AD/CF6/69 Fan Disk Coating (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/CF6/69 Fan Disk Coating 3/2008

Applicability:

GE CF6-80C2B1 turbofan engine, serial number (S/N) 690203, with fan disk, part number (P/N) 1703M78P11, S/N RPMDA662, installed.

Note 1:  This engine is installed on, but not limited to, a Boeing 747-300 aeroplane.

Requirement:

1.    Strip the Copper-Nickel-Indium (Cu-Ni-In) thermal coating from the pressure faces and slot bottoms of the stage 1 fan disk, and perform a microstructure evaluation. Use 3.A.(2)(a) through 3.A.(2)(b) of GE Service Bulletin (SB) No. CF6-80C2 S/B 72-1121, dated 23 January 2004, to strip the thermal coating and perform the microstructure evaluation.

2.    Ultrasonic inspect, fluorescent penetrant inspect, and eddy current inspect stage 1 fan disk. Use 3.A.(2)(c) of GE SB No. CF6- 80C2 S/B 72-1121, to inspect the disk.

3.    Apply Cu-Ni-In thermal coating to the pressure faces and slot bottoms of the stage 1 fan disks, using 3.A.(2)(d) of GE SB No. CF6-80C2 S/B 72-1121.

Later revisions of the above SB(s), approved by the United States Federal Aviation Administration (FAA) as an Alternate Method of Compliance (AMOC) to FAA AD 2007-24-07, are considered acceptable for compliance with the equivalent Requirements of this AD.

Note 2:  FAA AD 2007-24-07 Amdt 39-15273 dated 15 November 2007 refers.

Compliance:

Within 3,500 cycles-since-last Cu-Ni-In thermal spray coating of the dovetail slots, but no later than 30 June 2008, unless previously accomplished.

This Airworthiness Directive becomes effective on 13 March 2008.

Background: This AD results from a report that a repair shop did not meet the process requirements when applying Cu-Ni-In thermal coating to certain stage 1 fan disks.  The actions detailed in this AD are to prevent possible uncontained release of multiple fan blades, resulting in damage to the aeroplane.

Charles Lenarcic
Delegate of the Civil Aviation Safety Authority

21 January 2008