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 121/23 Engine Mounting Structure 10/79 Applicability: All Beagle B121 series 1 and 2, which have achieved 1000 hours time in service. Requirement: Action in accordance with British Aerospace (Scottish Division) SB No. B121/81. Compliance: Inspect within 50 hours time in service after 27 August 1979 and thereafter at intervals not exceeding 50 hours time in service. Background: The manufacturer reports that cases of engine mount cracking have been discovered in service.