ASB No. AS365-05.00.60 

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Revision 2 2012-10-09 This document is available on the Internet: www.eurocopter.com/techpub

 Civil version(s): N1, N2, N3 

 Military version(s): F, Fi, K 

ALERT SERVICE BULLETIN 

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

Visual check of 10-blade and 11-blade TRH hubs 

ATA 64

Revision No. Date of issue 

Revision 0 2011-04-11 

Revision 1 2011-07-20 

Revision 2 2012-10-09 

Summary: 

The purpose of this ALERT SERVICE BULLETIN is to do a visual check of the 10-blade and 11-blade TRH hubs 

with removal of the Tail Gearbox (TGB) cover. 

Reason for last Revision:

The purpose of Revision 2 of this ALERT SERVICE BULLETIN is to extend the mandatory visual check of the tail 

rotor hub to AS365 helicopters equipped with an 11-blade TRH, only for version N3. 

Compliance: 

EUROCOPTER renders compliance with Revision 2 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 

For AS365 helicopter versions N1, N2, N3, F, Fi and K equipped with a 10-blade TRH, 

Helicopters equipped with a rotor hub P/N 365A33351100, 365A33351101 or 365A33351102. 

Only for AS365 helicopter version N3 equipped with an 11-blade TRH, 

Helicopters equipped with a rotor hub P/N 365A33216001 or 365A33216003. 

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, the technician found cracks 

on the TRH hub. 

Pending the results of additional investigations, EUROCOPTER recommended that you perform a visual 

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

Revision 1: 

Subsequent to a second case similar to the first case of cracks being detected on the TRH hub, and pending 

further investigation to determine the cause of these cracks, EUROCOPTER rendered mandatory the visual 

check of the 10-blade TRH hub, with removal of the TGB cover, every 55 flying hours. 

 Revision 2: 

The current analysis has led EUROCOPTER to extend the visual check of the rotor hub to AS365 

helicopters equipped with an 11-blade TRH, only for version N3. 

Revision 2 does not affect compliance with Revision 1 of this ALERT SERVICE BULLETIN, for helicopters 

equipped with a 10-blade TRH. 
 

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1.D. DESCRIPTION 

 Revision 0: 

Compliance with Service Bulletin Revision 0 consisted in performing a visual check, without removal of 

the 10-blade TRH hub, with removal of the TGB cover, at intervals not exceeding 110 flying hours. 

Revision 1: 

 Compliance with Revision 1 of this ALERT SERVICE BULLETIN consisted in rendering mandatory the visual 

check without removal of the 10-blade TRH hub, with removal of the TGB cover, every 55 flying hours. 

 Revision 2: 

 Compliance with Revision 2 of this ALERT SERVICE BULLETIN consists in: 

- Extending the mandatory visual check of the TRH hub to AS365 helicopters equipped with an 11-blade 

TRH, only for version N3. 

 - Integrating details on the check procedure in paragraph 3. 

1.E. COMPLIANCE 

1.E.1. Compliance at the works 

Not applicable. 

1.E.2. Compliance in service 

Helicopters/installed equipment: 

For helicopters equipped with a 10-blade TRH

Comply with paragraph 3. of this ALERT SERVICE BULLETIN before reaching 55 flying hours following 

receipt of Revision 1 of this ALERT SERVICE BULLETIN, issued on July 20, 2011. 

Then, 

Comply with paragraph 3. at intervals not exceeding 55 flying hours. 

For helicopters equipped with an 11-blade TRH (only version N3) 

Comply with paragraph 3. of this ALERT SERVICE BULLETIN before reaching 55 flying hours following 

receipt of Revision 2, issued on the date indicated at the bottom of the page, 

then, 

comply with paragraph 3. at intervals not exceeding 55 flying hours. 

Non-installed equipment: 

Not applicable 
 

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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 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 April 08, 2011 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 April 08, 2011 by the EUROCOPTER Airworthiness Department for export military versions. 

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

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

helicopters subject to an Airworthiness Certificate. 

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

on July 20, 2011 under the prerogatives of the recognition of design capability FRA21J-002-DGA for French 

Government helicopters. 

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

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

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

on October 09, 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 October 09, 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 October 09, 2012 by the EUROCOPTER Airworthiness Department for export military versions. 
 

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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 Mechanical 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 documents are necessary for compliance with this ALERT SERVICE BULLETIN: 

Maintenance Manual (MET): 

MET: 60.00.00.300: Rotors - General mechanical instructions 

MET: 64.21.01.402: TRH 365A33.0040 - Tail rotor assembly : Removal - Installation 

MET: 64.21.01.601: TRH 365A33.0040 - On-condition maintenance 

MET: 64.21.02.406: Quiet fenestron - Tail rotor hub body : Removal - Installation 

MET: 64.21.02.605: Quiet fenestron - Detailed inspection of the TRH 

MET: 64.21.02.606: Quiet fenestron - TRH inspection criteria 

Repair Manual (MRR): 

MRR: 64.21.01.726: Fit and clearances: Tail rotor 

Standard Practices Manual (MTC): 

MTC: 20.02.09.101: Crack detection through dye-penetrant inspection: General 

MTC: 20.07.03.401: Technical instructions - Instructions applicable during maintenance operations on 

mechanical assemblies 
 

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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 components, 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 1

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

the destination and the serial numbers of the helicopters to be 

modified. 

