FAA orders wing inspections on 77 Boeing 787s after shim-gap findings

The US Federal Aviation Administration issued a final airworthiness directive on 26 August requiring inspections of certain Boeing 787-8, 787-9 and 787-10 aircraft for fatigue cracks at the wing-to-body join. The rule follows a Boeing inquiry into manufacturing errors and high preload at the lower side-of-body splice plates that sit against the lower outboard wing skins.

Boeing concluded that shim gaps may have exceeded engineering limits. High pull-up forces on those parts can start fatigue cracks at fastener holes. If the cracks grow, the FAA said, they can weaken primary wing structure until it cannot take limit load, which would threaten continued safe flight and landing.

The directive covers 17 787s on the US register and 77 worldwide. Boeing has delivered more than 1,100 Dreamliners. Operators must run repetitive ultrasonic inspections, depending on configuration, at splice plates No. 1 and No. 2, rear spar terminal fittings, lower chords, front spar terminal fittings and jack pads. Some splice plates also need repetitive detailed visual checks. Cracks trigger Boeing’s on-condition repairs.

The FAA first proposed the rule in March 2026. The final version takes effect 35 days after publication in the Federal Register. Inspection-cycle cost is put at $24,310 per aircraft, or about $413,000 across the US-registered set.

Boeing said the directive is the next step in a process that began in 2019, when the company found an outdated method for measuring shims. It said the method was corrected in production and that aircraft in the global fleet may continue normal operations. Updated operator guidance went out in August 2025. The company says it has spent the past year aligning inspection schedules with airlines.

The gap issue is not new to the 787 file. A whistleblower two years ago alleged that Boeing failed to close gaps properly and used too much force to make parts fit, and that those shortcuts could affect structural integrity. The AD does not adjudicate that claim. It treats a measured risk at a defined joint and orders a check.

Airlines will fold the work into heavy checks where they can. Ultrasonic inspection of splice plates is not a gate-turn task. The 77-aircraft list is small enough that most operators will have one or two tails in the set, not a fleet-wide ground. The risk the FAA is pricing is a crack that is missed between visits, not an immediate fleet pause.

The 787’s airframe is about half composite by weight. The joint in this AD is still a fastener-and-shim problem in metal fittings at the side of body. That is why the measuring method from 2019 matters. A shim that is too thin or too thick changes the force in the hole. Repeated pressurisation and wing bend then do the rest.

Boeing’s line is that production has used the corrected method for years and that the AD is a catch-up for earlier jets. Operators on the 77-aircraft list now have a legal duty to inspect on the FAA’s clock. Jets not on the list keep the existing maintenance programme. The first public signal of whether the theory matches the metal will be the first crack finding, if one appears.