COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F27 Series Aeroplanes AD/F27/123 Flight Compartment Window Frames 10/91 Applicability: Serial numbers 10102, 10105 to 10684 inclusive, 10686, 10687, and 10689 to 10692 inclusive, which have been modified in accordance with Fokker Service Bulletin F27/21-30. Requirement: Inspect in accordance with the Technical Requirements of RLD AD 89-125, dated 13 October 1989. Note: Fokker Service Bulletin F27/53-109, dated 10 October 1989 refers. Compliance: (i) On aircraft serial numbers 10561 to 10684 inclusive, 10686, 10687, and 10689 to 10692 inclusive; upon accumulating 20 000 pressurisation cycles, or before 26 December 1991, whichever is the later, or (ii) On aircraft serial numbers 10102, and 10105 to 10560 inclusive: upon accumulating 30 000 pressurisation cycles, or before 26 December 1991, whichever is the later. Background: Full-scale fatigue tests on the similar F50 forward fuselage have indicated that cracks may occur in the F27 window post assemblies, particularly the side frames and frame corners. This AD calls for a one-time inspection. Incorporation of Repair Schemes I to V inclusive, in accordance with Fokker Service Bulletin F27/53-110, constitutes compliance with this AD.