AD/Tay/15 High Pressure Turbine Stage 1 Discs (Cth)

AIRWORTHINESS DIRECTIVE

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.

Rolls Royce Turbine Engines - Tay Series

AD/TAY/15 High Pressure Turbine Stage 1 Discs 10/2005

Applicability:

Rolls Royce TAY 650-15 and TAY 651-54 engines.

Requirement:

1.    For Tay 650-15 engines: Re-establish the cyclic life limit for the high pressure turbine (HPT)  stage 1 disc fitted to Tay 650-15 engines that have previously been exposed to flight profiles that are different to the currently operated profile detailed in Rolls-Royce Deutschland Alert Service Bulletin (ASB)
TAY-72-A1676 dated 18 July 18 2005.  Calculate the life limit using the referenced ASB.

2.    For Tay 650-15 and Tay 651-54 engines no HPT stage 1 disc is permitted to have a cyclic life in excess of the cyclic life limits as defined in Rolls-Royce Deutschland ASB TAY-72-A1676.

Note:  LBA AD D-2005-252 EASA approval No. 2005-6100 dated 18 July 2005 refers.

Compliance:

1.    No later than 30 calendar days after the effective date of this Directive.

2.    In accordance with the Rolls-Royce Deutschland Alert Service Bulletin
TAY-72-A1676.

This Airworthiness Directive becomes effective on 29 September 2005.

Background:

This Directive requires replacing certain HPT stage 1 discs at or before reaching a new reduced life cycle limit.  This Directive is prompted by an updated low-cycle-fatigue (LCF) analysis of the HPT stage I disc performed by the manufacturer.  This Directive is intended to prevent LCF cracking and failure of the HPT stage 1 disc due to exceeding the life limit, which could result in an uncontained engine failure and damage to the aeroplane.

James Coyne
Delegate of the Civil Aviation Safety Authority

18 August 2005