EASA AD No.: 2013-0079

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EASA AIRWORTHINESS DIRECTIVE

AD No.: 2013-0079

Date: 22 March 2013

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 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].

Design Approval Holder’s Name:

TURBOMECA

Type/Model designation(s):

ARRIEL 2 engines

TCDS Number: EASA E.001

Foreign AD: Not applicable

Supersedure: This AD supersedes EASA AD 2012-0141 dated 31 July 2012.

ATA 73 Engine Fuel & Control – Hydro-Mechanical Metering Unit –

Replacement

Manufacturer(s): Turboméca S.A.

Applicability: ARRIEL 2D engines, all serial numbers.

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

AS 350 B3 and EC 130 T2 helicopters.

Reason: During an ARRIEL 2D endurance test, the illumination of the Low Fuel 

Pressure warning light was observed. The investigation of the High Pressure / 

Low Pressure (HP/LP) pump assembly within the Hydro-Mechanical Metering 

Unit (HMU), removed following this occurrence, revealed a deterioration and a 

loss of the LP pump drive function.

This condition, if not corrected, could lead to the illumination of the Low Fuel 

Pressure warning light in flight, possibly resulting in an uncommanded in-flight 

shut-down (if the booster pumps are not switched on or under high load factor 

manoeuvres). For a single-engine helicopter, it may result in an emergency 

autorotation landing.

To address this potential unsafe condition, EASA issued AD 2012-0141 to 

reduce the service life of the HMU, requiring replacement before exceeding a 

defined limit of operating hours.

Since that AD was issued, further cases of deterioration of HMU rotating 

components have been reported, which occurred before the replacement 

interval required by that AD.

Prompted by these findings, Turboméca revised Mandatory Service Bulletin

(MSB) A292 73 2847, providing additional instructions for an inspection of the 
EASA AD No.: 2013-0079

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HMU, to be accomplished prior to rotating parts replacement.

For the reasons described above, this AD retains the requirements of EASA AD 

2011-0141, which is superseded, and requires inspection of the HMU and, 

depending on discrepancies, replacement with serviceable parts and 

replacement of the HMU rotating components before exceeding newly defined 

limits of operating hours.

Effective Date: 05 April 2013

Required Action(s) 

and Compliance 

Time(s):

Required as indicated, unless accomplished previously:

(1) Before exceeding 400 HMU operating hours since new, or since 

replacement of LP and HP fuel pumps rotating components in accordance 

with the instructions of Turboméca MSB A292 73 2847, whichever occurs 

later, and, thereafter, at intervals not to exceed 400 HMU operating hours, 

accomplish the following actions concurrently in accordance with the 

instructions of paragraph 2.B.(1) of Turboméca MSB A292 73 2847 version 

B:

- Inspect and replace the HMU inter-pump complete sleeve (female 

splines); and

- Inspect the HMU HP Pump and LP Pump male splines.

Note 1: a maximum of 25-hour tolerance can be applied to the defined 

inspection interval.

(2) If, during any inspection as required by paragraph (1) of this AD, a 

discrepancy is detected, before next flight, replace the affected HMU with a 

serviceable HMU in accordance with paragraph 2.B.(1) of Turboméca MSB 

A292 73 2847 version B.

Note 2: For the purpose of this AD, a serviceable HMU is an HMU that has 

accumulated less than 800 operating hours since new, or since replacement of 

LP and HP fuel pumps rotating components in accordance with the instructions

of Turboméca MSB A292 73 2847, and has accumulated less than 400 

operating hours since new or since the last inspection of the rotating 

components in accordance with the instructions of Turboméca MSB A292 73 

2847 version B.

(3) Before exceeding 800 HMU operating hours since new, or since 

replacement of LP and HP fuel pumps rotating components in accordance 

with the instructions of Turboméca MSB A292 73 2847, whichever occurs 

later, and, thereafter, at intervals not to exceed 800 HMU operating hours, 

replace the rotating components of the HP and LP Pumps including the 

complete sleeve, or replace the HMU with a serviceable HMU, in 

accordance with the instructions of paragraph 2.B.(1) of Turboméca MSB 

A292 73 2847 version B.

(4) Replacement of parts, accomplished before the effective date of this AD in 

accordance with the instructions of Turboméca MSB A292 73 2847 version 

A is acceptable to comply with the initial replacement as required by 

paragraph (3) of this AD.

(5) From the effective date of this AD, do not install an HMU on an engine, or 

an engine on a helicopter, unless in compliance with the requirements of 

this AD.

Ref. Publications: Turboméca MSB A292 73 2847 version B dated 06 March 2013.

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.
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2. Based on the required actions and the compliance time, EASA have 

decided to issue a Final AD with Request for Comments, postponing the 

public consultation process until 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 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).