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/F100/18 MLG Sliding Member Wheel Axle 4/99 Applicability: F.28 Mk.0100 aircraft, all serial numbers, if equipped with Dowty Main Landing Gear Part Number (P/N) 201072011, 201072012, 201072013, 201072014, 201072015, or 201072016. Requirement: Accomplish either one of the following: 1. Visually inspect the sliding members of all affected main landing gears installed on in-service aircraft for the presence of corrosion on the wheel axles in accordance with Fokker Service Bulletin (SB) F100-32-080, dated 4 October 1993, and in accordance with Dowty Aerospace SB F100-32-64, dated 23 September 1993; or, 2. Rework the axles in accordance with paragraph 2.B Part B of Dowty Aerospace SB F100-32-64 Revision 1 dated 18 February 1994; prior to, or at the same time of the rework of the axles, the main wheel brake units must be replaced in accordance with ABS Corporation SB Fo-100-57 Revision 1. Note 1: Aircraft that were on a sampling program (which expired on 1 January 1999) in conjunction with Requirement 2 actions in accordance with Fokker SF F100-32-083, are now required to introduce the Requirement 1 inspections. If corrosion is found during the Requirement 1 inspection, before further flight, rework the affected area and perform a Non-Destructive Testing (NDT) inspection for cracks in accordance with Appendix A of Dowty Aerospace SB F100-32-63 dated 29 July 1993, or in accordance with Appendix A of Dowty Aerospace SB F100-32-64 dated 23 September 1993. Note 2: The rework specified in the paragraph immediately above does not constitute terminating action for the Requirement 1 repetitive inspection requirement. If cracks are detected during any inspection required by this Directive, before further flight, replace the affected sliding member with a serviceable part in accordance with applicable maintenance procedures. Note 3: Replacement of the sliding member does not constitute terminating action for the repetitive inspection requirements of Requirement 1 of this Directive, unless the replacement part is in post Fokker SB F100-32-081 configuration. Note 4: RLD BLA 93-108/3(A) refers. Compliance: 1. Within three calendar months after the last inspection, or one calendar month after 22 April 1999, whichever occurs later; thereafter at intervals not to exceed three calendar months, until the requirements specified in the compliance note below are met. COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES 2. If Requirement 2 has been accomplished, introduce the Requirement 1 repetitive inspections within one calendar month after 22 April 1999, and thereafter at intervals not to exceed three calendar months until the requirements specified in the compliance note below are met. Note: After the replacement of main wheel brake units in accordance with ABS Corporation SB Fo100-32-57, Revision 1 dated 2 February 1994; and rework of the sliding member in accordance with paragraph 2.C PART C of Dowty Aerospace SB F100-32-64, Revision 1, the Requirement 1 repetitive inspections are no longer required. This Airworthiness Directive becomes effective on 22 April 1999. Background: An F.28 Mk.0100 operator reported the occurrence of an incident where, during push- back of the aircraft, a MLG wheel axle failed. Subsequent investigation revealed the presence of corrosion on most wheel axles in service with this operator. Preliminary results indicate that the crack which led to the failed axle had initiated from a corrosion pit located on the radius of the brake abutment flange on the axle.