FAA proposes inspections for Boeing 787 center wing sealant

The Federal Aviation Administration on Feb. 24 published a Notice of Proposed Rulemaking in the Federal Register (Docket No. FAA-2026-1322; Project Identifier AD-2025-01665-T) that would require detailed inspections and adhesion testing of sealant installations inside the center wing fuel tank on certain Boeing 787-8, 787-9 and 787-10 airplanes. The agency said the action was prompted by a production report that some sealant installations "did not receive required visual and adhesion inspections."

The proposed airworthiness directive would force operators to perform a detailed inspection of sealant in the left, right and center wing side-of-body areas, conduct an adhesion test of the sealant, and carry out applicable on-condition corrective actions where defects are found. The FAA warned of a direct safety risk: "The unsafe condition, if not addressed, could result in development of an ignition source within the fuel tank volume and a risk of a fuel tank explosion during a lightning strike event."

Comments on the NPRM must be filed by April 10, 2026. The FAA asked submitters to "Include 'Docket No. FAA-2026-1322; Project Identifier AD-2025-01665-T' at the beginning of your comments" and advised that "the most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data." The proposal text lists compliance intervals and the precise on-condition repair steps; the Federal Register entry and docket contain the full inspection procedures and any referenced service information.

The sealant NPRM arrives amid heightened FAA scrutiny of separate 787 systems. A final AD published in January and effective Feb. 20, 2026 (AD 2026-01-06; Docket FAA-2025-1110) requires high frequency eddy current or handheld X-ray fluorescence spectrometer inspections of cargo barrier fitting links after supplier notices suggested some links may have been manufactured from an incorrect titanium alloy. In November 2025 the agency opened another docket (FAA-2025-3426; Project Identifier AD-2025-00342-T) proposing replacement of certain mode control panels following reports of uncommanded altitude changes; that docket references 165 affected 787s and contains differing estimates of labor and total per-aircraft cost in agency filings.

Regulatory filings do not yet specify the total number of in-service airplanes directly affected by the new sealant rule or the aggregate cost to operators; the FAA's docket and regulatory evaluation for the NPRM will include those figures. Operators will be watching the compliance windows and test methods in the final rule because adhesion testing and any resulting repairs can require access to fuel-tank areas and may take aircraft out of service temporarily while work is completed.

The FAA said it will consider all comments received by the closing date and may amend the proposal in light of feedback. If adopted as a final AD, the rule would become mandatory for the airplanes and operators specified in the docket and would join a string of recent actions addressing disparate 787 production and component issues.