Airworthiness Directives; The Boeing Company Airplanes

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain The Boeing Company Model 737-300, -400, and -800 series airplanes. The NPRM published in the Federal Register on June 24, 2024 (89 FR 52408). The NPRM was prompted by a report that the protective spiral wrap used on certain galley wire bundles does not have the correct flammability properties and may not self-extinguish. In the NPRM, the FAA proposed to require inspecting certain galleys to determine part numbers, inspecting for an existing galley modification placard and marking on galleys with affected part numbers, and replacing wire bundle spiral wrap sleeving as applicable; and to prohibit the installation of affected parts. The FAA is issuing this AD to address the incorrect flammability properties, which, if not addressed, could result in electrical arcing or sparking, ignition of the spiral wire wrapping, and smoke and/or fire in the flight compartment, leading to loss of continued safe flight and landing.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from the Air Line Pilots Association, who supported the NPRM without change.

The FAA received additional comments from Aviation Partners Boeing. The following presents the comments received on the NPRM and the FAA's response to each comment.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that the installation of winglets per Supplemental Type Certificate (STC) ST00830SE and STC ST01219SE does not affect the accomplishment of the manufacturer's service instructions.

The FAA agrees with the commenter that STC ST00830SE and STC ST01219SE do not affect the accomplishment of the manufacturer's service instructions. Therefore, the installation of STC ST00830SE and STC ST01219SE does not affect the ability to accomplish the actions required by this AD. The FAA has not changed this AD in this regard.

Conclusion

The FAA reviewed the relevant data, considered any comments received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.

Material Incorporated by Reference Under 1 CFR Part 51

The FAA reviewed Boeing Alert Requirements Bulletin 737-25A1873 RB, dated August 25, 2023; and Boeing Alert Requirements Bulletin 737-25A1876 RB, dated September 1, 2023. This material specifies procedures for an inspection or records check to determine the part number of certain galleys; and for any galley with an affected part number found, an inspection for an existing galley modification placard and any marking indicating the galley was modified using certain service information; and, if applicable, replacement of wire bundle polyethylene protective spiral wrap protective sleeving with Boeing Material Specification (BMS) 13-81 wire protective sleeving. These documents are distinct since they apply to different airplane models.

This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

Costs of Compliance

The FAA estimates that this AD affects 4 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: