COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes AD/AC/50 Unfeathering Pump Supply Line - Replacement 8/73 Applicability: Model 690 with S/Nos. 11001 to 11063. Document: 1. Aero Commander SB No. 123A; or 2. FAA AD 73-13-9. Compliance: Within 100 hours' time in service after 31 August 1973.