COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pratt and Whitney Turbine Engines - JT9D Series AD/JT9D/12 Amdt 1 Fifteenth Stage Compressor Discs 9/89 Applicability: JT9D-3A, -7, -7A, -7H, -7AH, -7A(SP), -7F, -7J, -20, -20J. Requirement: Inspect 15th stage compressor discs P/N 658615 and 672915 in accordance with the requirements of PWA SB No.4908 Rev.1. Compliance: As detailed in the Requirement document. Background: This Directive has been amended to reflect the manufacturers latest revision to S.B. 4908. The revision, in part, reduces the initial inspection requirement from 6,500 cycles to 3,500 cycles.