ALERT SERVICE BULLETIN AS332 

Approved under EASA DOA No. 21J.056. 62.00.66 Page 1/9

 2006.09.13

 EUROCOPTER

DIRECTION TECHNIQUE SUPPORT

13725 MARIGNANE CEDEX FRANCE CIVIL VERSION(S): L2 

 

 ALERT SERVICE BULLETIN 

No. 62.00.66 

SUBJECT: MAIN ROTOR

Swashplate Bearing Attachment Screws

REVISION No. DATE OF APPROVAL DATE OF ISSUE 

 

Revision 0 On: September 7, 2006 2006.09.13 

 

 
 ALERT SERVICE BULLETIN AS332 

Approved under EASA DOA No. 21J.056. 62.00.66 Page 2/9

 2006.09.13

1. PLANNING INFORMATION 

1.A. EFFECTIVITY 

1.A.1. Helicopter / Installed equipment 

On Main Rotor Mast assemblies pre MOD 0743714 (All Part Numbers). 

NOTE

Main Rotor Mast assemblies post MOD 0743714 are not 

concerned by this ALERT SERVICE BULLETIN (see log 

card (FM) of the Rotor Mast assembly). 

1.A.2. Non-installed equipment 

Not applicable. 

1.B. ASSOCIATED REQUIREMENTS 

Not applicable. 

1.C. PURPOSE 

Introduce an integrity periodic check of the swashplate bearing attachment screws. 

The purpose of this ALERT SERVICE BULLETIN, which supersedes Revision 2 of ALERT TELEX 

No. 62.00.66, issued on October 26, 2005, with no change to the technical content, is to: 

- Inform the users that the Main Rotor Mast Assemblies post MOD 0743714 are not concerned by this 

ALERT SERVICE BULLETIN. 

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

1.D. DESCRIPTION 

With Revision 0 of ALERT TELEX No. 62.00.66 issued on April 29, 2005, EUROCOPTER informed you that 

during a daily maintenance inspection, two broken screw heads lockwired together were discovered in the 

attachment zone of an MRH servo-control. Two other pairs of broken screw heads were also discovered on 

the transmission deck. 

Investigations revealed that these screw heads were those used for swashplate bearing attachment and that 

8 out of the 21 screws were broken. 

The purpose of Revision 1 of ALERT TELEX No. 62.00.66 issued on July 13, 2005 by EUROCOPTER was 

to inform you that, since the issue of Revision 0 of ALERT TELEX No. 62.00.66, no other case had been 

reported and that the concerned swashplate assembly had been returned and investigated at 

EUROCOPTER. The investigations demonstrated that the ruptures detected on all the screws were 

progressive failures due to fatigue. 
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A loss of tightening torque on a number of remaining screws, and extensive fretting in the non-rotating 

swashplate/bearings/rotating swashplate stacked assembly were also noted. 

The initial analysis results revealed that the loss of tightening torque of the swashplate bearing attachment 

screws was the probable cause of their progressive fatigue rupture. 

EUROCOPTER has continued these analyses and has studied a modification to the attachment of these 

bearings so as to render the assembly more tolerant to any loss of tightening torque occurring at this stacked 

assembly. 

Pending the availability of this modification, and to verify the integrity of these screws the failure of which 

may in time lead to the loss of the non-rotating swashplate/rotating swashplate coupling, EUROCOPTER 

has rendered compliance with the periodic maintenance defined in Revision 1 of the ALERT TELEX 

mandatory. 

Revision 2 of ALERT TELEX No. 62.00.66 issued on October 26, 2005 informed you that the further 

analyses conducted by EUROCOPTER revealed that the loss of tightening torque on these screws leading 

to the deterioration of this coupling was related to creep of the peel shim. This plastic peel shim is used to 

adjust the bearing pre-loading between the non-rotating and the rotating swashplates. These analyses also 

demonstrated that the periodic check (every 100 flight hours) for presence of the attachment screws does 

not enable, in all cases, detection of the degradation of this coupling sufficiently early. 

