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/F50/15 Engine Air Intake Seal 5/89 DM Applicability: Model F27 mark 050 with serial numbers: 20103 through 20108 20110 through 20144 20146 and 20147 20150 through 20152 20155 through 20161 Requirement: Action in accordance with Fokker 50 Service Bulletin No. F50-30-004. Note: RLD AD BLA 89-32 refers. Compliance: Prior to 31 May 1989. Background: The manufacturer has determined that ice accumulating at the rear of the engine air intake and on the flexible seal, can shed into the engine and cause a momentary flame-out.