AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/F50/79 Amdt 3 and issues the following AD under subregulation 39.1 (1) of CAR 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 F50 (F27 Mk 050) Series Aeroplanes AD/F50/79 Amdt 4 Control Surfaces Leading Edge Attachment 11/2002 Applicability: Model F27 Mk 050, Mk 0502, and Mk 0604 aircraft, all serial numbers. Requirement: 1. Check the torque value of the elevator leading edge attachment screws and take corrective action, as necessary, in accordance with the Accomplishment Instructions of Fokker Service Bulletin (SB) F50-55-007 Revision 2, dated 17 June 2002. 2. Check the torque value of the rudder leading edge section attachment screws and take corrective action, as necessary, in accordance with the Accomplishment Instructions of Fokker SB F50-55-009 Revision 2, dated 17 June 2002. 3. Check the torque value of the aileron leading edge sections attachment screws and take corrective action, as necessary, in accordance with the Accomplishment Instructions of Fokker SB F50-57-020 Revision 2, dated 17 June 2002. 4. Modify the flight control surface leading edge section attachments by installing additional locking devices as follows: 1. for the rudder; in accordance with Fokker SB F50-55-010 Revision 2, dated 17 June 2002. b. for the ailerons; in accordance with Fokker SB F50-57-021 Revision 2, dated 17 June 2002. c. for the elevators; in accordance with Fokker SB F50-55-008 Revision 3, dated 17 June 2002. Note 1: Compliance with Requirement 4 constitutes terminating action for the actions required by Requirements 1, 2, and 3. Note 2: Netherlands CAA AD 2000-131/2 refers. Compliance: 1. Within the next 6 months after 31 October 2002 or at the expiry of the 12 calendar months interval as required by the previous issue of this Directive, whichever occurs first, and thereafter at intervals not to exceed 6 calendar months; until compliance with Requirement 4. 2. Within the next 12 months after 31 October 2002 or at the expiry of the 4,000 flight hours or 24 calendar months interval as required by the previous issue of this Directive, whichever occurs first, and thereafter at intervals not to exceed 12 calendar mont hs; until compliance with Requirement 4. 3. Within the next 6 months after 31 October 2002 or at the expiry of the 12 calendar months interval as required by the previous issue of this Directive, whichever occurs first, and thereafter at intervals not to exceed 6 calendar months; until compliance with Requirement 4. 4. Within the next 24 calendar months after 31 October 2002 or 15 years time- since-new of the aircraft, whichever occurs first. This Amendment becomes effective on 31 October 2002. Background: The RLD received an operator's report of an incident where, after landing, the elevator control was found to be binding in the fully "up" position. Subsequent investigation revealed that an attachment screw had come loose, moving out of the elevator leading edge section against the horizontal stabiliser. This condition could lead to further incidents of elevator binding, possibly resulting in loss of control. Amendment 1 expanded the AD inspection to include attachment screws of the rudder and aileron leading edges. Amendment 2 expanded the compliance requirements for the rudder leading edge attachment screws; as a result of a recent evaluation which concluded that the rudder is of less airworthiness concern than originally envisaged, and the requirement for rudder removal to accomplish the task. Amendment 3 required modification action by installing additional locking devices; which terminates the on- going repetitive check requirements. Amendment 4 is issued in response to a new issue of the related CAA-NL AD which reduces the intervals for inspection and re-tightening of the flight control surfaces leading edge attachment screws, as well as introduce a new limit for compliance with the required modification. The AD was prompted by an operator report of in- flight vibration and subsequent finding of a loose elevator leading edge section that had been inspected 7 months previously. Amendment 3 of this Airworthiness Directive became effective on 22 March 2001. Amendment 2 of this Airworthiness Directive became effective on 30 December 1999. Amendment 1 of this Airworthiness Directive became effective on 12 August 1999. The original issue of this Airworthiness Directive became effective on 10 September 1999. David Charles Punshon Delegate of the Civil Aviation Safety Authority 19 September 2002 The above AD is notified in the Commonwealth of Australia Gazette on 9 October 2002.