EUROCOPTER has studied a new definition of the peel shim (stainless steel peel shim) to avoid the 

creeping phenomenon, on replacement of the attachment screws with a higher strength and on the increase 

of the tightening torque applied to these attachment screws. The purpose of this modification is to cancel the 

check specified above. 

Pending the availability of this modification, and to detect as soon as possible any attachment screw failure 

which may lead to the loss of the non-rotating swashplate/rotating swashplate coupling, EUROCOPTER has 

rendered compliance with the periodic maintenance defined in Revision 2 of the ALERT TELEX mandatory. 

This ALERT SERVICE BULLETIN informs you that EUROCOPTER has defined MOD 0743714 as set forth 

in Revision 2 of ALERT TELEX No. 62.00.66. 

This modification includes: 

- Replacement of the plastic peel shim by a stainless steel peel shim. 

- Improvement of the protection of the peel shim surface resting on the non-rotating swashplate. 

- New material used for the swashplate bearing attachment screws. 

- Increased tightening torque of these screws. 

- Increased pre-loading of the swashplate bearings. 

This modification will be embodied in an approved workshop through Reconditioning (RE) and/or Overhauls 

(RG) and will be entered in the log card of the Rotor Mast/Swashplate Assembly. 

This modification will eliminate the phenomenon that caused the failure of the swashplate bearing 

attachment screws, hence the periodic monitoring introduced by Revision 2 of ALERT TELEX No. 62.00.66 

issued on October 26, 2005. 
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1.E. COMPLIANCE 

The following measures are rendered mandatory from receipt of Revision 2 of this ALERT TELEX 

No. 62.00.66 issued on October 26, 2005. 

1.E.1. Compliance at the works 

1.E.1.a. On helicopters/installed equipment: Comply with paragraph 1.E.2.a. 

1.E.1.b. Non-installed equipment: Not applicable. 

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

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

On Rotor Mast assemblies having logged less than 750 flight hours since new or overhaul: 

- Comply with paragraph 2.B. no later than the 770-flight hour inspection, 

then, 

. comply with paragraph 2.B. every 25 flight hours. 

On Rotor Mast assemblies having logged 750 flight hours or more since new or overhauled: 

- For helicopters having embodied paragraph 2.B. for less than 5 flight hours, in compliance with 

revision 1 of ALERT TELEX No. 62.00.66 issued on July 13, 2005, 

. comply with paragraph 2.B at the latest within 25 flight hours after its last embodiment, 

then, 

. comply with paragraph 2.B. every 25 flight hours. 

- For helicopters having embodied paragraph 2.B. for more than 5 flight hours, in compliance with 

revision 1 of ALERT TELEX No. 62.00.66 issued on July 13, 2005, 

. Comply with paragraph 2.B within 20 flight hours following receipt of revision 2 of ALERT TELEX 

No. 62.00.66 issued on October 26, 2005. 

then, 

. comply with paragraph 2.B. every 25 flight hours. 

1.E.2.b. Non-Installed Equipment: On Rotor Mast assemblies having logged more than 750 flight hours: 

- Comply with paragraph 2.B. before installation on the helicopter. 

1.F. APPROVAL 

Approval is limited to civil version helicopters subject to an Airworthiness Certificate. 

The technical information contained in this Service Bulletin was approved on September 7, 2006 under the 

authority of EASA Design Organisation Approval No. 21J.056. 

1.G. MANPOWER 

Qualification : Mechanic. 

Time for the operations: 2 hours (approx). 
 ALERT SERVICE BULLETIN AS332 

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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 

Aircraft Maintenance Manual (MMA): Tasks 62-20-00-062 and 62-20-00-021. 

1.L. OTHER DOCUMENTS CONCERNED 

Maintenance Program (PRE). 

1.M. TOOLING CONCERNED 

Not applicable. 

