FAA Proposes Airworthiness Directive for Bombardier BD-700-2A12 Over Wing Rib 6 Fuel Leak and Structural Risk

The Federal Aviation Administration issued a notice of proposed rulemaking on September 9, 2026 to adopt a new airworthiness directive targeting certain Bombardier, Inc. Model BD-700-2A12 airplanes, under Docket No. FAA-2026-8797 (Document No. 2026-18376).

The proposed AD followed reports of fuel leakage near wing rib 6 discovered during production pressure testing. An investigation found five oversized holes in the outboard shear-tie between stringers 8L and 9L attaching rib 6 to the lower wing skin, identified after removal of the doubler on rib 6 near stringer 8L. A fatigue analysis indicated that oversized holes in the inboard and outboard shear-ties at that location present a potential for crack formation, which, if left unaddressed, could lead to failure of the shear-ties and loss of redundant structure.

The proposed AD would require inspection of fasteners and fastener holes at rib 6 for discrepancies — including gaps under nuts, nut loosening, oversizing, elongation, ovalization, and cracking — with on-condition actions such as repair and fastener reinstallation where needed. The requirements mirror those of Transport Canada AD CF-2025-39, with any differences noted in the regulatory text. The compliance time was derived from a fatigue analysis based on the fleet leader and was set from the issuance date of Bombardier Service Bulletin 700-57-7525, dated October 26, 2022. The FAA must receive public comments on the proposed AD by October 26, 2026, submitted via the federal docket under FAA-2026-8797.

This case follows a familiar sequence in transport-category certification: a production-line finding, such as a pressure-test leak, triggers a fatigue analysis, which then becomes a service bulletin and eventually a mandatory directive once a regulator determines the risk of undetected structural degradation is unacceptable. The shear-tie is described as redundant structure, so the FAA's proposed action is aimed at catching a fastener-hole defect before it can propagate into a crack that removes that redundancy.

Cross-border regulatory mirroring is standard practice for aircraft type-certificated in multiple jurisdictions — Transport Canada's AD CF-2025-39 already covers the same discrepancy, and the FAA's proposal is built to align with it rather than diverge, which keeps compliance burden consistent for operators flying the type under either authority. Bombardier's service bulletin date anchors the compliance clock, meaning operators' inspection timing depends on fleet-leader flight hours rather than calendar time alone.

The open question is what the FAA does with the comment period closing October 26, 2026: whether public or operator input shifts the inspection scope, compliance time, or on-condition repair criteria before the directive is finalized.