COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F100 (F28 Mk 100) Series Aeroplanes AD/F100/8 RH Wing Skin at Fuel Adaptor Position 4/99 Applicability: F.28 Mk.0100 aircraft, serial numbers 11244 through 11286, 11289 through 11293, 11295, 11297, 11300, 11303, 11306, 11308, 11310 and 11312. Requirement: Install internal and external doubler plates around the fuel adapter position in accordance with the Accomplishment Instructions of Fokker Service Bulletin (SB) F100-57-008 Revision 2, dated 22 September 1995. On aircraft that have already been modified in accordance with Fokker SB F100-57-008, Revision 1 (including changes as advised by the manufacturer), no further action is required. Note: RLD BLA 1991-131/3(A) refers. Compliance: Unless previously accomplished, before accumulating 12,000 flight cycles since new. This Airworthiness Directive becomes effective on 22 April 1999. Background: Fatigue tests on the F.28 Mk.0100 have shown that cracks may develop in the lower skin of the RH wing at the attachment bolt holes of the fuel adapter. This condition, if not corrected, reduces the fatigue life of the affected structure beyond acceptable limits. This AD requires a modification to prevent cracking.