Federal Register of Legislation - Australian Government

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AD/ARRIEL/27 Airworthiness Directives/Pt 106 — Engines as made
HP Turbine (Module M03) - Turbine Blade Displacement
Administered by: Infrastructure and Transport
Exempt from sunsetting by the Legislative Instruments Act 2003 s 54(2) item 9
Registered 15 May 2007
Tabling HistoryDate
Tabled HR21-May-2007
Tabled Senate12-Jun-2007
Date of repeal 23 Nov 2009
Repealed by AD/ARRIEL/27 - HP Turbine (Module M03) - Turbine Blade Displacement - CANCELLED



For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (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


HP Turbine (Module M03) - Turbine
Blade Displacement




ARRIEL 2B, 2B1, 2B1A turboshaft engines.

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


1.    Perform an inspection of the HP turbine in accordance with Mandatory Service Bulletin No. 292 72 2825 or later approved revisions.

2.    If the inspections detailed in Requirement 1 of this AD reveal HP blade rearward displacement, follow § 2.B of Mandatory Service Bulletin No. 292 72 2825 or later approved revisions  to determine which action has to be taken.  Depending on the blade rearward displacement result, the action will be either:

a.     Module 03 has to be removed,


b.    Inspect again.

Note 2:  The manufacturer requests the findings of the inspections detailed in this AD be forwarded to them within 7 days of the inspection being completed.

Note 3:  EASA AD 2007-0109 corr dated 20 April 2007 refers.


1.    Within 600 gas generator hours or 500 cycles, whichever come first of the previous HP turbine borescope inspection.  For Module 03 that have logged more than 600 hours or 500 cycles since new, repair or overhaul and for which the HP turbine borescope inspection was performed more than 600 hours or 500 cycles ago, this inspection must be performed within 100 hours upon effective date of this AD.

This inspection must be repeated within 600 gas generator hours or 500 cycles (whichever comes first), or sooner dependant upon the results of Requirement 2 of this AD.




2.    a.     Before further flight after the effective date of this AD.

b.    Within the schedules defined in Mandatory Service Bulletin No. 292 72 2825 § 2.B.


This Airworthiness Directive becomes effective on 7 June 2007.


Several cases of Gas Generator Turbine (HP Turbine) blade rearward displacement have been detected during borescope inspection or in the repair centre following engine disassembly.  Two of them resulted in blade rubs between the rear face of the fir-tree roots and the rear bearing support cover.  High HP blade rearward displacement can potentially result in blade release due to fatigue of the blade, which would cause an uncommanded in-flight engine shutdown.  On a single-engine helicopter, the result may be an emergency autorotation landing or, at worst, an accident.  The evaluation of this condition has prompted to require a periodic borescope inspection in order to detect HP blade rearward displacement.  Additionally, in case displacement is found above the specified limit, removal of Module 03 is required.  This precautionary measure has been taken only on engine powering single engine rotorcraft.

David Punshon
Delegate of the Civil Aviation Safety Authority

24 April 2007