COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pratt and Whitney Canada Turbine Engines - PT6A Series AD/PT6A/20 No. 2 Bearing Cover 10/85 Applicability: PT6A-6, -6A, -6B, -20, -20A, -20B, -6/C20 and PT6B-9 with S/Nos. prior to PC- E22659. Document: 1. Pratt & Whitney Aircraft of Canada SB No. 1188, Rev. 1; 2. Transport Canada AD No. CF-78-14; or 3. AD/UAC-T/32. Compliance: At next overhaul completed after 30 November 1978.