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/25 Main Fuel Tank Vent Pipes NK Applicability: All models. Document: Scottish Aviation TNS No. 47. Compliance: Modify forthwith. Inspect whenever the mainplane is assembled to the centre section.