AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section. Fokker F100 (F28 Mk 100) Series Aeroplanes AD/F100/69 Landing Gear Integrated Axle Nut and Spacer 9/2005 Applicability: Fokker Aircraft B.V. F28 Mark 0070 and Mark 0100 aircraft, all serial numbers equipped with Messier-Dowty (formerly known as Dowty Rotol and Dowty Aerospace Gloucester) Main Landing Gear (MLG) units. Requirement: 1. Replace each MLG wheel axle-nut and spacer with an integrated axle-nut/spacer assembly in accordance with the accomplishment instructions of Messier-Dowty SB F100-32-72 dated 25 January 1995 or later CAA (United Kingdom) approved revisions. 2. Amend the Aircraft Maintenance Manual (AMM) and Illustrated Parts Catalogue (IPC) in accordance with the instructions of Fokker Manual Change Notification - Maintenance (MCNM) F100-033 dated 30 April 1999. Note 1: Fokker 70/100 Service Letter (SL) 102 Revision 1 dated 12 February 1998; and Fokker Services SB F100-32-096 Revision 2 dated 29 April 2005 also pertain to this subject. Note 2: Civil Aviation Authority Netherlands Airworthiness Directive Nr NL-2005-008 refers. Compliance: 1. Within the next 12 calendar months after the effective date of this directive. 2. Prior to or at the same time as the replacement as required by Requirement 1 of this directive. This Airworthiness Directive becomes effective on 1 September 2005. Over the years, several Fokker 100 (F28 Mark 0100) operators reported that a MLG wheel fell off during regular operation of the aircraft. These incidents occurred due to a missing spacer, which had inadvertently not been installed during a previous wheel change. Omitting the installation of the wheel spacer allows the wheel to move sideways along the axle, which subsequently leads to bearing failure, followed by loss of the wheel. Investigation by Fokker and Messier-Dowty has shown that two separate items, the spacer and the axle nut, can be replaced by a single axle-nut/spacer assembly, to prevent the possibility of omitting the spacer. In 1995, Messier-Dowty issued Service Bulletin (SB) F100-32-72 to make sure that the operator does not assemble the axle nut without the spacer. Fokker subsequently issued SB F100-32-096 to notify Fokker 100 operators of the (optional) Messier-Dowty SB's existence. Background: At a later stage, Fokker revised the SB to the status of 'recommended". In spite of all this attention to the spacer problem, wheel losses are still being reported due to missing wheel nut spacers. This condition, if not corrected, may lead to further wheel loss incidents, each of which could conceivably result in loss of control of the aircraft during the take-off run, landing rollout or taxiing operations. Since a potentially unsafe condition has been identified that may exist or develop on aircraft of the same type design, this Airworthiness Directive requires the replacement of the axle-nut and spacer with an integrated axle-nut/spacer assembly. In addition, the AMM and IPC must be amended to prevent reversal to a separate axle- nut and spacer installation during a subsequent wheel change. David Villiers Delegate of the Civil Aviation Safety Authority 21 July 2005