EASA AD No.: 2011-0249 

EASA Form 110 Page 1/2

EASA AIRWORTHINESS DIRECTIVE 

AD No.: 2011-0249 

Date: 22 December 2011 

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 EC 1702/2003, Part 21A.3B. In accordance with EC 2042/2003 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 [EC 

2042/2003 Annex I, Part M.A.303] or agreed with the Authority of the State of Registry [EC 216/2008, Article 14(4) exemption]. 

Type Approval Holder’s Name : 

TURBOMECA 

Type/Model designation(s) : 

ARRIEL 2 series engines 

TCDS Number : EASA E.001 

Foreign AD : Not applicable 

Supersedure : None 

ATA 73 Engine Fuel & Control – Digital Engine Control Unit (DECU) – 

Identification / Replacement 

Manufacturer(s): TURBOMECA 

Applicability: ARRIEL 2C1, 2C2 and 2S2 turboshaft engines, all serial numbers. 

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

EC 155 B, EC 155 B1 and Sikorsky S-76C helicopters.

Reason: An incident has been reported of a helicopter which experienced a Digital 

Engine Control Unit (DECU) malfunction in flight from one of its ARRIEL 2C1 

engines. The indicating system of the helicopter displayed a “FADEC FAIL” 

message, with a concurrent loss of automatic control of the engine. The mission 

was aborted and the helicopter returned to its base without any further incident. 

The subsequent technical investigations carried out by Turboméca revealed that 

a Digital Engine Control Unit (DECU) assembly non-conformity was at the origin 

of this event. Further investigations performed with the supplier of the DECU led 

to the conclusion that only a limited number of DECU are potentially affected by 

this non-conformity. 

This condition, if not corrected, could lead to a loss of automatic control on one 

or both engines installed on the same helicopter, potentially resulting in an 

emergency landing of the helicopter. 

For the reasons described above, this AD requires replacement of each affected 

DECU with a serviceable part. This AD also prohibits the installation of any 

unserviceable DECU on an engine. 

Effective Date: 05 January 2012 
EASA AD No.: 2011-0249 

EASA Form 110 Page 2/2

Required Action(s) 

and Compliance 

Time(s): 

Required as indicated, unless accomplished previously: 

(1) Within 50 Engine Hours (EH) after the effective date of this AD, determine if 

at least one of the engines installed on the helicopter is equipped with a 

DECU whose serial number (s/n) is listed in the Table (Figure) of 

Turboméca Mandatory Service Bulletin (MSB) A292 73 2845 version A. 

(2) For any helicopter fitted with two DECUs whose s/n are listed in the Table 

(Figure) of Turboméca Mandatory Service Bulletin (MSB) A292 73 2845 

version A, within 50 EH after the effective date of this AD, replace one of 

the two DECUs with a serviceable part. 

(3) For any helicopter fitted with one DECU whose s/n is listed in the Table 

(Figure) of Turboméca MSB A292 73 2845 version A, within 1 000 EH or 12 

months, whichever occurs first after the effective date of this AD, replace 

the affected DECU with a serviceable part. 

(4) From the effective date of this AD, do not install a DECU whose s/n is listed 

in Table (Figure) of Turboméca MSB A292 73 2845 version A on an engine, 

and do not install an engine having a DECU installed whose s/n is listed in 

Table (Figure) of Turboméca MSB A292 73 2845 version A on a helicopter, 

unless the DECU is serviceable. 

Definition: 

For the purpose of this AD, a serviceable DECU is: 

• A part not having a s/n listed in the Table (Figure) of Turboméca MSB A292 

73 2845 version A, or

• A part having a s/n listed in the Table (Figure) of MSB A292 73 2845 version 

A, provided this DECU has passed the inspection in accordance with the 

instructions of Turboméca MSB No. A292 73 2845 version A. 

Ref. Publications: TURBOMECA MSB A292 73 2845 version A, dated 19 December 2011. 

The use of later approved revisions of this document 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. The required actions and the risk allowance have granted the issuance of a 

Final AD with Request for Comments, postponing the public consultation 

process after publication. 

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

Section, Executive 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 1 & 2 Customer Support 

40220 Tarnos – France 

Fax: +33 (0)5 59 74 45 15 

or contact your nearest technical representative at

www.turbomeca-support.com.