1.N. INTERCHANGEABILITY AND MIXABILITY OF PARTS 

Not applicable. 
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2. ACCOMPLISHMENT INSTRUCTIONS 

2.A. GENERAL 

To ensure integrity of the 21 attachment screws of the swashplate bearings, EUROCOPTER provides you 

with two possible methods: 

- A visual method using a dentist‘s mirror. 

- A feel check method using a locally manufactured elbowed tool (6) (See Figure 1 DETAIL A) when the 

presence of bearing grease hinders visual check. 

2.B. OPERATIONAL PROCEDURE 

As per Figure 1: 

2.B.1. Preliminary Steps 

- Remove the 8 attachment screws (4) of sealing boot (1), as per MMA task 62-20-00-062, 

sub-task 62-20-00-031-004. 

2.B.2. Visual or feel check for the presence of the 21 attachment screw heads (2) under flange (3) 

First Method: 

- Raise washer (5) and boot (1) and using a dentist’s mirror, visually check that the 21 attachment screw 

heads (2) are present under flange (3): 

. Position the dentist’s mirror so that the attachment screw heads (2) can be viewed under flange (3). 

NOTE

When the screw heads (2) are masked by bearing grease, 

eliminate grease using a wood or plastic spatula to clear 

them. If the visual check is hindered by a too large amount of 

grease, apply the second method.

. Using a pencil, mark the location of one of the screw heads (2) on flange (3) . 

. Inspect the Rotor Mast all around to make sure that the 21 attachment screw heads (2) are present. 
 ALERT SERVICE BULLETIN AS332 

Approved under EASA DOA No. 21J.056. 62.00.66 Page 7/9

 2006.09.13

Second Method: 

- Raise washer (5) and boot (1), and using the elbowed tool (6), perform a feel check to make sure that the 

21 attachment screw heads (2) are present under flange (3): 

. Position the elbowed tool (6) (DETAIL A) so that the attachment screw heads (2) under flange (3) can be 

manually felt. 

. Using a pencil, mark the location of one of the screw heads (2) on flange (3). 

. Inspect the Rotor Mast all around to make sure that the 21 attachment screw heads (2) are present. 

Result Analysis

If the 21 attachment screw heads (2) are present: 

- Leave as is. 

- Comply with paragraph 2.B.3. 

- Resume flights. 

If at least one attachment screw head (2) is missing: 

- Remove the Rotor Mast assembly as per Task 62-20-00-021, sub-task 62-20-00-021-001 before resuming 

 flights. 

- Inform the Customer Service Technical Support Operations Department (STVM): 

. Tel: +33 (0) 4.42.85.96.24 

. Fax: +33 (0)4.42.85.99.66 

- Send the Rotor Mast assembly to an approved repair center for investigation and reconditioning. 

2.B.3. Final Steps 

- Relocate sealing boot (1), fit washer (5) and the 8 attachment screws (4) as per MMA task 62-20-00-062, 

sub-task 62-20-00-431-004. 

2.C. IDENTIFICATION 

- Record first compliance with this ALERT SERVICE BULLETIN on the log card of the Rotor Mast assembly. 

2.D. OPERATING AND MAINTENANCE INSTRUCTIONS 

Not applicable. 
 ALERT SERVICE BULLETIN AS332 

Approved under EASA DOA No. 21J.056. 62.00.66 Page 8/9

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Figure 1 
 ALERT SERVICE BULLETIN AS332 

Approved under EASA DOA No. 21J.056. 62.00.66 Page 9/9

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3. MATERIAL INFORMATION 

3.A. MATERIAL: COST - AVAILABILITY 

Not applicable. 

3.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT 

Not applicable. 

3.C. EQUIPMENT REQUIRED FOR EACH AIRCRAFT/ENGINE/COMPONENT 

Not applicable. 

3.D. PROCUREMENT CONDITIONS 

Order the required quantity (unless otherwise specified) 

from 

EUROCOPTER 

Etablissement de Marignane 

Sales & 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 

aircraft to be modified. 

4. APPENDIX 

Not applicable.