EASA AD No.: 2015-0177

TE.CAP.00110-004 © European Aviation Safety Agency. All rights reserved. 1/2

Proprietary document. Copies are not controlled. Confirm revision status through the EASA-Internet/Intranet.

EASA AIRWORTHINESS DIRECTIVE

AD No.: 2015-0177

Date: 25 August 2015

Note: This Airworthiness Directive (AD) is issued by EASA, acting in accordance with Regulation 

(EC) No 216/2008 on behalf of the European Community, its Member States and of the European 

third countries that participate in the activities of EASA under Article 66 of that Regulation.

This AD is issued in accordance with EU 748/2012, Part 21.A.3B. In accordance with EU 1321/2014 Annex I, Part M.A.301, the 

continuing airworthiness of an aircraft shall be ensured by accomplishing any applicable ADs. Consequently, no person may operate an 

aircraft to which an AD applies, except in accordance with the requirements of that AD, unless otherwise specified by the Agency

[EU 1321/2014 Annex I, Part M.A.303] or agreed with the Authority of the State of Registry [EC 216/2008, Article 14(4) exemption].

Design Approval Holder’s Name:

TURBOMECA

Type/Model designation(s):

ARRIEL 2 engines

TCDS Number: EASA.E.001

Foreign AD: Not applicable

Supersedure: None

ATA 72 Engine – Torque Conformation Box – Check

Manufacturer(s): Turboméca S.A.

Applicability: ARRIEL 2C, 2C1, 2C2, 2S1 and 2S2 engines, all serial numbers, if incorporating

Turboméca modification (mod) TU 34 or mod TU34A – “Torque conformation box, 

increase of resistance to temperature”.

These engines are known to be installed on, but not limited to, Airbus Helicopters

AS 365 N3, EC155 B/B1 and Sikorsky S-76C+, S76C++ helicopters.

Reason: Several cases of torque conformation box (TCB) failures have been reported on 

engines incorporating mod TU34 or mod TU34A. Investigation concluded that 

these failures were caused by cracks on soldered joints of TCB resistors. 

This condition, if not corrected, could lead to limited power availability in a One 

Engine Inoperative (OEI) case, possibly resulting in reduced control of the 

helicopter.

To address this unsafe condition, Turboméca issued Mandatory Service Bulletin 

(MSB) 292 72 2860 version A providing instructions for TCB checks.

For the reasons described above, this AD requires repetitive TCB checks and, 

depending on findings, replacement of the TCB with a serviceable one. This AD 

also provides an optional terminating action for the required repetitive checks.

Effective Date: 08 September 2015
EASA AD No.: 2015-0177

TE.CAP.00110-004 © European Aviation Safety Agency. All rights reserved. 2/2

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Required Action(s) 

and Compliance

Time(s):

Required as indicated, unless accomplished previously:

(1) Within 600 engine flight hours (EH), or 6 months, whichever occurs first after 

the effective date of this AD, and, thereafter, at intervals not to exceed 600 

EH, accomplish a torque conformation check (comprising two torque 

conformation box resistance values checks) in accordance with the 

instructions of Turboméca MSB 292 72 2860.

Note: A non-cumulative tolerance of 10% may be applied to the compliance times 

specified in paragraph (1) of this AD to allow synchronisation of the required 

inspections with other maintenance tasks for which a non-cumulative tolerance is 

already granted in the applicable Engine Maintenance Manual.

(2) If, during any check as required by paragraph (1) of this AD, any discrepancy 

is identified, before next flight, replace the affected TCB with a serviceable 

one in accordance with the instructions of Turboméca MSB 292 72 2860.

(3) Replacement of the TCB on an engine with a serviceable TU34 or TU34A 

TCB does not constitute terminating action for the repetitive checks required 

by paragraph (1) of this AD for that engine.

(4) Modification of an engine in accordance with the instructions of Turboméca 

SB 292-72-2188 constitutes terminating action for the repetitive checks as 

required by paragraph (2) of this AD for that engine, provided that, following 

modification, no mod TU34 TCB or mod TU34A TCB is re-installed on that 

engine.

Ref. Publications: Turboméca MSB 292 72 2860 version A dated 15 July 2015.

Turboméca MSB 292 72 2188 version A dated 02 July 2015.

The use of later approved revisions of these documents is acceptable for 

compliance with the requirements of this AD.

Remarks: 1. If requested and appropriately substantiated, EASA can approve Alternative 

Methods of Compliance for this AD.

2. This AD was posted on 22 July 2015 as PAD 15-094 for consultation until 19

August 2015. The Comment Response Document can be found at 

http://ad.easa.europa.eu.

3. Enquiries regarding this AD should be referred to the Safety Information 

Section, Certification Directorate, EASA. E-mail: ADs@easa.europa.eu.

4. For any question concerning the technical content of the requirements in this 

AD, please contact:

Turboméca S.A., ARRIEL 2 Customer Support

40220 Tarnos, France

Fax: +33 5 59 74 45 15, or your usual or nearest TURBOMECA technical 

representative (refer to http://www.turbomeca-support.com).