### 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 C EDEX F RANCE 

### 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 t he 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 s ubject 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 scr ew 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 a ssembly had been returned and investigated at EUROCOPTER. The investigations demonstrated that the ruptures detected on all the screws were progressive failures due to fatigue.

### ALERT SERVICE BULLETIN AS332

Approved under EASA DOA No. 21J.056. 

# 62.00.66 Page 3/9

2006.09.13 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 t heir progressive fatigue rupture. EUROCOPTER has continued these analyses and has studi ed 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 veri fy the integrity of these screws the failure of which may in time lead to the loss of the non-rotating sw ashplate/rotating swashplate coupling, EUROCOPTER has rendered compliance with the periodic maint enance 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 cr eep 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 presenc e of the attachment screws does not enable, in all cases, detection of the degr adation 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 det ect as soon as possible any attachment screw failure which may lead to the loss of the non-rotating swashpl ate/rotating swashplate coupling, EUROCOPTER has rendered compliance with the periodic maintenance defi ned 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 sh im 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 wo rkshop 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 in troduced by Revision 2 of ALERT TELEX No. 62.00.66 issued on October 26, 2005.

### ALERT SERVICE BULLETIN AS332

Approved under EASA DOA No. 21J.056. 

# 62.00.66 Page 4/9

2006.09.13 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 equi pment: 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 fli ght 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 with in 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 mo re 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 helicopter s subject to an Airworthiness Certificate.

The technical information contained in this Serv ice 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

Approved under EASA DOA No. 21J.056. 

# 62.00.66 Page 5/9

2006.09.13 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.

### ALERT SERVICE BULLETIN AS332

Approved under EASA DOA No. 21J.056. 

# 62.00.66 Page 6/9

2006.09.13 

### 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 mirro r, visually check that the 21 attachment screw

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

. Position the dentist’s mirror so that the attach ment 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 Ta sk 62-20-00-021, sub-task 62-20-00-021-001 before resuming flights.

- Inform the Customer Service Technica l 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 r epair 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 BU LLETIN 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

2006.09.13 Figure 1

### ALERT SERVICE BULLETIN AS332

Approved under EASA DOA No. 21J.056. 

# 62.00.66 Page 9/9

2006.09.13 

### 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.