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/F100/19 Amdt 1 Horizontal Stabiliser Structure 6/99 Applicability: All F.28 Mk.0100 specified in Fokker Service Bulletin (SB) F100-55-021 Revision 2, except those aircraft which have already fully complied with Fokker SB F100-55-021 Revision 1. Requirement: 1. Unless modified per requirement 2a before 1000 flight cycles since new, inspect the horizontal stabiliser main hinge fitting Hi-lok bolt holes in accordance with Part 5 of the Accomplishment Instructions of Fokker SB F100-55-021 Revision 2. 2. Modify the horizontal stabiliser main hinge fittings and replace or modify, as applicable, the connecting angles at Rib 215 in accordance with either: 1. Part 3 or Part 4 of the accomplishment instructions of Fokker SB F100-55-021 Revision 2, for aircraft with less than 1000 flight cycles since new at time of modification, or; b. Part 6 or Part 7 of the accomplishment instructions of Fokker SB F100-55-021 Revision 2, for aircraft with 1000 flight cycles, or more, since new, or; c. Instructions issued by Fokker Aircraft Services for inspection, modification or repair where cracks indications during requirement 1 inspection are beyond the limits listed in Fokker SB F100-55-021 Revision 2. 3. Modify Rib 215 of the horizontal stabilizer either; 1. In accordance with Part 8 of the accomplishment instructions of Fokker SB F100-55-021 Revision 2, or; b. Instructions issued by Fokker Aircraft Services for inspection, modification or repair where cracks indications during requirement 1 inspection are beyond the limits listed in Fokker SB F100-55-021 Revision 2. Note: RLD BLA 93-137/2(A) refers. Compliance: 1. Inspect before accumulating 15,000 flight cycles since new or before 17 August 1999, whichever occurs later. 2. Unless already accomplished, before further flight following the inspection in accordance with Requirement 1. 3. Before further flight following the inspection in accordance with Requirement 1 or in conjunction with requirement 2 compliance. This Amendment becomes effective on 17 June 1999. COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Background: During fatigue tests on the F.28 Mk.0100 for the stabilisers, cracks were found in the flanges of the LH and RH main hinge fittings. If not corrected, these cracks may lead to a deteriorated fatigue life of the horizontal stabiliser main hinge fitting structure. This AD requires an inspection and modification to detect cracks at an early stage and to improve fatigue life. Amendment 1 is issued to update the service bulletin reference, as experience has resulted in revisions to the Accomplishment Instructions. Aircraft that have been modified in accordance with previous revision do not require further work. The initial issue of this Airworthiness Directive became effective on 22 April 1999.