COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Auxiliary Power Units AD/APU/12 Compressor Wheel 8/97 Applicability: Sundstrand Aerospace T-62T-40C series Auxiliary Power Units incorporating Compressor Wheel, P/No 162690-1, 165111-1 or 167200-1 Requirement: Replace affected compressor wheels in accordance with Sundstrand Aerospace Service Bulletin T-62T-49-120 Revision 2 dated 5 November 1996. Note: FAA AD 96-25-12 also refers. Compliance: As detailed in the requirement document. This airworthiness directive becomes effective on 17 July 1997. Background: The manufacturer has advised three compressor wheel failures have occurred as a result of fatigue cracks propagating from screw holes on the backface of the compressor wheel. Compressor wheel rupture could result in an uncontained APU failure and damage to an aircraft.