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/F100/6 Rib/Auxiliary Spar Attachment Rivets 4/99 Applicability: F.28 MK.0100 aircraft serial numbers, 11244 through 11256, 11259, 11260 and 11268 through 11278. Requirement: Replace affected aluminium alloy rivets with two nickel-copper alloy rivets and four hilok bolts in accordance with Fokker Service Bulletin (SB) F100-57-017 dated 12 September 1991. Note: RLD BLA 91-107 refers. Compliance: Unless previously accomplished, before accumulating 18,000 flight cycles since new or before 50 flight cycles after 22 April 1999, whichever occurs later. This Airworthiness Directive becomes effective on 22 April 1999. Background: During fatigue tests on the F.28 Mk.0100, six broken rivets were found. These rivets are located at the rib-to-auxiliary-spar attachment at wing STA.10110. This AD requires a modification to strengthen this attachment.