NOTE 2

For ALERT SERVICE BULLETINS, order by: 

Telex: HELICOP 410 969F 

Fax: +33 (0)4.42.85.99.96

2.B. INFORMATION CONCERNING INDUSTRIAL SUPPORT 

Not applicable. 
 

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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 

For a 10-blade TRH: 

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 

For an 11-blade TRH: 

Rotor hub A/R 365A33-2160-01 4 365A33-2160-01 Replace if cracks are 

detected 

Rotor hub A/R 365A33-2160-03 5 365A33-2160-03 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 

- Read and comply with the general mechanical instructions as per MET Work Card 60.00.00.300. 

- Read and comply with the maintenance instructions applicable to mechanical assemblies as per MTC Work 

Card 20.07.03.401. 

NOTE 1

The illustrations given in Figures 1 to 4 show a 10-blade 

TRH. The inspection areas visible on these illustrations are 

identical for 10-blade and 11-blade TRHs. 

3.B. OPERATIONAL PROCEDURE 

3.B.1. Preliminary steps (Figure 2) 

- Install the access equipment. 

- If necessary, release the rotor brake. 

- Remove the TGB fairing cover (b) (Detail B, Figure 2). 

3.B.2. Check for cracks (Figures 1 to 4)

- Using a light source, check for cracks on the entire Area C (Detail A, Figure 1) of the TRH hub (a) on the 

TGB (c) side (Detail C, Figure 2); pay particular attention around screws (e) (Detail A, Figure 1). 

 . Perform the check between the lower part of the TGB (c) and its fairing (d) (Details D and E, Figure 3). 

 . Turn the tail rotor by hand to check the entire Area C (Detail A, Figure 1). 

 - If in doubt on the presence of cracks: 

 . Remove the rotor hub (a) from the TRH: 

 - as per MET Work Card 64.21.02.406 for a 10-blade TRH. 

 - as per MET Work Card 64.21.01.402 for an 11-blade TRH. 

. Perform a non-destructive test. (Example: Dye-penetrant inspection as per MTC Work 

 Card 20.02.09.101 and Work Card 20.02.09.601). 

 

Interpretation of the results: 

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

. If necessary, install the TRH hub (a): 

- as per MET Work Card 64.21.02.406 for a 10-blade TRH. 

- as per MET Work Card 64.21.01.402 for an 11-blade TRH. 

. Comply with paragraph 3.B.3. 
 

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

. If necessary, remove the TRH hub (a): 

- as per MET Work Card 64.21.02.406 for a 10-blade TRH. 

- as per MET Work Card 64.21.01.402 for an 11-blade TRH. 

. Discard the TRH hub (a). 

. Perform a detailed check and a dimensional check of: 

- shouldered slide bushes (h) (Detail G, Figure 4), 

- clamping plate (g), 

- torsion bar bolts (j), 

- splined flange (f), 

as per MET Work Cards 64.21.02.605 and 64.21.02.606 for a 10-blade TRH, 

as per MET Work Card 64.21.01.601 and MRR Work Card 64.21.01.726 for an 11-blade TRH. 

 . Install: 

- a rotor hub (1), (2) or (3) as per MET Work Card 64.21.02.406 for a 10-blade TRH, 

- a rotor hub (4) or (5) as per MET Work Card 64.21.01.402 for an 11-blade TRH. 

. Inform immediately the Customer Service Technical Support Department by: 

Phone: + 33 (0)4.42.85.20.51 

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 (Figure 2)

- Install the TGB fairing cover (b) (Detail B, Figure 2). 

- If necessary, apply the rotor brake. 

- Remove the access equipment. 

3.C. IDENTIFICATION 

Identification of this document: 

- For helicopters equipped with a 10-blade TRH: 

 . Record initial compliance with Revision 1 of this ALERT SERVICE BULLETIN in the helicopter documents. 

- For helicopters equipped with an 11-blade TRH (only version N3): 

 . Record initial compliance with this ALERT SERVICE BULLETIN Revision 2 in the helicopter documents. 

3.D. OPERATING AND MAINTENANCE INSTRUCTIONS 

Not applicable. 
 

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For an 11-blade TRH, refer to NOTE 1 of paragraph 3.A.

Figure 1: TRH hub 

a

1

2

3 

4 

5 

TGB 

side 

Area C

e 

A - B - C 
 

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For an 11-blade TRH, refer to NOTE 1 of paragraph 3.A.

Figure 2: Location of the area to be checked (Area C) 

b 

c 

d 
 

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For an 11-blade TRH, refer to NOTE 1 of paragraph 3.A.

Figure 3: Visual check of Area C 

a 

1

2

3 

4 

5 

d 

c 

d 

c 

a 

1

2

3 

4 

5 

e 
 

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For an 11-blade TRH, refer to NOTE 1 of paragraph 3.A.

Figure 4: Detailed check and dimensional check 

j 

f 

g 

h