COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F50 (F27 Mk 50) Series Aeroplanes AD/F50/58 Amdt 4 MLG Sliding Member Out-Stop Assembly 6/98 Applicability: All model F27 Mk 50 aircraft, all serial numbers, equipped with Dowty Aerospace MLG legs P/N 201017001, 201017002 and P/N 201020001 not incorporating Dowty Aerospace SB F50-32-27 R4. Requirement: 1. Inspect all main landing gear legs for correct installation in accordance with Part A of Messier Dowty SB F50-32-48 R4 dated June 21, 1995. Note: Fokker SB F50-32-025 dated September 23, 1992 also refers. 2. Inspect and measure the extension of each sliding member when the landing gear is fully extended in accordance with Part B of Messier Dowty SB F50-32-48 R4 dated June 21, 1995. 3. If while inspecting the MLG in accordance with Requirements (1) or (2) parts are found missing or damaged, action in accordance with Dowty Aerospace SB F50-32-27 R2 or SB F50-32-49, as applicable. Note: MLG legs previously modified in accordance with Dowty Aerospace SB F50- 32-27 R2 and R3 are exempt from the inspections of Requirement 1 and 2 . 4. Modify main landing gear leg in accordance with Dowty Aerospace SB F50-32-27 R4 dated December 18, 1992. Note: RLD AD 1996-159 (A) dated December 31, 1996, supersedes and cancels RLD AD 92-118/3 (A). Compliance: 1. Unless previously carried out, within 30 days from 27 March 1997. 2. Unless previously carried out, within 30 days from 27 March 1997. Thereafter reinspect at intervals not exceeding 500 flight cycles until requirement 4 has been complied with. 3. Before further flight. 4. Unless previously carried out, within 5000 flight cycles or 30 calendar months, whichever occurs first, after 27 March 1997. This Amendment becomes effective on 21 May 1998. Background: A report was received of an accident during landing in which an F50 aircraft left the runway sideways and was severely damaged. This event has been attributed to a MLG sliding member inadvertently overextending and allowing the torque links to move to an overcentre position, with the subsequent failure of the torque link centre joint pin. Amendment 1 was issued in response to a new RLD AD which advised that modification is now accepted as a terminating action for the current inspection. COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Amendment 2 was issued to reflect the latest issue of the Requirement Document which list the affected MLG serial numbers, and introduces an alternative terminating action for an inspection requirement. Amendment 3 was raised on receipt of RLD AD 1996-159 (A) dated December 31, 1996, which mandates terminating action. This amendment being raised to rectify Service Bulletin numbers referred to in Amendment 3. Amendment 3 of this Airworthiness Directive became effective on 27 March 1997 Amendment 2 of this Airworthiness Directive became effective on 31 March 1994. Amendment 1 of this Airworthiness Directive became effective on 4 April 1993. The original issue of this Airworthiness Directive became effective on 7 February 1993.