ASB No. AS350-65.00.46

Revision 0 2011-05-18 Approved under EASA DOA No. 21J.056. Page 1/11 

This document is available on the internet: www.eurocopter.com/techpub 

 Civil version(s): B, BA, BB, B1, B2, B3, D 

 Military version(s): L1 

ALERT SERVICE BULLETIN 

SUBJECT: ROTOR FLIGHT CONTROLS – Tail gearbox 

 Check of the Tail gearbox (TGB) casing assembly. 

Revision No. Date of issue 

Revision 0 2011-05-18 

Summary: 

To perform a non-destructive inspection (for example a dye-penetrant inspection) of the attachment yokes of the 

control lever of the TGB casing assembly in order to check for cracks. 

Compliance: 

EUROCOPTER renders compliance with this ALERT SERVICE BULLETIN mandatory. 

For the attention of 
 

ASB No. AS350-65.00.46

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1. PLANNING INFORMATION 

1.A. EFFECTIVITY 

1.A.1. Helicopters/installed equipment 

Tail gearboxes (TGB) equipped with TGB casing assembly MP/N 350A33-1090-02 with 

the following serial numbers: 

MA47577, MA47585, MA47587, MA47588, MA47589, MA47590, MA47591, MA47592, MA47593, 

MA47597, MA47598, MA47599, MA47600, MA47602, MA47604, MA47606, MA47610, MA47613, 

MA47615, MA47617, MA47619, MA47620, MA47621, MA47622, MA47623, MA47624, MA47626, 

MA47628, MA47631. 

NOTE 

Refer to the Log card (FM) of the TGB to identify the actual configuration of the 

helicopter. 

1.A.2. Non-installed equipment 

TGB casing assemblies listed in paragraph 1.A.1. 

1.B. ASSOCIATED REQUIREMENTS 

Not applicable. 

1.C. REASON 

Following repair of the manufacturing mold from the TGB casing assemblies, the dye-penetrant inspection 

performed after machining of the attachment yokes of the control lever has revealed cracks on some TGB 

casing assemblies. 

EUROCOPTER has identified the TGB casing assemblies which may show cracks. 

The presence of cracks on at least one of the attachment yokes of the control lever can lead to the loss of tail 

rotor pitch control. 

This is the reason why EUROCOPTER renders the check for cracks in the attachment yokes of the control 

lever of the TGB casing assemblies mandatory, by introducing a non-destructive inspection (for example a 

dye-penetrant inspection). 

Revision 0 of this ALERT SERVICE BULLETIN will form the subject of an EASA Airworthiness Directive. 

1.D. DESCRIPTION 

Compliance with this ALERT SERVICE BULLETIN consists in disassembling the control lever in order to 

perform a non-destructive inspection (for example a dye-penetrant inspection) of the attachment yokes of the 

control lever and, if necessary, replace the TGB. 
 

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1.E. COMPLIANCE 

1.E.1. Compliance at the works 

The operations are to be carried out by EUROCOPTER. 

Helicopters/installed equipment: 

Comply with paragraph 3. before delivery. 

 Non-installed equipment: 

Comply with paragraph 3.B.2. before delivery. 

1.E.2. Compliance in service 

The operations on the helicopter are to be performed by the operator. 

The operations on non-installed equipment are to be performed by the operator. 

Helicopters/installed equipment: 

For TGB casings having logged less than 550 flying hours since new: 

Comply with paragraph 3. of this ALERT SERVICE BULLETIN at the latest when reaching 660 flying hours 

or 26 months since new (the first limit reached is applicable). 

For TGB casings having logged more than 550 flying hours since new: 

Comply with paragraph 3. of this ALERT SERVICE BULLETIN within 110 flying hours or no later than 

within 13 months following receipt of this ALERT SERVICE BULLETIN, issued on the date indicated at the 

bottom of the page. 

 Non-installed equipment: 

Comply with paragraph 3.B.2. before installation on the helicopter and no later than within 12 months 

following receipt of this ALERT SERVICE BULLETIN, issued on the date indicated at the bottom of the page. 

1.F. APPROVAL 

 Approval of modifications: 

Not applicable. 

 Approval of this document: 

The technical information contained in this ALERT SERVICE BULLETIN Revision 0 was approved 

on May 17, 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 ALERT SERVICE BULLETIN Revision 0 was approved 

on May 17, 2011 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 0 was approved 

on May 17, 2011 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: approximately 2 hours for one Mechanical Engineering Technician. 

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. 

