AD/CF6/56 - HP Stage 1 Turbine Discs (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Safety Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

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 39.1 (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.

General Electric Turbine Engines - CF6 Series

AD/CF6/56 HP Stage 1 Turbine Discs 7/2004

Applicability: General Electric CF6-80C2A5F, CF6-80C2B5F, CF6-80C2B7F and CF6-80C2D1F turbofan engines with high pressure turbine (HPT) stage 1 discs, part number (P/Ns) 1531M84G10 or 1531M84G12 installed.

Requirement: 1. Replace HPT stage 1 discs, P/N 1531M84G10 and 1531M84G12.

2. Do not install HPT stage 1 discs, P/N 1531M84G10 and 1531M84G12.

Note: FAA AD 2004-07-13 Amdt 39-13557 refers.

Compliance: For Requirement 1: At or before the disc accumulates 10,720 cycles since new (CSN).

For Requirement 2: That have exceeded 10,720 CSN.

This Airworthiness Directive becomes effective on 8 July 2004.

Background: This Directive is prompted by an updated low-cycle-fatigue (LCF) analysis of the HPT stage 1 disc. The action specified in this Directive are intended to prevent LCF cracking 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.