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/F100/11 Rear Spar & MLG Bottom Joint Fittings 4/99 Applicability: F.28 Mk.0100 aircraft, serial numbers, 11244 through 11390. Requirement: Replace affected fittings and reinforce the MLG spar fittings, the rear spar webs and the new bottom joint fittings in accordance with Fokker Service Bulletin (SB) F100- 57-020 dated 27 April 1992. Note: RLD BLA 92-075 refers. Compliance: Unless previously accomplished, before accumulating 13,500 flight cycles since new. This Airworthiness Directive becomes effective on 22 April 1999. Background: During fatigue testing of the F.28 Mk.0100, cracks were found in the main landing gear spar fitting at wing STA.2800 and in the rear spar web at STA.2900. This condition, if not corrected, will result in loss of structural integrity of the aircraft in the affected areas. This AD requires the replacement of the affected fittings and subsequent reinforcement.