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 737-8, 737-9, and 737-8200 airplanes. The NPRM was published in the Federal Register on November 25, 2025 (90 FR 53245). The NPRM was prompted by reports of cracks in the bear strap at the forward upper corner of the forward galley door cutout. In the NPRM, the FAA proposed to require an inspection of the fuselage skin for existing repairs and applicable on-condition actions. The FAA is issuing this AD to address cracks in the fuselage skin and bear strap, which may lead to the inability of the principal structural element to sustain limit loads and adversely affect the structural integrity of the airplane.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from The Boeing Company who supported the NPRM without change.

The FAA received additional comments from two commenters, including The Foundation for Aviation Safety and United Airlines (United). The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Explain How the Root Cause Is Addressed

The Foundation for Aviation Safety asked what the FAA and Boeing are doing to address the root cause of the defect. The commenter also asked if a structural defect is important enough to immediately ground an airplane after it is detected, why is the inspection for defects not accomplished long before the proposed compliance time.

The FAA is issuing this AD to address the unsafe condition on in-service airplanes. The required compliance times for the initial inspection and on-condition repetitive inspections and repair were established to ensure any crack is detected and repaired before the crack reaches critical length with multiple opportunities for detection. The rulemaking timeline was based on Boeing 737 fleet findings, supporting analysis, and the severity of the effect on the airplane ( i.e., safety consequences) if cracking propagates beyond a critical length. The FAA determined that the required actions and compliance times provide an acceptable level of safety. In addition, Boeing is introducing changes to the manufacturing process that address the root cause of the unsafe condition on in-production airplanes.

Request To Clarify Whether Certain Repairs Apply to Condition 1

United stated that Table 1, Condition 1 of the Accomplishment Instructions of Boeing Alert Requirements Bulletin 737-53A1408 RB, dated December 20, 2024, specifies to contact Boeing for alternative inspection instructions for any repair found during the general visual inspection of the fuselage skin. The commenter noted that Boeing Alert Service Bulletin 737-53A1408, dated December 20, 2024, does not provide guidance for repairs accomplished per the structural repair manual (SRM) limits in 737-8 and 737-9 SRM 53-00-01, for fuselage skin blend out and bear strap blend out repair. United requested clarification on whether repairs performed within allowable damage limits should be considered “repairs found” for the purposes of Table 1, or if such repairs may be treated as unrepaired areas, “no repair found.”

The FAA notes that Condition 1 applies to any repair, which includes blend out repairs accomplished per the SRM within the allowable damage limits. Such blend out repairs need to be evaluated to determine whether the repetitive inspection interval specified in the service information provides an acceptable level of safety for those repairs. Depending on findings, it may be necessary to reduce the inspection interval. The FAA has not changed this AD in response to this comment.

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, and any other changes described previously, 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 737-53A1408 RB, dated December 20, 2024. This material specifies procedures for an external general visual inspection of the fuselage skin for any repair and applicable on-condition actions. On-condition actions include repetitive detailed inspection for cracking of the fuselage skin; repetitive external surface high frequency eddy current (HFEC) inspections of the fuselage skin at certain fastener locations and the fuselage skin and bear strap along the edge of door corner radius for cracking; repetitive external subsurface low frequency eddy current (LFEC) inspection of the bear strap at certain fastener locations for cracking; and obtaining instructions from Boeing for alternative inspections or for crack repair.

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 471 airplanes of U.S. registry. ( printed page 50700) The FAA estimates the following costs to comply with this AD:

The FAA has received no definitive data on which to base the cost estimates for the on-condition repairs or for the alternative inspections specified in this AD.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.

The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that this AD:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Will not affect intrastate aviation in Alaska, and

(3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

The Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: