COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Propellers - Variable Pitch - Dowty Rotol AD/PR/24 Amdt 6 Beta Tube 2/90 Applicability: All models R354/4-123-F/13 R354/4-123-F/20 and R375/4-123-F/21. Requirement: Action in accordance with Dowty Rotol Mandatory Service Bulletin 61-A1021 Revision 10. Note: Swedish AD SAD No 1-007 refers. Compliance: In accordance with the Requirement document. Background: The manufacturer has further increased the service life of specific part number beta tubes and added additional propeller models to the applicability lists.