COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F50 (F27 Mk 50) Series Aeroplanes AD/F50/51 Auto Feather Control Unit 2/92 Applicability: All F50 aircraft. Requirement: Action in accordance with the technical requirements of Netherlands AD BLA 91-134 dated 22 November 1991. Note: Fokker SB F50-61-011 and Pratt and Whitney Canada SB No 21046 refers. Compliance: By 30 September 1992. Background: A number of inadvertent auto feather incidents have been reported.