MTC: 20.02.09.101 – Crack detection – General principles applicable to the dye-penetrant inspection 

procedure 

MTC: 20.02.09.601 – Crack detection – Checking structural parts and components using the dye-penetrant 

inspection procedure 

MTC: 20.04.01.401 – Cleaning – Cleaning mechanical parts 

MTC: 20.04.02.401 – Stripping – Stripping organic surface coatings 

MTC: 20.04.04.403 – Surface treatment before painting – Surface treatment chemical conversion with 

"Alodine 1200" 

MTC: 20.04.05.101 – Paint and primer application procedure – General information concerning painting 

means and paint touch-ups 

MTC: 20.04.05.402 – Paint and primer application procedure – EPOXY primer P05 – P20 scheme 

MTC: 20.04.05.403 – Paint and primer application procedure – Paint scheme 4080 

MTC: 20.04.05.601 – Paint and primer application procedure – Checks after paint application 

MTC: 20.08.05.101 – General rules applicable to aircraft – Raising and updating the equipment log card 

(F.M.E.) for equipment follow-up 

For AS350 helicopter versions B2 and B3: 

AMM: 60-00-00, 3-1 – General instructions - Mechanics 

AMM: 65-21-00, 4-1 – TGB removal 

AMM: 65-21-00, 4-2 – TGB installation 

For AS350 helicopter versions B, BA, BB, B1, D and L1: 

MET: 60.00.00.301 – Rotors – General – General instructions 

MET: 65.20.00.401 – Tail gearbox – TGB, tail rotor hub and control plate – Removal-Installation 
 

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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 all information concerning kits and/or components, contact the Sales and Customer Relations 

Department of the EUROCOPTER Network. 

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. 

2.C. MATERIAL REQUIRED FOR EACH HELICOPTER/COMPONENT 

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

Former Designation Qty New P/N Item 

No. P/N Instructions 

 

Tail gearbox A/R 350A33-0200-06 1 / / 

Tail gearbox A/R 350A33-0200-07 2 / / 
 

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 Products to be ordered separately: 

Designation Qty Product P/N CM Item 

No. 

Chemical conversion agent (Alodine 1200) A/R N8716206112 CM 316 3 

EPOXY Primer (P05) A/R DHS186-111-20 CM 487 4 

Top coat paint (P81) A/R 4080 CM 498 5 

Refer to the table above and the Work Cards and Tasks specified 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 

If a crack is found on at least one of the control lever yokes of the TGB casing assembly, return the TGB to 

EUROCOPTER in accordance with the procedure described in Service Letter No. 1567-00-02. 
 

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3. ACCOMPLISHMENT INSTRUCTIONS 

3.A. GENERAL 

Read and comply with the general mechanical instructions as per AMM Task 60-00-00, 3-1. 

Read and comply with the general instructions concerning the rotors as per MET Work Card 60.00.00.301. 

Read and comply with the general information concerning painting means and paint touch-ups as per 

MTC Work Card 20.04.05.101. 

3.B. OPERATIONAL PROCEDURE 

3.B.1. Preliminary steps 

Install the access equipment. 

3.B.2. Check for cracks in input yokes (a) of TGB casing assembly (d) (Figures 1 and 2)

- Remove control lever (b) (Figure 1) as per AMM Task 65-21-00, 4-1 or MET Work Card 

65.20.00.401. 

- Strip the areas to be inspected (Z) (Figure 2) as per MTC Work Card 20.04.02.401. 

- Perform a non-destructive inspection of each area to be inspected (Z) (for example a dye-penetrant 

inspection as per MTC Work Cards 20.02.09.101 and 20.02.09.601). 

- Check for cracks in the inspected areas (Z): 

. If there is a crack in at least one of the inspected areas (Z): 

- Remove TGB (c) as per AMM Task 65-21-00, 4-1 or MET Work Card 65.20.00.401. 

- Install a TGB (1) or (2) as per AMM Task 65-21-00, 4-2 or MET Work Card 65.20.00.401. 

- Contact the Customer Service Technical Support Department by: 

Tel.: + 33 (0)4 42 85 99 51 

Fax: + 33 (0)4 42 85 99 66. 

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

- Return TGB (c) to EUROCOPTER in accordance with paragraph 2.D. 

. If there is no crack in all of the inspected areas (Z): 

- Clean the inspected areas (Z) as per MTC Work Card 20.04.01.401. 

- Do a treatment with Alodine 1200 (3) (not represented) on the surfaces of the inspected areas (Z) as 

per MTC Work Card 20.04.04.403. 

- Apply EPOXY P05 primer (4) (not represented) to the inspected areas (Z) as per MTC Work 

Card 20.04.05.402. 

- Apply grey P81 top coat paint (5) (not represented) to the inspected areas (Z) as per MTC 

Work Card 20.04.05.403. 

- Do the check after application of paint to the inspected areas (Z) as per MTC Work Card 

20.04.05.601. 

- Install control lever (b) as per AMM Task 65-21-00, 4-2 or MET Work Card 65.20.00.401. 

3.B.3. Final steps 

Remove the access equipment. 
 

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3.C. IDENTIFICATION 

 Identification of this document: 

Record compliance with this ALERT SERVICE BULLETIN on the log card (FM) of the TGB as per MTC Work 

Card 20.08.05.101. 

3.D. OPERATING AND MAINTENANCE INSTRUCTIONS 

Not applicable. 
 

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Figure 1: Control lever 

A

A

b 

c 

1 ou/or 2 

a 

B (see Figure 2) 
 

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Figure 2: TGB casing assembly (front view) 

B

Z 

d 

Z 

a 

(see Figure 1)