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 CAR 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 - TFE 731 Series AD/TFE 731/32 Fan Rotor Disc 4/2002 Applicability: TFE731 -2, -3, and -4 series turbofan engines with fan rotor discs part numbers (P/N's) 3072162 -All, 3072816 -All, 3073436 -All, 3073539-All and 3074529 -All. (where All denotes all dash numbers). Requirement: Replace applicable fan rotor discs in accordance with Honeywell SB TFE731-A72- 3668. Note 1: FAA AD 2001-23-09 refers. Note 2: As of 31 December 2002 applicable fan rotor discs will be obsolete. As of that date, the requirements of AD/731/12, AD/731/19, AD/731/21, AD/731/27, AD/731/28, and AD/731/30 will be cancelled. Compliance: Effective 18 April 2002: 1. At next access to fan rotor disc; or 2. At next scheduled inspection of the fan rotor disc; or 3. Prior to 31 December 2002, whichever occurs earliest. Note 3: Access to the fan rotor disc is defined as whenever the fan shaft is unstretched. Note 4: Serviceable discs are those part numbers not listed in this Directive. This Airworthiness Directive becomes effective on the 18 April 2002. AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE 731 Series AD/TFE 731/32 (continued) Background: The fan rotor disc has had a history of problems relating to cracking in the dovetail area. Cracking can lead to failure of the disc causing an in-flight shutdown constituting a flight safety hazard. Currently inspection techniques using the eddy current process have identified this cracking. Experience is now showing that this process is not detecting all cracks, fan rotor discs that have the potential for failure must be removed from service. The applicable disc P/N's are listed in this Directive. Eugene Paul Holzapfel Delegate of the Civil Aviation Safety Authority 8 March 2002 The above AD is notified in the Commonwealth of Australia Gazette on 27 March 2002.