COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F28 Series Aeroplanes AD/F28/21 Passenger Door - Locking Mechanism Modification NK Applicability: As detailed in the requirement document. Document: Fokker SB F28/52-43, Part IV. Compliance: Before 31 October 1974.