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/F50/48 RH Nacelle Aft Cone Fairing Fork-End Assemblies 10/91 Applicability: Serial numbers 20150, 20156, 20161, 20164, 20166, 20167, 20170, 20174 and 20175. Requirement: Action in accordance with the Technical Requirements of RLD AD 90-037, dated 12 April 1990. Note: Fokker Service Bulletin F50-54-007, dated 28 March 1990 refers. Compliance: Prior to exceeding 6000 flight cycles. Background: The fork-end fittings that attach the RH nacelle aft cone fairing to the nacelle on aircraft equipped with an APU, have been found to have insufficient fatigue lives. This AD requires replacement of the fork-end fittings, with improved units.