EASB

Revision 0 2012-09-19 Page 1/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

EMERGENCY

ALERT SERVICE BULLETIN

SUBJECT: TIME LIMITS - MAINTENANCE CHECKS 

Check of the Tail Rotor laminated half bearings 

 ATA: 05, 64 

AIRCRAFT 

CONCERNED NUMBER Version(s) 

Civil Military

AS350 05.00.71 B, BA, BB, D, B1, B2, B3 L1 

AS355 05.00.63 E, F, F1, F2, N, NP 

AS550 05.00.46 A2, C2, C3, U2 

AS555 05.00.42 AF, AN, SN, UF, UN 

Revision No. Date of issue 

Revision 0 2012-09-19 

Revision 1 2012-11-26 

Revision 2 2012-12-19 

Summary: 

The purpose of this ALERT SERVICE BULLETIN is to make the periodic check of the laminated half bearings 

mandatory. 

Reason for last Revision: 

The purpose of Revision 2 is: 

- to extend the applicability to all laminated half bearing part numbers. 

- to specify permissible criteria for laminated half bearings in the table of paragraph 3.B.2. 

Compliance: 

Compliance with this ALERT SERVICE BULLETIN is mandatory. 

For the attention of
 

 EASB

Revision 0 2012-09-19 Page 2/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

1. PLANNING INFORMATION 

1.A. EFFECTIVITY 

1.A.1. Helicopters/installed equipment 

On helicopters equipped with a tail rotor PRE MOD 075601 on which laminated half bearings (all part 

numbers) are installed. 

NOTE 1 

The laminated half bearings installed on helicopters 

equipped with a tail rotor POST MOD 075601 are subject to 

compliance with ALERT SERVICE BULLETINS 

No. 01.00.65 (AS350 version B3 “e”) and 

No. 01.00.24 (AS550 version C3 “e”). 

1.A.2. Non-installed equipment 

Not applicable. 

1.B. ASSOCIATED REQUIREMENTS 

Not applicable. 

1.C. REASON 

Revision 0: 

Premature cracks in laminated half bearings equipping Tail Rotor blades have recently been detected on

several AS350 B3 helicopters POST MOD 075601. 

Because the laminated half bearing deteriorates progressively, EUROCOPTER has issued Safety 

Information Notice No. 2482-S-64 to remind all operators of the particular attention that must be given during 

the visual check of the elastomeric part of the laminated half bearings during the ALF check. 

Deterioration of this part can generate in-flight vibrations, felt mainly in the pedals, requiring the pilot to land 

as soon as possible. 

In order to prevent the occurrence of in-flight vibrations, EUROCOPTER issues this Service Bulletin to

enhance the laminated half bearing inspection procedure so as to detect any deterioration of the bearings as 

early as possible. 

EUROCOPTER is conducting all the necessary investigations with operators and the supplier of the 

laminated half bearings in order to identify the cause of the phenomenon. 

Revision 1: 

Following further analyses, EUROCOPTER confirmed that the reason for the behavior of the laminated half 

bearings proving at times to be faulty was related to the embodiment of modification 075601. 

For this reason, EUROCOPTER issued ALERT SERVICE BULLETINS No. 01.00.65 (AS350 version B3 “e”) 

and No. 01.00.24 (AS550 version C3 “e”) concerning the maintenance to be applied to helicopters equipped 

with a Tail Rotor POST MOD 075601. 
 

 EASB

Revision 0 2012-09-19 Page 3/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

Furthermore, the analyses conducted following the event described in Safety Information Notice 

No. 2507-S-64 lead EUROCOPTER to reconsider the function of the laminated half bearings. Consequently,

EUROCOPTER makes the periodic check of the laminated half bearings mandatory. 

This decision is formalized by converting Service Bulletins No. 05.00.71 (AS350), No. 05.00.63 (AS355), 

No. 05.00.46 (AS550) and No. 05.00.42 (AS555) into ALERT SERVICE BULLETINS. 

Moreover, Revision 1 of this ALERT SERVICE BULLETIN specifies the criteria for replacement of the 

laminated half bearings for helicopters equipped with a tail rotor PRE MOD 075601. 

Revision 1 of this ALERT SERVICE BULLETIN affects compliance with Revision 0. 

