The Federal Aviation Administration (FAA) has proposed an airworthiness directive requiring inspections on certain Boeing 787 aircraft for fatigue cracks stemming from excessive shim gaps in structural components.
Released on March 12, 2026, the directive targets manufacturing errors involving overly large gaps between fuselage sections, particularly at lower side-of-body splice plates. These gaps, caused by excessive pre-load forces during assembly, could weaken primary wing structures, potentially preventing them from sustaining limit loads.
Boeing identified the issue and issued an Alert Bulletin in August 2025, directing operators to check splice plates, spar terminal fittings, chords, and jack pads for cracks. The FAA proposal mandates these inspections and fixes, but applies only to 17 U.S.-registered 787s, likely based on production dates. Public comments are open for 45 days.
The agency states Boeing’s current structural inspection program lacks sufficient probability to detect cracking in principal elements before failure. Boeing supports mandating the guidance, noting the global fleet can operate normally as the root cause has been corrected in production.
Shim gaps arise during fuselage joining: workers apply fit-up force, insert shims to fill voids, then add pull-up force with splice straps and fasteners. Boeing’s chief engineer Steve Chisholm highlighted full-scale fatigue tests simulating 165,000 flights yielded zero findings in the composite structure. Past rework addressed undelivered jets exceeding FAA specifications, without compromising flight safety.
This follows separate FAA proposals for forward pressure bulkhead inspections on nearly 1,000 787s due to assembly nonconformances like gaps trapping debris, risking undetected fatigue.