COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES AlliedSignal (Garrett/AiResearch) Turbine Engines - TFE731 Series AD/TFE731/14 First Stage L.P. Turbine Disc 9/88 TX Applicability: TFE 731-5 series engine with suspect first stage L.P. turbine disc whose serial numbers are identified in the Requirement document. Requirement: Remove from service affected first stage L.P. turbine discs in accordance with G.T.E.C. Alert SB TFE 731-A72-3371. Compliance: For discs with less than 750 operating cycles: Prior to exceeding 750 operating cycles. For discs with more than 750 operating cycles: Replace within 25 operating cycles after 27 June 1988. Background: This Directive is issued to reflect GTEC Alert SB TFE 731-A72-3371 which advises the recent in-flight shutdown caused by separation of 2 adjacent firtree posts and release of three turbine blades. Engineering investigation determined that discs had been manufactured from a suspect forging lot.