# ASB No. EC155-05A021

Revision 0 2011-04-11 Page 1/11

Revision 1 2011-07-20 This document is available on the Internet: www.eurocopter.com/techpub 

### Civil version(s): B, B1



# ALERT SERVICE BULLETIN

SUBJECT : TIME LIMITS - MAINTENANCE CHECKS - Tail Rotor Hub (TRH)

Visual check of the 10-blade TRH hub

ATA 64



### Revision No. Date of issue

Revision 0 2011-04-11

Revision 1 2011-07-20



### Summary :

The purpose of this Service Bulletin is to do a visual check of the 10-blade TRH hub with removal of the Tail

Gearbox (TGB) cover.



### Purpose of the last revision :

The purpose of revision 1 of this ALERT SERVICE BULLETI N is to render mandatory the visual inspection of the

10-blade TRH hub every 55 flight hours.



### Compliance :

EUROCOPTER renders compliance with revision 1 of this ALERT SERVICE BULLETIN mandatory For the attention of

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### 1. PLANNING INFORMATION

1.A. EFFECTIVITY

1.A.1. Helicopters/installed equipment

Helicopters equipped with a rotor hub P/N 365A33351100, 365A33351101

or 365A33351102 installed on the 10-blade Tail Rotor Hub (TRH) of the quiet fenestron tail rotor.

1.A.2. Non-installed equipment

Not applicable.



### 1.B. ASSOCIATED REQUIREMENTS

Not applicable.



### 1.C. REASON

Revision 0 :

During a 2T inspection on an AS365 helicopter equipped with a 10-blade TRH, t he technician found cracks

on the TRH hub.

Pending the results of additional investigations, EURO COPTER recommends that you do a visual check of

the 10-blade TRH hub, with removal of the Ta il Gearbox (TGB) cover, every 110 flying hours.

Revision 1 :

Subsequent to a second case similar to the first ca se of cracks being detected on the a 10-blade TRH hub,

and pending further investigation to determine the origin of such cracks, EUROCOPTER renders mandatory

the visual inspection of the 10-blade TRH hub, with removal of the TGB cover, every 55 flight hours.

Revision 1 of this ALERT SERVICE BULLETIN will form the subject of an EASA Airworthiness Directive.



### 1.D. DESCRIPTION

Revision 0 :

Compliance with this Service Bulletin consists in perf orming a visual check, without removal of the 10-blade

TRH hub, with removal of the TGB cover.

Revision 1 :

Revision 1 of this ALERT SERVICE BULLETIN consis ts in rendering mandatory the visual inspection,

without removal of the 10-blade TRH hub, with re moval of the TGB cover, every 55 flight hours.

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### 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. before reaching 55 flight h ours following receipt of revision 1 of this ALERT

SERVICE BULLETIN, issued on the date i ndicated at the foot of the page.

Then,

Comply with paragraph 3. at time in tervals not exceeding 55 flight hours.

Non-installed equipment :

Not applicable



### 1.F. APPROVAL

Approval of modifications :

Not applicable.

Approval of this document :

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

on April 08, 2011 under the prerogatives of the recogn ition of design capability FRA21J-002-DGA for French

Government helicopters.

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

on April 08, 2011 by the EUROCOPTER Airworthi ness Department for export military versions.

The technical information contained in Revision 1 of this ALERT SERVICE BU LLETIN was approved

on July 20, 2011 under the authority of EASA Design Organisation Appr oval No. 21J.056 for civil version

helicopters subject to an Ai rworthiness Certificate.

The technical information contained in Revision 1 of this ALERT SERVICE BU LLETIN was approved

on July 20, 2011 by the EUROCOPTER Airworthiness department for export military version helicopters.

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### 1.G. MANPOWER

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

personnel with the following qualification:

Qualification: 1 Mechanica l Engineering Technician.

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

Time for the operations: Approx. 1 hour for one mechanical engineering technician for the check.



### 1.H. WEIGHT AND BALANCE

Not applicable.



### 1.I. EFFECT ON ELECTRICAL LOADS

Not applicable.



### 1.J. SOFTWARE MODIFICATION EMBODIMENT RECORD

Not applicable.



