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EASA AIRWORTHINESS DIRECTIVE 

 AD No : 2007-0044 

Date: 21 February 2007

No person may operate an aircraft to which an Airworthiness Directive applies, except in accordance with the 

requirements of that Airworthiness Directive unless otherwise agreed with the Authority of the State of Registry.

Type Approval Holder’s Name : 

TURBOMECA 

Type/Model designation(s) : 

ARRIEL 2B Turboshaft engines 

TCDS Number: EASA.E.001 

Foreign AD: Not applicable 

Supersedure: DGAC France AD F-2005-188 (EASA Approval Number 2005-6408) 

ATA 73 

Engine Fuel and Control - Hydromechanical Metering Unit (HMU) - 

Visual Inspection of the Drive-Link Splines

Manufacturer(s): TURBOMECA 

Applicability: Arriel 2B, 2B1 and 2B1A turbo-shaft engines. These engines are known 

to be installed on, but not limited to, the following helicopters: Eurocopter 

AS 350 B3 and EC 130 B4 helicopters. 

Reason: The deterioration of the splines on the HP/LP pump assembly drive shaft 

may eventually interrupt fuel supply and cause uncommanded in-flight 

engine shutdown. The result may be an emergency autorotation landing 

or, at worst, an accident. 

Two cases of in-flight shutdown resulting from splines deterioration have 

been reported for the ARRIUS 2B1 engine, which has the same HP/LP 

pump drive design as the ARRIEL 2. These cases prompted us to 

require the inspection at 500 hours and each time the HMU is 

removed/installed. 

This AD modifies the content of the previous DGAC France AD F-2005-

188 (EASA Approval Number 2005-6408) in adding a one time 

inspection within 30 operating hours from effective date of this AD as 
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well as HMU re-installation according to a maintenance task modified to 

avoid this kind of wrong assembly. This has been set up following a one 

case of improper clipping of the coupling shaft onto the drive gear shaft, 

which resulted in an uncommanded in-flight engine shutdown (on a twin 

engine rotorcraft). This precaution measures has been taken only on 

engine powering single engine rotorcraft. 

Effective Date: 08 March 2007 

Compliance: 1. Visual inspection of HP pump drive gear shaft splines and coupling 

shaft assembly splines must be performed within 30 operating 

hours from effective date of this AD and not later than February 

28th 2007 (even if an inspection has already been performed in 

accordance with DGAC France AD F-2005-188 (EASA Approval 

Number 2005-6408). 

This inspection is not required for new engines equipped with their 

initial HMU, delivered by TURBOMECA, and whose HMU has not 

been removed since delivery.

2. In addition, further to this inspection:

y If the Hydromechanical Metering Unit (HMU) has logged 

more than 500 operating hours since new or since 

repair/overhaul inspect each time the HMU is 

removed/installed. 

y If the HMU has logged less than 500 operating hours since 

new or since repair/overhaul, perform the inspection as 

soon as the HP/LP pumps assembly has reached 500 

operating hours since new or since repair/overhaul, then 

each time the HMU is removed/installed.

3. If inspection reveals signs of wear, as listed in § 2.B.1.d of 

TURBOMECA Mandatory Service Bulletin No 292 73 2812, before 

next flight, replace HMU and coupling shaft assembly.

Ref. Publications: Turbomeca, S.A. Mandatory Service Bulletin No. 292 73 2812 - Update 

n°4 (or later approved revisions of this document)

Remarks : 1. If requested and appropriately substantiated the responsible EASA 

manager for the related product has the authority to accept Alternative 

Methods of Compliance (AMOCs) for this AD. 

2. This AD was posted as PAD 07-008 on 11 January 2007 for 

consultation until 12 February 2007. No comments were received 

during the consultation period. 

3. Enquiries regarding this Airworthiness Directive should be referred to 

the AD Focal Point - 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.