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 121/7 Amdt 1 Applicability: All models. Elevator Torque Tubes 2/92 Requirement: Action in accordance with mandatory British Aerospace SB B121/28 Revision 1. Compliance: As specified in the Requirement Document. Background: A severely corroded torque tube assembly has been found on an aircraft at a major inspection. SB has been revised and made mandatory by UK CAA.