Revision 2: 

The purpose of Revision 2 is: 

- to extend the applicability to all laminated half bearing part numbers. 

- to specify permissible criteria for laminated half bearings in the table of paragraph 3.B.2. 

1.D. DESCRIPTION 

- Check to make sure there is no deterioration of the laminated half bearings. 

- Interpretation of the results. 

1.E. COMPLIANCE 

1.E.1. Compliance at the works 

Not applicable. 

1.E.2. Compliance in service 

Helicopters/installed equipment: 

Comply with paragraph 3. of this ALERT SERVICE BULLETIN at the latest after the last flight of the day

(ALF) following receipt of Revision 2 of this ALERT SERVICE BULLETIN, issued on the date indicated at the 

bottom of the page. 

Then, 

Comply with paragraph 3. of this ALERT SERVICE BULLETIN after each last flight of the day (ALF) without 

exceeding 10 flying hours between two checks. 

 Non-installed equipment: 

Not applicable. 

1.F. APPROVAL 

 Approval of modifications: 

Not applicable. 
 

 EASB

Revision 0 2012-09-19 Page 4/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

 Approval of this document: 

The technical information contained in this Service Bulletin Revision 0 was approved 

on September 19, 2012 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 Service Bulletin Revision 0 was approved 

on September 19, 2012 under the prerogatives of the recognition of design capability FRA21J-002-DGA for 

French Government helicopters. 

The technical information contained in this Service Bulletin Revision 0 was approved 

on September 19, 2012 by the EUROCOPTER Airworthiness Department for export military versions. 

The technical information contained in this ALERT SERVICE BULLETIN Revision 1 was approved 

on November 26, 2012 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 1 was approved 

on November 26, 2012 under the prerogatives of the recognition of design capability FRA21J-002-DGA for

French Government helicopters. 

The technical information contained in this ALERT SERVICE BULLETIN Revision 1 was approved 

on November 26, 2012 by the EUROCOPTER Airworthiness Department for export military versions. 

The technical information contained in this ALERT SERVICE BULLETIN Revision 2 was approved 

on December 19, 2012 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 2 was approved 

on December 19, 2012 under the prerogatives of the recognition of design capability FRA21J-002-DGA for

French Government helicopters. 

The technical information contained in this ALERT SERVICE BULLETIN Revision 2 was approved 

on December 19, 2012 by the EUROCOPTER Airworthiness Department for export military versions. 

1.G. MANPOWER 

For compliance with this ALERT SERVICE BULLETIN, EUROCOPTER recommends the following personnel 

qualifications: 

Qualification: 1 Mechanical Aircraft Technician or 1 crew member who has received an appropriate training 

by the operator’s maintenance organization, if authorized by local authorities. 

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

Time for the operations: approximately 5 minutes for the check. 

1.H. WEIGHT AND BALANCE 

Not applicable. 
 

 EASB

Revision 0 2012-09-19 Page 5/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

1.I. EFFECT ON ELECTRICAL LOADS 

Not applicable. 

1.J. SOFTWARE MODIFICATION EMBODIMENT RECORD 

Not applicable. 

1.K. REFERENCES 

The documents required for compliance with this ALERT SERVICE BULLETIN are as follows: 

For AS350 helicopter versions BA, BB, B, D, L1, B1, AS550 helicopter versions A2, C2, U2 and all 

AS355 and AS555 helicopter versions: 

MRR: 64.10.00.704: Tail rotor blades - Replacing the laminated bearings (before application of 

MOD 07 5552) 

MRR: 64.10.00.771: Tail rotor blades - Mounting/Removal of tail rotor transmission 

For AS350 helicopter versions B2, B3 and AS550 helicopter version C3: 

AMM: 64-10-00,4-3: Tail rotor blade: Removal - Laminated main bearing 

AMM: 64-10-00,4-4: Tail rotor blade: Installation - Laminated bearings 

1.L. DOCUMENTS AFFECTED 

EUROCOPTER will modify the following documents with respect to this Service Bulletin: 

- Maintenance Manual (MET), 

- Aircraft Maintenance Manual (AMM), 

- Master Servicing Manual (MSM). 

The documents affected will be updated as part of a future revision. 

1.M. INTERCHANGEABILITY OR MIXABILITY OF PARTS 

 Not applicable. 
 

