COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES British Aerospace (Scottish Aviation) Twin Pioneer Series Aeroplanes AD/SA-TP/20 Drive Blocks on Dunlop Main Wheel NK Applicability: All models fitted with main wheels P/N AH50742, Issue 1 to 5. Document: Scottish Aviation TNS No. 31, Issue 3. Compliance: Forthwith.