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/F50/30 Fuselage Upper Girder Connection at Frame Sta. 3415 1/90 Applicability: F27 Mark 50, serial numbers 20103 through to 20108, and 20110 through to 20147. Requirement: Incorporate reinforcement modification in accordance with Fokker Service Bulletin F50-53-020 dated 15 September 1989. Note: RLD BLA 89-110 refers. Compliance: Prior to accumulating 10,000 flight cycles. Background: Full scale fatigue tests have determined that the connection angle between the upper girder of the flight compartment window and the upper torsion box of the passenger door has insufficient fatigue resistance. This AD introduces a reinforcement bracket to the area.