March 13, 2026 — Washington, D.C. The U.S. Federal Aviation Administration (FAA) issued a Notice of Proposed Rulemaking (NPRM) for an Airworthiness Directive (AD) requiring inspections on certain Boeing 787-8, -9, and -10 aircraft due to manufacturing errors causing excessive “shim gaps” between fuselage sections and lower outboard wing skins. The issue, stemming from high preload forces on side-of-body (SOB) splice plates, could lead to undetected fatigue cracks in critical wing structures, Docket No. FAA-2026-2295; AD Project Identifier AD-2025-01361-T.
The NPRM, published in the Federal Register, affects 17 U.S.-registered 787s manufactured within a specific timeframe, as identified in Boeing Alert Requirements Bulletin B787-81205-SB570048 RB, Issue 001, dated August 11, 2025. Public comments are open until April 27, 2026.
Unsafe Condition and Inspections
“The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 787-8, 787-9, and 787-10 airplanes. This proposed AD was prompted by a Boeing investigation for manufacturing errors and excessive preload forces at the lower side of body (SOB) splice plates common to the lower outboard wing skins.”
The directive mandates repetitive ultrasonic (UT) and detailed visual (DET) inspections for cracks in splice plates, rear spar terminal fittings, lower chords, front spar terminal fittings, and jack pads, with repairs if cracks are found. Compliance follows the bulletin’s schedule.
Estimated costs total $413,270 for U.S. operators, or up to $24,310 per aircraft per inspection cycle (286 work-hours at $85/hour), excluding repair costs.
Background and Boeing’s Position
The shim gap issue originated at Boeing’s North Charleston plant and was flagged by a 2024 whistleblower. Despite Boeing’s full-scale fatigue tests simulating 165,000 cycles showing “zero findings in fatigue in our composite structure,” the FAA deemed existing inspections inadequate.
Boeing supports the mandate: “We support the FAA making that guidance mandatory. The 787 global fleet can continue normal operations. We identified the root cause of this issue and corrected it in production.”
FAA To Mandate Boeing 787 Inspections Following ‘Shim Gap’ Manufacturing Errors, as headlined by Simple Flying, echoes coverage from FlightGlobal on the proposal following Boeing’s August 2025 bulletin. Social media, including @VibewireCentral on X, highlighted the story.
The FAA NPRM addresses gaps in detection to ensure wing load-bearing capacity, with no fleet grounding required.