COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 737 Series Aeroplanes AD/B737/117 Main Cargo Door 6/98 Applicability: Model 737-200 and -300 series aircraft equipped with a main deck cargo door installed in accordance with Supplemental Type Certificate SA2969SO. Requirement: Perform a detailed visual inspection to detect cracks in the hinge and lift actuator box area of the main deck cargo door and upper jamb of the fuselage. Pay particular attention to the upper frame of the fuselage and upper jamb frames of the main deck cargo door, primary longeron, and clips of the fuselage, primarily in the hinge and lift actuator box area. If any crack is detected, replace the cracked part with a new part having the same part number. Note: FAA AD 98-04-41 Amdt 39-10352 refers. Compliance: Before 31 May 1998, and thereafter at intervals not to exceed 600 flight cycles. This airworthiness directive becomes effective on 21 May 1998. Background: The FAA received reports of cracks found during a heavy maintenance check; in the upper jamb area of the fuselage and in the main deck cargo door. Unchecked cracking could result in reduced structural integrity of the main cargo door and/or fuselage, and consequent loss or opening of the main deck cargo door while the aircraft is in flight.