COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Beagle B121 (Pup) Series Aeroplanes AD/BEA 121/17 Nosewheel Steering Mechanism 1/77 Applicability: All model B121 not incorporating Mod. No. BE314. Requirement: Action in accordance with Scottish Aviation SB No. B121/69. Compliance: Within 100 hours time in service after 31 January 1977 and thereafter at intervals not exceeding 100 hours time in service.