADS 

Not applicable. 

1.J. SOFTWARE MODIFICATION EMBODIMENT RECORD 

Not applicable. 

1.K. REFERENCES 

The following documents are required for compliance with this ALERT SERVICE BULLETIN. 

MET: 67.10.00.301: MAIN ROTOR CONTROLS: General instructions 

MET: 67.20.00.502: TAIL ROTOR CONTROLS - Rigging: Versions E,F,F1,F2 "WITH AUTOMATIC PILOT", 

Version N "WITH AND WITHOUT AP" 

MTC: 20.04.01.102: CLEANING - Description and use of standard cleaning products for individual parts 

and on aircraft 

 
 

ASB No. AS355-05.00.59

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1.L. DOCUMENTS AFFECTED 

 EUROCOPTER will update the Maintenance Program (PRE) in accordance with this ALERT SERVICE BULLETIN. 

The document concerned will be updated as part of a future revision. 

1.M. INTERCHANGEABILITY OR MIXABILITY OF PARTS 

Not applicable.
 

ASB No. AS355-05.00.59

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2. MATERIAL INFORMATION 

2.A. MATERIAL: PRICE - AVAILABILITY - PROCUREMENT 

Not applicable. 

2.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT 

Not applicable. 

2.C. MATERIAL REQUIRED FOR EACH HELICOPTER/COMPONENT 

 Products to be ordered separately: 

Refer to the Work Cards specified in this ALERT SERVICE BULLETIN and the list below: 

Key Word Qty Product P/N CM Item 

No. 

 

red paint A/R Off the shelf / 1 

 

 The products can be ordered separately from the INTERTURBINE AVIATION LOGISTICS company. 

 Website: http://www.interturbine.com

 Telephone: +49.41.91.809.300 

AOG: +49.41.91.809.444 

2.D. MATERIAL TO BE RETURNED 

Not applicable. 
 

ASB No. AS355-05.00.59

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3. ACCOMPLISHMENT INSTRUCTIONS 

3.A. GENERAL 

Read and comply with the general instructions concerning flight controls as per MET Work Card 

67.10.00.301. 

3.B. OPERATIONAL PROCEDURE 

3.B.1. Preliminary steps

- Open the baggage compartment. 

- Remove all panels or trimmings as required for access to the different work areas. 

3.B.2. Initial check of the locking of the stop screws (Figure 1) 

- Check using a screwdriver for recessed head screws that the screws (a) (Figure 1) of the yaw stops do not 

turn: 

. If a stop screw (a) turns: 

- adjust the stops as per MET Work Card 67.20.00.502, 

- mark a line of red paint (1) on the screw/nut assembly (Section B-B, Figure 1). 

. If no stop screw (a) turns: 

- mark a line of red paint (1) on the screw/nut assembly (Section B-B, Figure 1). 

3.B.3. Periodic check of the locking of the stop screws (Figure 1) 

- Check the locking of the stop screw by making sure that the red paint lines on the screw (a) and on the nut 

(b) are aligned: 

 . if the red paint lines are aligned: 

 - leave as is. 

. if the red paint lines are not aligned: 

- inform the Technical Support Department of EUROCOPTER: 

Fax: + 33 (0)4.42.85.99.66. 

E-mail: Hydraulics.Technical-Support@eurocopter.com

- clean the marks of red paint on the screw (a) and the nut (b). 

- adjust the stops as per MET Work Card 67.20.00.502, 

- mark a line of red paint (1) on the screw/nut assembly (Section B-B, Figure 1) 

3.B.4. Final steps

- Install all panels and trimmings removed during preliminary steps (paragraph 3.B.1.). 

- Close the baggage compartment. 
 

ASB No. AS355-05.00.59

Revision 0 2011-08-30 Approved under EASA DOA No. 21J.056. Page 8/9 

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3.C. IDENTIFICATION 

 Identification of this document: 

Record initial compliance with this document and its revision number in the helicopter documents. 

 

3.D. OPERATING AND MAINTENANCE INSTRUCTIONS 

Not applicable. 
 

ASB No. AS355-05.00.59

Revision 0 2011-08-30 Approved under EASA DOA No. 21J.056. Page 9/9 

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Figure 1 

A

B B

B

B a 

a SECTION 

B - B 

a 

1 

b