FAA warns of uncommanded flap movement in Bombardier jets causing loss of control

The FAA has issued a proposed new airworthiness directive (AD) for all Bombardier Challenger 600, 601, 601-3A, 601-3R and 604 aircraft. The proposed AD would require an update to the aircraft's existing aircraft flight manual (AFM) to provide the flight crew with procedures to follow in the event of an uncommanded, unarrested flap movement. The revision cost is estimated to cost $85 per aircraft. The proposal is related to Transport Canada's own AD that it released in Feb. 2023. It made this proposal after a Challenger 604 experienced an in-flight uncommanded flap movement from 0 to 45 degrees accompanied by a FLAPS FAIL caution. The system should have stopped at 3 degrees, but a failed retract relay prevented the system from arresting the uncommanded movement. While the incident aircraft was able to return to its departure airport without any issue, uncontrolled movement could cause loss of control of the jet. While the Canadian AD required operators to advise all flight crews on revisions to the AFM, the FAA only requires operators to make sure the pilots are aware of and familiar with the changes. Those who are looking to buy any Challenger 600 variants should be aware of a potential flap control relay failure and decide if that is something that they can deal with. Those who already own or fly should familiarize themselves with the revisions and what to do in the event of an uncommanded, unarrested flap movement. Comments on the FAA's Proposed AD is open until July 10, 2026. RELATED STORIES: Emergency AD issued by FAA and Brazil's ANAC for Embraer business jets EASA warns of stolen, unairworthy parts may be on the open market FAA warns of unapproved parts that were sold by Superior Panel Technology