COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Propellers - Variable Pitch - Dowty Rotol AD/PR/15 Blade Bearings - Overhaul Procedures NK Applicability: All models. Document: SB No. 61-380. Effective: 31 January 1974.