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/F50/4 Fire Sensing Element (Fire Wire) Bonding 1/89 Applicability: All F27 MK 050 aircraft serial numbers 20103 to 20108, and 20110 to 20123 inclusive. Requirement: Action in accordance with Fokker SB F50-26-003. Note: Dutch AD BLA 88-46 also refers. Compliance: Prior to 26 February 1989. Background: Fokker have advised that undetected unserviceabilities of the fire sensing element (fire wire) can occur due to faulty bonding of the element.