COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES AlliedSignal (Garrett/AiResearch) Turbine Engines - ATF3 Series AD/ATF3/4 High Pressure Turbine Disc Inspection 3/95 Applicability: AlliedSignal Model ATF3-6 and -6A engines as detailed in AlliedSignal Alert Service Bulletin No. ATF3-A72-6184 Revision 1. Requirement: Inspect the high pressure turbine (HPT) disc in accordance with AlliedSignal Alert Service Bulletin No. ATF3-A72-6184 Revision 1. Note: FAA Airworthiness Directive 94-23-04 refers. Compliance: Effective 2 March 1995: 1. Engines with 1550 or more HPT disc cycles since new, within 50 cycles. 2. Engines with less than 1550 HPT disc cycles since new, within 300 cycles or prior to accumulating 1600 cycles since new, whichever occurs first. Background: This Directive has been issued to require a once only inspection of the HPT disc curvic and bore area for cracks. The requirement follows reports of cracks being found in the subject discs during routine inspections.