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 787-8, 787-9, and 787-10 airplanes. The NPRM was published in the Federal Register on March 13, 2026 (91 FR 12312). The NPRM was prompted by a report indicating that a Boeing investigation for manufacturing errors and excessive preload forces at the lower SOB splice plates common to the lower outboard wing skins concluded that shim gaps may have exceeded engineering allowances. High pull up forces on the components may cause fatigue cracks to form at the fastener holes. In the NPRM, the FAA proposed to require, depending on configuration, UT inspections at certain splice plates, rear spar terminal fittings, lower chords, front spar terminal fittings, and jack pads for any cracks; repetitive DET of certain splice plates for any cracks; and applicable on-condition actions. The FAA is issuing this AD to address improper shim gaps that may lead to fatigue cracks. The unsafe condition, if not addressed, could result in undetected fatigue cracks that can grow to weaken primary wing structure until it cannot sustain limit load and result in subsequent loss of continued safe flight and landing.

Discussion of Final Airworthiness Directive

Comments

United Airlines commented that it had no objections to the proposed rule.

The FAA received additional comments from American Airlines (AAL) and The Foundation for Aviation Safety. The following presents those comments and the FAA's response.

Request for Simplified Compliance Time

AAL requested that the FAA revise the proposed AD to allow simplified compliance time tracking for the initial and repetitive inspections for all tasks, such as by allowing the use of only total flight hours (TFH)/total flight cycles (TFC) for the initial inspections and only flight hours (FH)/flight cycles (FC) for the repetitive inspections. AAL stated that the compliance times specified in Boeing Alert Requirements Bulletin B787-81205-SB570048-00 RB, Issue 001, dated August 11, 2025, require the use of an equation based on a combination of TFH and TFC to determine the initial inspection compliance time, and an equation based on the initial inspection and a combination of FH and FC to determine the repetitive inspection compliance times. AAL noted that the use of an equation for the initial and repetitive inspections places a burden on the airline as its internal tracking system does not support equation-based compliance times, therefore requiring either manual tracking of the required inspections for the life of the aircraft or choosing a conservative hours or cycles limit that the airline stated would greatly reduce the airplane yield between inspections.

The FAA disagrees with the request. The affected splice plates are flight-length sensitive. The equation-based compliance times account for the effects of both flight hours and flight cycles and are relieving in nature compared to compliance times based solely on TFH/TFC or FH/FC limits. Allowing the requested “simplified” compliance time tracking would therefore be more burdensome for operators, and many airplanes could become immediately out of compliance. The FAA has not changed this AD as a result of this comment.

Question on Holding Boeing Accountable for Manufacturing Quality Defects

The Foundation for Aviation Safety asked what the FAA is doing to hold Boeing accountable for ongoing manufacturing quality defects. The question did not request a change to this AD, and the FAA has not changed the AD as a result.

Revision to Material Citations

In the NPRM, the material citations inadvertently did not include “-00” as part of the bulletin number. The full citations are Boeing Alert Requirements Bulletin B787-81205-SB570048-00 RB, Issue 001, dated August 11, 2025; and Boeing Alert Service Bulletin B787-81205-SB570048-00, Issue 001, dated August 11, 2025. The FAA has revised this AD accordingly.

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 B787-81205-SB570048-00 RB, Issue 001, dated August 11, 2025. This material specifies procedures for performing repetitive UT inspections, depending on configuration, at splice plate No. 1 and No. 2, rear spar terminal fittings, lower chords, front spar terminal fittings, and jack pads for any cracks; repetitive DET of splice plates No. 1 and No. 2 for any cracks; and applicable on-condition actions. On-condition actions include 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 17 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD: ( printed page 55249)

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

The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators.

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: