COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Boeing 737 Series Aeroplanes AD/B737/89 Main Deck Cargo Door - Existing Frame to Lower Sill Tie-Down 8/95 Applicability: All B737-200, -300 equipped with a main deck cargo door installed in accordance with Pemco Supplemental Type Certificate SA969SO. Requirement: Do a close visual inspection for cracking of the fuselage frames below the lower jamb sill between stringers 20L and 21L at fuselage stations 380, 400, 420, 440, 460 and 480. Note: FAA AD 95-06-05 and Pemco Alert Service Letter (ASL)737-53-0004 refer. Compliance: Initially inspect within 50 flights after 20 July 1995. Re-inspect at intervals not to exceed 450 flights until repaired in accordance with either of the schemes described in Pemco ASL 737-53-0004, Appendix I or II. Background: Two operators have reported finding cracks in the upper ends of the Boeing installed frames which are fastened to the lower jamb structure. Cracking of these frames could result in loss of the cargo door.