COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pratt and Whitney Canada Turbine Engines - PW100 Series AD/PW100/7 High Pressure Turbine Disc Replacement 3/94 DM Applicability: All PW100 series engines incorporating high pressure turbine discs, P/No. 3035711 or 3038411. Requirement: For PW100 series engines that incorporate high pressure turbine disc P/No 3035711 or 3038411, remove affected discs from service and replace with new or serviceable discs with less than 10,000 cycles since new (CSN) in accordance with the schedule detailed in Compliance below. Note: Transport Canada AD CF-94-01 also refers. Compliance: Effective 19 January 1994; Replace affected HPT discs as follows: Discs with 13,000 CSN or more, within the next 1,000 cycles but not to exceed 15,000 CSN. Discs with 12,000 CSN or more but less than 13,000 CSN, within the next 1,250 cycles but not to exceed 14,000 CSN. Discs with 10,000 CSN or more but less than 12,000 CSN, within the next 1,750 cycles but not to exceed 13,250 cycles. Discs with 8,000 CSN or more but less than 10,000 CSN, within the next 2,500 cycles but not to exceed 12,000 CSN. Discs with less than 8,000 CSN, not to exceed 10,000 CSN. All replacement discs with P/No. 3035711 or 3038411 installed per this AD must be retired from service before exceeding 10,000 CSN. Background: There have been two reported instances of high pressure turbine disc rim fractures which resulted from low cycle fatigue. One of these events was uncontained.