AD/TFE731/26 Amdt 1 Low Pressure Turbine First and Second Stage Disc Suspect Material Properties (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/TFE731/26 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.

AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series

AD/TFE731/26 Amdt 1 Low Pressure Turbine First and Second Stage Disc Suspect Material Properties 1/2010

Applicability:

AlliedSignal TFE731-3 series engines as detailed in AlliedSignal Alert Service Bulletin (ASB) No. TFE731-A72-3557.

Requirement:

Replace certain first and second stage low pressure turbine discs as listed by serial number in AlliedSignal Alert Service Bulletin (ASB) No. TFE731-A72-3557.

Note:  FAA AD 95-07-02 refers.

Compliance:

Unless already accomplished in accordance with the previous issue of this Directive, within 100 hours time-in-service (TIS) after the effective date of this Directive.

This Amendment becomes effective on 22 January 2010.

Background:

This Directive has been issued to require the removal from service of certain turbine discs suspected of having a material micro-structure with unacceptable crack growth properties.  This is both an engine in-flight shutdown and a disc containment concern.

This amendment references the applicable State of design Directive which is also applicable to AD/TFE731/24 Amdt 1.  For information, AD/TFE731/34 is also applicable to first and second stage low pressure turbine discs, but unrelated to this Directive.

Mike Higgins
Delegate of the Civil Aviation Safety Authority

4 January 2010