COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES AlliedSignal (Garrett/AiResearch) Turbine Engines - TPE 331 Series AD/TPE 331/25 Third Stage Turbine Wheel P/N 3101516/1 - Replacement 3/86 Applicability: TPE-331-10-501G models fitted with third stage turbine wheel P/N 3101516/1. Requirement: Remove the forged third stage turbine wheel, P/No. 3101516/1, and replace it with a cast third stage turbine wheel, P/No. 3102655/1; or AD/AIR-T/34. Compliance: Within 100 hours time in service after 11 June 1979.