COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F27 Series Aeroplanes AD/F27/113 RH Elevator Stn 300 Rib 7/87 Applicability: All models listed in the Requirement Document. Requirement: Action in accordance with Fokker SB F27/55-63. Note: RLD BLA 87-32 refers. Compliance: Prior to 31 December 1987. Background: The manufacturer reports instances of heavy corrosion and stress corrosion cracking in the milled rib.