Southwest Airlines

NPRM Requirement: Paragraph (g) states that “If any cracking is found, before further flight, modify the inboard MLG door hinge fittings on both left- and right-side inboard MLG doors, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-52A1167, dated December 1, 2011.” SWA Questions/Comments: SWA is concerned that paragraph (g) is worded to necessitate modification to either a left- or right-side MLG door where no crack was found. If a crack is found the door should be modified as per Boeing Alert Service Bulletin 737-52A1167 Figure 3 or Figure 4. However, if no crack is found on the opposite door, the repeat inspections could be maintained and no modification required before further flight. In addition, per the Boeing CDL one or both Inner MLG Doors may be removed. Therefore if a crack is found on one inner door hinge fitting, that door could be removed and placed on CDL until a serviceable pre- or post-modification door can be installed. If no crack is found on the opposite door, that door could remain in place, continue to be inspected, and modified at a convenient maintenance check. SWA Proposed Solutions: Reword paragraph (g) to state: “If any crack is found, before further flight, modify the cracked inboard MLG door hinge fitting in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-52A1167, dated December 1, 2011, or remove the cracked door per FAA approved Configuration Deviation List.”