COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fokker F27 Series Aeroplanes AD/F27/118 Forward Fuselage Skin Joint 6/89 DM Applicability: All models with S/Nos 10102, 10105 through 10684, 10686, 10687, and 10689 through 10692. Requirement: Inspect for fatigue cracks in the forward fuselage skin joints in accordance with Fokker Service Bulletin F27/53-108. Note: RLD BLA 89-020 refers. Compliance: Only aircraft that have flown more than a certain number of flights as at 10 April 1989 need to be inspected. This threshold number of flights is dependent upon the maximum cabin pressure differential for the aircraft. The threshold is 30,000 flights if the aircraft may have at any time operated at a cabin pressure differential of 5.5 psi, and 50,000 flights if the aircraft has always operated at a maximum cabin pressure differential of 4.16 psi. The compliance date for inspection is not later than 1 June 1989. Background: Fatigue test results and an in-service failure indicate that multiple site fatigue cracking can occur in the forward fuselage skin joints. The manufacturer is initially asking for a one time visual inspection of high time aircraft to determine the need for repetitive inspections. It is therefore important that all inspection results be forwarded to the Authority and to the manufacturer.