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/F100/13 Rear Spar-to-Fuselage Attachment 4/99 Applicability: F.28 Mk.0100 aircraft, serial numbers, 11244 through 11319, 11321, and 11323 through 11332. Requirement: Reinforce the rear spar-to-fuselage attachment and cold-sleeve expand the rear spar end fitting fastener holes in accordance with Fokker Service Bulletin (SB) F100-53- 039 dated 10 February 1993. Note: RLD BLA 93-027(A) refers. Compliance: Unless previously accomplished, before accumulating 24,000 flight cycles since new. This Airworthiness Directive becomes effective on 22 April 1999. Background: During fatigue tests on the F.28 Mk.0100, cracks were found in the coupling plate and the web plate of the rear spar end fitting at the attachment to the frame at fuselage STA.17011. Further investigation revealed additional cracks around the fastener holes in the rear spar end fitting.