 EASB

Revision 0 2012-09-19 Page 6/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

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 and Tasks referenced in this ALERT SERVICE BULLETIN. 

 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.
 

 EASB

Revision 0 2012-09-19 Page 7/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

3. ACCOMPLISHMENT INSTRUCTIONS 

3.A. GENERAL 

Not applicable. 

3.B. OPERATIONAL PROCEDURE 

3.B.1. Check of the laminated half bearings 

Pressure face: 

- Position both Tail Rotor blades horizontally. 

- Apply an axial perpendicular load (F) to one Tail Rotor blade (a) (See Figure 1). 

NOTE 1 

The load must be applied by hand to the pressure face of the 

blade, taking care not to reach the extreme position against the 

tail rotor hub. 

- While maintaining the load, visually check all the visible faces of the laminated half bearings (front face and 

side faces) in area B of DETAIL A, in order to detect either of the following: 

 . separation between the elastomer and the metal parts (see example in Figure 3), 

 . a crack in the elastomer (see example in Figure 4), 

 . extrusion (see example in Figure 4). 

NOTE 2 

A flashlight can be used to facilitate the check. 

- Interpret the results in accordance with paragraph 3.B.2. 

- Repeat the operation by applying the same load to the other blade in order to check the other laminated 

half bearing, then interpret the results in accordance with paragraph 3.B.2. 

Suction face: 

- Stand between the rotor and the tail boom. 

- Apply an axial perpendicular load (G) to one Tail Rotor blade (a), on the suction face side (See Figure 2). 

NOTE 3 

The load must be applied by hand to the suction face of the 

blade. 

- While maintaining the load, visually check all the visible faces of the laminated half bearings (front face 

and side faces) in area C (Figure 2), in order to detect extrusion (see example in Figure 4). 

NOTE 4 

A flashlight can be used to facilitate the check. 

- Interpret the results in accordance with paragraph 3.B.2. 

- Repeat the operation by applying the same load to the other blade in order to check the other laminated 

half bearing, then interpret the results in accordance with paragraph 3.B.2. 
 

 EASB

Revision 0 2012-09-19 Page 8/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

3.B.2. Interpretation of the results (Figures 3 and 4) 

 - If there is no separation, crack or extrusion, no maintenance is required. 

- If there is separation, a crack or extrusion, refer to the following criteria: 

Permissible deterioration 

without repair 

Repair Deterioration requiring replacement

Laminated 

bearings 

(Figures 3 and 

4) 

Laminated 

area 

Separations and/or cracks: 

Deteriorations permitted as 

long as the criteria requiring 

replacement are not 

reached 

None Continuous deterioration > : 

L > 5mm (.196 in.) and P > 2mm (.078 in.) 

(See Figure 3)

- replacement of the damaged component 

(as per AMM 64-10-00,4-3 and 

64-10-00,4-4 or MET 64.10.00.704 and 

64.10.00.771) 

Colors (shiny marks) on the 

side faces 

None Deterioration permitted 

Marks without cracks None Deterioration permitted 

Extrusion without separation 

or crack meeting the 

replacement criteria as per 

column “Deterioration 

requiring replacement” 

Remove the extrusion 

particles with your finger (if 

possible). 

Monitor that there is no 

separation or crack in 

accordance with the 

replacement criteria as per 

column “Deterioration 

requiring replacement” 

None 

Extrusion with separation or crack 

meeting the above replacement criteria 

3.C. IDENTIFICATION 

 Identification of this document: 

 Record initial compliance with this document in the helicopter documents. 

3.D. OPERATING AND MAINTENANCE INSTRUCTIONS 

 Not applicable. 

 
 

 EASB

Revision 0 2012-09-19 Page 9/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

Figure 1 

A

DETAIL A 

B

F 

F 

a 

B
 

 EASB

Revision 0 2012-09-19 Page 10/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

Figure 2 

G 

G 

C

a 
 

 EASB

Revision 0 2012-09-19 Page 11/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

Figure 3 

Example of 

separation 
 

 EASB

Revision 0 2012-09-19 Page 12/12 

Revision 2 2012-12-19 This document is available on the internet: www.eurocopter.com/techpub

Figure 4 - Example of extrusion (continuous line) and cracks (dotted line)

Example of crack 

Example of extrusion 

Example of extrusion