Ad/CF6/62 - High Pressure Turbine Disc (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.

General Electric Turbine Engines - CF6 Series

AD/CF6/62 High Pressure Turbine Disc 11/2006

Applicability:

General Electric Company (GE) CF6-80 model turbine engines as specified in FAA AD 2006-16-06.

Requirement:

Action per the technical requirements of FAA AD 2006-16-06.

Note 1:  FAA AD 2006-16-06, Amdt 39-14706 refers.

Note 2:  This directive supersedes CASA AD/CF6/54 (FAA AD 2004-04-07).

Compliance:

As specified in the requirement document with an effective of 26 October 2006.

This Airworthiness Directive becomes effective on 26 October 2006.

Background:

The AD is superseding an existing airworthiness directive (AD) for GE CF6-80 series turbofan engines with certain stage 1 high- pressure turbine (HPT) rotor disks.  That AD currently requires an initial inspection as a qualification for the mandatory rework procedures for certain disks, and repetitive inspections only for certain disks for which the rework procedures were not required.  That action also requires reworking certain disks before further flight, and removes certain CF6-80E1 series disks from service.  This AD requires the same actions but shortens the compliance schedule for HPT disks that have not been previously inspected using AD/CF6/54 (FAA AD
2004-04-07), which this AD supersedes.  This AD results from a recent report of an uncontained failure of a stage 1 HPT disk.  The issuing of this AD is to detect and prevent cracks in the bottoms of the dovetail slots that could propagate to failure of the disk and cause an uncontained engine failure.

James Coyne
Delegate of the Civil Aviation Safety Authority

13 September 2006