Federal Register of Legislation - Australian Government

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AD/ARRIEL/26 Amdt 1 Airworthiness Directives/Pt 106 — Engines as made
Engine Electronic Control Unit Software
Administered by: Infrastructure and Transport
Exempt from sunsetting by the Legislative Instruments Act 2003 s 54(2) item 9
Registered 16 Apr 2007
Tabling HistoryDate
Tabled HR08-May-2007
Tabled Senate09-May-2007
Date of repeal 14 Aug 2012
Repealed by CASA ADCX 017/12 - Revocation of Airworthiness Directives



On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/ARRIEL/26 and issues the following AD under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Turbomeca Turbine Engines - Arriel Series

AD/ARRIEL/26 Amdt 1

Engine Electronic Control Unit Software

6/2007 DM



Arriel 2B1 turboshaft engines, all serial numbers.


Note 1:  These engines are known to be installed on, but not limited to, Eurocopter
AS 350 B3 and EC 130 B4 single-engine helicopters.


Note 2:  This Amendment is not applicable to Arriel 2B engines; however as some incorrect engine model information may have been reported to CASA, the Amendment is distributed to  registered operators of both Arriel 2B and 2B1 engines.


Unless previously accomplished in accordance with the original issue of this Directive, either modify the engine electronic control unit (EECU) by downloading software version V5.02 (modification TU 144C), or replace the EECU with an EECU that has modification TU 144C incorporated.  Both actions are to be accomplished in accordance with Turbomeca Mandatory Service Bulletin 292 73 2144 dated 5 January 2007 or later approved revision.


Note 3:  EASA AD 2007-0085 refers.


No later than 31 August 2007.


This Amendment becomes effective on 18 April 2007.


Two cases of flame-out have been reported on Arriel 2B1 engines: one when lowering collective pitch on ground at landing and one when switching from Flight Position to Idle Position on ground.  Both flame-out events are explained as follows:


  • in case of stepper motor loss of steps to a value below the "level 1 failure" detection threshold, the fuel flow of the anti flame-out limit can be reduced,
  • the reduction can be sufficient to cause an engine flame-out when decreasing rapidly the demand for power (it can therefore also happen in flight).





This condition may lead to an uncommanded in-flight shut-down.  On a single-engine helicopter, the result may be an emergency autorotation landing or, at worst, an accident.  To prevent this, software version 5.02 (TU 144C) increases the anti flame-out limit in the event of small stepper motor loss of steps (below the "level 1 failure" detection threshold).


This Amendment is issued to more closely align with that issued by the European Aviation Safety Agency, deleting the requirement to accomplish the software upgrade at the next 100 hourly inspection.


The original issue of this Directive became effective on 5 April 2007.

David Punshon
Delegate of the Civil Aviation Safety Authority

12 April 2007