COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Gulfstream (Grumman American/ American Aviation) AA-1 Series Aeroplanes AD/AA-1/9 Rudder Control - Spring Replacement NK Applicability: All models. Document: American Aviation SB No. 131. Compliance: For aircraft with more than 1000 hours total time in service as at 25 July 1972 - within 50 hours' time in service after 25 July 1972 and thereafter at intervals not exceeding 1000 hours' time in service. For aircraft with less than 1000 hours total time in service - before achieving 1000 hours total time in service and thereafter at intervals not exceeding 1000 hours' time in service.