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/F50/39 Elevator Torque Tube Bearing Plate Bolts 2/91 DM Applicability: F27 Mark 050 aircraft with S/Nos 20103 through 20184. Requirement: Action in accordance with the technical requirements of Netherlands AD BLA 90-104. Note: Fokker SB F50-55-004 refers. Compliance: Prior to accumulating 500 hours time in service after revised date of 4 December 1990, or prior to revised date of 1 June 1991, whichever occurs first. Background: Country of origin AD. It was found that, during production, bolts were tightened to a torque load that was too high. To prevent failure, replacement of bolts is required.