COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES General Electric Turbine Engines - CT7 Series AD/CT7/5 Rotor Parts 5/94 Applicability: CT7-5A2,-7A and -9C turboprop engines; and CT7-2A and -6 turboshaft engines. Requirement: Action in accordance with GE Service bulletins: For CT7-5A2, -7A and -9C: SB A72-252 of 31 Aug 1990. For CT7-2A: SB A72-18 of 10 Sep1990. For CT7-6: SB A72-17 of 10 Sep 1990. Note: FAA AD 93-25-17 refers. Compliance: Before exceeding the `Max total allowable cycles' specified in the relevant Service Bulletins. Background: This AD requires the removal from service of certain gas generator rotor assembly parts that were plasma sprayed during manufacture . The requirement arises from results obtained during material testing which indicated that the plasma-spray process reduces the low cycle fatigue capability of the material.