AD/Arriel/17 Amdt 1 Engine Gas Generator Second Stage Turbine (Cth)

AIRWORTHINESS DIRECTIVE

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/17 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/17 Amdt 1 Engine - Gas Generator
Second Stage Turbine 3/2006

Applicability:

ARRIEL 1B engines which have been modified per TU 148 and ARRIEL 1D, 1D1 and 1S1 engines.

Requirement:

1.    Carry out a check of the axial displacement of the 2^nd stage turbine blades and perform any subsequent rectification following the check in accordance with:

Turbomeca Service Bulletin (SB) A292 72 0807 for ARRIEL 1B engines,

SB A292 72 0809 for ARRIEL 1D and 1D1 engines,

SB A292 72 0810 for ARRIEL 1S1 engines

2.    For ARRIEL 1B engines, which have been modified per TU 148 and ARRIEL 1D and 1D1 engines  replace the 2^nd stage turbine in accordance with SB A292 72 0807 or SB A292 72 0809 as is applicable.

Note:  DGAC AD F-2004-047R1 EASA approval No. 2005-6374 dated 18 October 2005 refers.

Compliance:

For Requirement 1:

For all engines once the 2^nd stage turbine has accumulated 1,200 flight hours or 3,500 cycles since new or inspection in accordance with the requirement document:

ARRIEL 1B engines that have been modified per TU 148:

For 2^nd stage turbines that have not been checked or with more than 150 flight hours since the last check was performed in accordance with SB A292 72 0263, check within 50 flight hours. Thereafter carry out a check at intervals not to exceed 200 flight hours until fitment of a replacement turbine from Turbomeca.

For 2^nd stage turbines that have less than 150 flight hours since a check performed in accordance with SB A292 72 0263, check within 200 flight hours from the last check, thereafter carry out a check at intervals not to exceed 200 flight hours until fitment of a replacement turbine from Turbomeca.

ARRIEL 1D and 1D1 engines:

For 2^nd stage turbines that have not been checked or with more than 100 flight hours since the previous check was performed in accordance with SB A292 72 0263, check within 50 flight hours.Thereafter carry out a check at intervals not to exceed 150 flight hours until fitment of a replacement turbine from Turbomeca.

For 2^nd stage turbines that have less than 100 flight hours since a check performed in accordance with SB A292 72 0263, check within 150 flight hours from the previous check, thereafter carry out a check at intervals not to exceed 150 flight hours until fitment of a replacement turbine from Turbomeca.

ARRIEL 1S1 engines:

For 2^nd stage turbines that have not been checked or with more than 100 flight hours since the previous check was performed in accordance with SB A292 72 0263, check within 50 flight hours.Thereafter carry out a check at intervals not to exceed 150 flight hours until fitment of a replacement turbine from Turbomeca.

For 2^nd stage turbines that have less than 100 flight hours since a check performed in accordance with SB A292 72 0263, check within 150 flight hours from the previous check, thereafter carry out a check at intervals not to exceed 150 flight hours until fitment of a replacement turbine from Turbomeca.

For Requirement 2:

ARRIEL 1B engines which have been modified per TU 148:

If the 2^nd stage turbine blades have accumulated more than 2,200 flight hours since new or since last inspection in accordance with the requirement document, upon receipt of an inspected turbine from Turbomeca or by 31 August 2006, whichever occurs first.

For ARRIEL 1D and 1D1 engines:

If the 2^nd stage turbine blades have accumulated more than 1,500 flight hours since new or since last inspection in accordance with the requirement document, upon receipt of an inspected turbine from Turbomeca or by 31 August 2006, whichever occurs first.

This Amendment becomes effective on 16 March 2006.

Background:

Several cases of 2^nd stage turbine blade release have occurred in service that has resulted in uncommanded in-flight shut down.  This Directive requires inspection of the 2^nd stage turbine blades for axial displacement and the replacement of turbine where the displacement exceeds the allowable published limit.

This amendment clarifies the engine listed in the applicability section.  It also revises the requirements for 1D and 1D1 engines.  These engines are now grouped together and may require additional work to be carried out.

The original issue of this Airworthiness Directive became effective 8 July 2004.

James Coyne
Delegate of the Civil Aviation Safety Authority

1 February 2006