COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 737 Series Aeroplanes AD/B737/14 Forward Lower Cargo Doorway Frame 2/88 Applicability: All model 737 aircraft, Line Numbers 1 to 509 inclusive. Requirement: Inspect in accordance with Boeing SB 737-53-1051 (Revision 3 or later) until modified in accordance with the Preventative Modification contained in that SB. Note: FAA AD 86-09-06 refers. Compliance: As detailed in the Requirement Document. Background: There have been numerous reports of cracking in the fuselage frames which form the sides of the forward lower cargo doorway. Continued operation with undetected cracked frames could result in skin cracks and rapid decompression. This AD has been raised because SB 737-55-1051 has been listed in Section 9.0 of the 737 Supplemental Structural Inspection Document as having flight safety implications.