COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Pratt and Whitney Piston Engines AD/PW-P/15 Crankshaft Flyweight and Flyweight NK Liners - Inspection and Modification Applicability: R985 series. Document: Pratt & Whitney SB 1758 Rev. A. Compliance: Installed Engines - Before installation in an aircraft following each overhaul. Spare engines - Before installation in an aircraft after 2 November 1967 unless previously inspected and reworked or replaced as necessary in accordance with Pratt & Whitney SB No. 1758 or P&W Wasp Junior Overhaul Manual P/N 123440 at last overhaul.