### 1.K. REFERENCES

The following document is necessary for comp liance with this ALERT SERVICE BULLETIN:

- AMM: 64-20-04-061 - Tail rotor hub - Removal - Installation.

- AMM: 64-20-00-225 - TRH detailed inspection.

- AMM: 64-20-00-991 - TRH inspection criteria.



### 1.L. DOCUMENTS AFFECTED

Not applicable.



### 1.M. INTERCHANGEABILITY OR MIXABILITY OF PARTS

Not applicable.

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### 2. MATERIAL INFORMATION

2.A. MATERIAL: PRICE - AVAILABILITY - PROCUREMENT

Price

For any information concerning the kits and/or co mponents, contact the EUROCOPTER Network Sales &

Customer Relations Department.

Availability

The kits and/or components are delivered on the operator's order.

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

On the purchase order, please specify the mode of transport,

the destination and the serial numbers of the helicopters to be

modified.



### 2.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT

Not applicable.



### 2.C. MATERIAL REQUIRED FOR EACH HELICOPTER/COMPONENT

Kits or components to be ordered for one helicopter or one assembly :

Old Designation Qty New Part Number Item Part Number → Instructions

Rotor hub A/R 365A33-3511-00 1 365A33-3511 -00 Replace if cracks are detected

Rotor hub A/R 365A33-3511-01 2 365A33-3511 -01 Replace if cracks are detected

Rotor hub A/R 365A33-3511-02 3 365A33-3511 -02 Replace if cracks are detected

Products to be ordered separately :

Refer to the Tasks and Work Cards specified in this Service Bulletin.

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

Website: http://www.interturbine.com

Phone: +49.41.91.809.300

AOG: +49.41.91.809.444



### 2.D. MATERIAL TO BE RETURNED

Not applicable.

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### 3. ACCOMPLISHMENT INSTRUCTIONS

3.A. GENERAL

Not applicable.



### 3.B. OPERATIONAL PROCEDURE

3.B.1. Preliminary steps

- Install the access equipment.

- If necessary, release the rotor brake.

- Remove the TGB cover (b).

3.B.2. Check for cracks (Figures 1, 2 and 3)

- Using a light source, check for cracks the entire Area C of the TRH hub (a) on the TGB (c) side; pay

particular attention around screws (e).



### NOTE 1

The check must be done between the lower part of the TGB (c)

and its fairing (d) (see details D and E, Figure 3).



### NOTE 2

In order to check the entire Area C, turn the Tail Rotor (TR) by

hand.

Interpretation of the results :

- If no cracks are found on the TRH hub (a):

. Leave as is.

. Comply with paragraph 3.B.3.

- If cracks are found on the TRH hub (a):

. Remove the TRH hub (a) and replace it with a TRH hub (1), (2) or (3) as per AMM task 64-20-04-061.

. Perform a detailed check and a dimensional check of: (figure 4):

- shouldered slide bushes (4)

- clamping plate (5)

- torsion bar bolts (6)

- splined flange (7)

as per AMM tasks 64-20-00-225 and 64-20-00-991 .

. Inform immediately the Customer Serv ice Technical Support Department by:

Phone: + 33 (0)4.42.85.99.67

Fax: + 33 (0)4.42.85.99.66

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

. Comply with paragraph 3.B.3.

3.B.3. Final steps

Install the TGB cover (b).

If necessary, apply the rotor brake.

Remove the access equipment.

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### 3.C. IDENTIFICATION

Identification of this document :

- Record initial compli ance with revision 0 of this document in the helicopter documents.

- Record initial compli ance with revision 1 of this document in the helicopter documents.



### 3.D. OPERATING AND MAINTENANCE INSTRUCTIONS

Not applicable.

# ASB No. EC155-05A021

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Revision 1 2011-07-20 This document is available on the Internet: www.eurocopter.com/techpub Figure 1: TRH hub 

## TGB

side

Area C A A - B

a

1

2

3 e

# ASB No. EC155-05A021

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## b

c B

d

D

# ASB No. EC155-05A021

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## E

a

1

2

3 D

E a

1

2

3

d

d c c

e

# ASB No. EC155-05A021

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### DETAIL A



## A DETAIL A

6

7

5 4