FAA proposes safety rule after Bombardier Challenger flaps malfunction

The Federal Aviation Administration (FAA) is proposing a new airworthiness directive for hundreds of Bombardier Challenger jets after one aircraft experienced a dangerous in-flight flaps failure that could have led to a loss of control.

The incident involved a Bombardier CL-600-2B16 in which the flaps moved uncommanded from 0 to 45 degrees during flight – far beyond the intended 3-degree stop – while a FLAPS FAIL warning illuminated in the cockpit. The aircraft returned safely to its departure airport. Investigators found that a failed retract relay prevented the system from stopping the movement.

The proposed rule would require operators to update their aircraft flight manuals with new crew procedures for handling any similar uncommanded flap movement in future. The FAA estimates the update will take one work-hour per aircraft at a total cost to US operators of around $51,850.

The directive would apply to 610 U.S.-registered aircraft across the Challenger 600, 601, and 604 families. It follows a related 2023 directive that introduced operational testing of the flap control system as an interim measure.

The proposal mirrors guidance already issued by Transport Canada, the aircraft’s country of certification.

The FAA is accepting public comments until July 10, 2026, via its regulations.gov portal under Docket No. FAA-2026-4642.