The FAA has issued a final Airworthiness Directive requiring repetitive inspections of certain Boeing 787-8, 787-9 and 787-10 aircraft following the identification of manufacturing discrepancies involving shim gaps in a critical wing structure.
The US Federal Aviation Administration (FAA) has mandated inspections of certain Boeing 787 Dreamliners after a Boeing investigation found that shim gaps at the lower side-of-body splice plates may have exceeded engineering specifications.
According to the FAA, the affected splice plates are associated with the lower outboard wing skins. Excessive gaps during assembly can require components to be pulled together with high forces, potentially creating conditions for fatigue cracks to develop around fastener holes. The final Airworthiness Directive (AD), issued on August 26, applies to certain 787-8, 787-9 and 787-10 aircraft.
Under the directive, operators must carry out repetitive ultrasonic inspections of specified structural areas for cracks. These include certain splice plates, rear spar terminal fittings, lower chords, front spar terminal fittings and jack pads.
The AD also requires repetitive detailed inspections of specified splice plates, with applicable corrective actions, including repairs, required if cracks are detected.
Boeing manufacturing issue
The FAA action follows an investigation by Boeing into manufacturing discrepancies dating back to 2019. Boeing identified potential issues involving shim gaps and issued an Alert Requirements Bulletin in August 2025 detailing the inspection requirements. The FAA subsequently proposed making the inspections mandatory in March 2026 before issuing the final directive.
The regulator said that if fatigue cracking remains undetected and progresses, it could reduce the strength of primary wing structure to a point where it may no longer be capable of sustaining its design limit load, potentially affecting the aircraft’s ability to safely complete a flight.
However, Boeing has said the affected aircraft can continue normal operations while operators comply with the inspection requirements.
17 US- registered aircraft affected
The FAA estimates that the directive currently affects 17 aircraft on the U.S. registry. The agency estimates the cost of compliance at up to $24,310 per inspection cycle for each aircraft, resulting in a potential total cost of approximately $413,270 per inspection cycle for US operators.
The FAA received comments on the proposed rule from United Airlines, American Airlines and The Foundation for Aviation Safety during the public consultation period.
The inspection requirement adds another maintenance action to the 787 programme’s history of structural manufacturing and shimming-related issues. However, the latest directive applies specifically to aircraft identified through Boeing’s August 2025 service bulletin and does not represent a new structural finding affecting the entire 787 fleet.
For MRO organisations and 787 operators, the directive will require additional inspection planning and recurring structural inspection activity. The use of ultrasonic inspection techniques will be particularly relevant, requiring operators and maintenance providers to ensure appropriate NDT capability, qualified personnel and access to the affected structural areas.
Where cracking is identified, operators will need to undertake the applicable corrective action in accordance with approved repair instructions.
The FAA’s final directive is intended to ensure that any fatigue cracking associated with the manufacturing condition is identified before it can progress and compromise the structural integrity of the aircraft.
For 787 operators, the requirement highlights the importance of continued structural inspection and monitoring of aircraft affected by the manufacturing discrepancies, while providing a defined regulatory pathway for identifying and addressing any developing cracks.
