EASA AD No.: 2013-0170

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EASA AIRWORTHINESS DIRECTIVE

AD No.: 2013-0170

Date: 30 July 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 2007-0044 dated 21 February 2007, including the 

Correction dated 27 February 2007.

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

Inspection / Replacement

Manufacturer(s): Turbomeca S.A.

Applicability: ARRIEL 2B, 2B1, 2B1A, 2B1B, 2C, 2C1, 2C2, 2S1 and 2S2 engines, all serial 

numbers.

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

AS 350 B3, EC 130 B4, AS 365 N3 and EC 155 B1, Changhe Z11 and Sikorsky 

S-76C helicopters.

Reason: In 2007, two cases of in-flight shutdown were reported on ARRIUS 2B1 engine, 

resulting from spline deterioration of the high/low pressure (HP/LP) fuel pump

assembly drive shaft. The Hydro-Mechanical Metering Unit (HMU) of the 

ARRIEL 2 engine has the same HP/LP pump drive design as the one installed 

on the ARRIUS 2B1 engine.

This condition, if not corrected, could lead to an uncommanded in-flight shutdown, which may result in an emergency autorotation landing.

To address this potential unsafe condition, Turbomeca published Mandatory 

Service Bulletin (MSB) 292 73 2812 for engines installed on single engine 

helicopters and a recommended Service Bulletin 292 73 2822 for engines 

installed on twin-engine helicopter. To mandate accomplishment of the actions 

as specified in Turbomeca MSB 292 73 2812, EASA issued AD 2007-0044, 

requiring a one-time inspection of the HMU drive gear shaft splines and 

coupling shaft assembly splines before exceeding a defined limit of operating 

hours, for single-engine applications.

Since that AD was issued, one case of wear of HMU drive gear shaft splines 
EASA AD No.: 2013-0170

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and coupling shaft assembly splines have been reported on both ARRIEL 2 

engines of the same helicopter. Based on this report, EASA reviewed this case 

again and decided that engines on twin-engine helicopters should also be 

inspected.

For the reasons described above, this AD retains and clarifies the requirements 

of EASA AD 2007-0044, which is superseded, and extends its applicability to 

ARRIEL 2C, 2C1, 2C2, 2S1 and 2S2 engines installed on twin-engine 

helicopters, and adding the ARRIEL 2B1B engine, which was recently certified. 

This AD requires inspections of each HMU and, depending on findings, 

replacement.

Effective Date: 13 August 2013

Required Action(s) 

and Compliance 

Time(s):

Required as indicated, unless accomplished previously:

(1) For ARRIEL 2B, 2B1, 2B1A and 2B1B within the compliance time specified 

in Table 1 of this AD, as applicable, inspect the HP pump drive gear shaft 

splines and coupling shaft assembly splines in accordance with the 

instructions of paragraph 2.B of Turbomeca MSB 292 73 2812 version G.

Table 1

Accumulated HMU 

operating hours on 

current module 01, on 

the effective date of this 

AD (see Note 1)

Compliance Time

500 and more

Within 25 HMU operating hours on 

current M01 after the effective date 

of this AD

Less than 500

Before exceeding 525 and not before 

500 accumulated HMU operating 

hours on current M01

(2) For ARRIEL 2C, 2C1, 2C2, 2S1 and 2S2 engines, within the compliance 

time specified in Table 2 of this AD, as applicable, inspect the HP pump 

drive gear shaft splines and coupling shaft assembly splines in accordance 

with the instructions of paragraph 2.B of Turbomeca MSB 292 73 2822 

version F. 

Table 2

Accumulated HMU 

operating hours on 

current module 01, 

on the effective 

date of this AD

(see Note 1)

Compliance Time

500 and more

or

not known

Within 200 HMU operating hours on current 

module 01 after the effective date of this 

AD

more than 300, but 

less than 500

Within 225 HMU operating hours on current 

module 01, but:

Before exceeding 700 operating hours, and

not before 500 operating hours

300 or less Between 500 and 525 accumulated HMU 

operating hours on current module 01 .
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Note 1: Accumulated HMU operating hours since HMU operates on current 

M01 (since first installation on current module 01). If the HMU was 

repaired/overhauled since first installation on current M01, operating hours 

since repair/overhaul must be considered.

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

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

serviceable HMU in accordance with the instructions of paragraph 2.B of 

Turbomeca MSB 292 73 2812 version G or MSB 292 73 2822 version F, 

as applicable.

(4) Inspections and corrective actions, accomplished before the effective date 

of this AD in accordance with the instructions of Turbomeca MSB 292 73 

2812 version F or earlier, or SB 292 73 2822 Update 2 or earlier, as 

applicable, are acceptable for compliance with the requirements of 

paragraph (1) or (2) or (3) this AD.

(5) Conditions for the installation of an HMU on a Module 01 or on an engine, 

from the effective date of this AD: Before the installation of an HMU, 

inspect and, depending on findings, correct the HP pump drive gear shaft 

splines and coupling shaft assembly splines in accordance with the 

instructions of paragraph 2.B of Turbomeca MSB 292 73 2812 version G, 

or MSB 292 73 2822 version F, as applicable.

An HMU that is new, or one that has not accumulated any operating hours 

since repair or overhaul, does not need to be inspected, prior to 

installation.

(6) Conditions for the installation of an engine on a helicopter, from the 

effective date of this AD: Installation of an engine on a helicopter is allowed 

provided that the HMU is in compliance with the requirements of this AD.

.Ref. Publications: Turbomeca MSB 292 73 2812 version G dated 24 June 2013.

Turbomeca MSB 292 73 2822 version F dated 21 June 2013.

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 03 July 2013 as PAD 13-093 for consultation until 

24 July 2013. No comments were received during the consultation period.

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:

Turbomeca 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).