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/F100/12 Main Wheel Assembly 4/99 Applicability: F.28 Mk.0100 aircraft, all serial numbers equipped with ABS Corporation Main Wheel Assembly P/N 5008142-4, Serial numbers APR91-0570 through FEB93-0965. Requirement: 1. Determine the Part number and Serial number of the Demountable Flange (inboard) Wheel Sub Assembly and the Demountable Flange (outboard) Wheel Sub Assembly. For the purposes of this AD, no further action against the Demountable Flange (inboard) Wheel sub assembly is required unless the sub assembly has a Part Number 5008142-4 and a serial number within the following ranges: APR91-0570 through OCT92-0858; or S-APR91-0097 through S-MAY92-0126. For the purposes of this AD, no further action against the Demountable Flange (outboard) Wheel sub assembly is required unless the sub assembly has a Part Number 5008140-1 and a serial number within the following ranges: APR91-0570 through FEB93-0965; or S-MAR91-0002 through S-FEB93-0100. Note 1: Spares of both sub assemblies are affected by the requirements of this AD. 2. For the inboard Wheel Sub Assemblies, inspect in accordance with Section II - Accomplishment Instructions, Paragraph C of ABS Corporation (ABSC) Service Bulletin SB Fo100-32-46 dated Dec 24, 1992. For the outboard Wheel Sub Assemblies , inspect in accordance with Section II - Accomplishment Instructions, Paragraph B of ABSC SB Fo100-32-48 dated Mar 10, 1993. If damage or cracks are discovered during the inspection on either the inboard or outboard Wheel sub assemblies, then replace the damaged assembly before further flight. Inboard/outboard Wheel sub assemblies affected by this AD may be used as suitable replacements, provided Requirement 3 of this AD has been completed prior to fitment. 3. Repair the inboard Wheel Sub Assembly in accordance with Section II - Accomplishment Instructions, Paragraph D of ABSC SB Fo100-32-46 dated Dec 24, 1992. Repair the outboard Wheel Sub Assembly in accordance with Section II - Accomplishment Instructions, Paragraph C of ABSC Fo100-32-48 dated Mar 10, 1993. COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Note 2: The repair of the Outboard Wheel sub assembly in accordance with the above constitutes terminating action for this AD. However, the applicable Component Maintenance Manual contains continuing inspection requirements. 4. Inspect the Inboard Wheel Sub Assembly in accordance with Section II - Accomplishment Instructions, Paragraphs B.1 and C of ABSC SB Fo100-32-46 dated Dec 24, 1992. Note 3: RLD BLA 93-009/3(A) refers. Note 4: Fokker Service Bulletins F100-32-070 and F100-32-073 refer. Compliance: 1. Within 3 months after the effective date of this AD. 2. For wheel assemblies with less than 800 flight cycles, inspect before 900 flight cycles, or within 200 flight cycles or at the next tyre chance, whichever occurs first. For wheel assemblies with greater than 800 flight cycles, inspect within the next 100 flight cycles or at next tyre change, whichever occurs first. In both cases, reinspect no later than every 500 flight cycles or at each tyre change, whichever occurs first. Continue to inspect until Requirement 3 of this AD becomes effective. 3. After the third inspection under Requirement 2 of this AD and before further flight after that inspection. 4. At the next two tyre changes after being repaired in accordance with Requirement 3 of this AD. Thereafter at every Wheel Assembly overhaul. This Airworthiness Directive becomes effective on 22 April 1999. Background: Several F.28 Mk.0100 operators reported finding cracks and broken spokes on Main Wheel Assemblies P/N 5008131-4. Investigation revealed that the manufacturer of the wheels, ABS Corporation, had discontinued a shot-peening procedure which was part of the manufacturing process before April 1991. As a result, a number of units were produced which are prone to fretting and cracking, due to the lack of shot- peening of the assembly mating surfaces and bolt bosses.