FAA Proposes AD Making AP STAB TRIM FAIL an Emergency Procedure on Challenger 300, 350 and 3500
Why It MattersReclassifying a procedure rather than modifying hardware shows how regulators address pitch-upset risk on a mature business-jet type through crew response and training, shifting the burden to flight departments.
What happened
The FAA has proposed a new airworthiness directive (AD) covering all Bombardier Model BD-100-1A10 aircraft, the platform sold as the Challenger 300, 350 and 3500. The proposal applies to all 680 U.S.-registered BD-100-1A10 airplanes. It is not a redesign or an immediate maintenance requirement; it changes how crews respond to a specific cockpit alert.
The proposal follows reports of pitch upset events. According to the FAA, EICAS messages can indicate that the autopilot is holding significant nose-up or nose-down elevator force. Delays in responding, and failure to stabilize airspeed, can leave the horizontal stabilizer severely out of trim. Disconnecting the autopilot in that state could cause a sudden elevator movement if the control column is not held firmly.
The AD would revise the Airplane Flight Manual (AFM) and move the AP STAB TRIM FAIL procedure, which covers the autopilot failing to trim the stabilizer, from a non-normal procedure to an emergency procedure. The aim is to give crews immediate steps to stabilize airspeed before stabilizer trim conditions worsen.
The FAA estimates compliance at $85 per aircraft, though operators may face additional internal costs for reviewing procedures, updating training materials and familiarizing crews with the revised guidance. The FAA notes that operators are already required to furnish AFM revisions to pilots and ensure crews are familiar with them, and that training on updated AFM content is recorded in each pilot's training record.
The FAA calls the proposal an interim action, the same label Transport Canada applied to its own AD last year, and says it might consider further rulemaking if a final action is later identified. Comments are open until Oct. 29 through Docket FAA-2026-8808.
Industry impact & what to watch
An AD that rewrites a flight-manual procedure instead of ordering a part change is the lightest tool a regulator has for a handling risk, and the $85 per-aircraft estimate reflects that. The real cost sits elsewhere: the time flight departments and training providers spend revising checklists, briefing crews and recording the new content. On a type flown across charter, fractional and corporate operations, how quickly that content reaches every pilot is the practical measure of the directive.
The emergency classification matters because it changes what a crew is expected to do from memory. Emergency procedures are generally treated as immediate-action items, which pushes the AP STAB TRIM FAIL response toward recurrent simulator training and away from something a pilot looks up after the fact. Operators with mixed fleets or high crew turnover will feel that more than owner-pilots flying a single aircraft.
The FAA describes this as an interim action and mirrors Transport Canada's earlier AD, so the two regulators are currently aligned on the procedural fix. The next dated milestone is the Oct. 29 comment close on Docket FAA-2026-8808, after which the FAA will decide whether the proposal becomes a final rule or prompts the further rulemaking it mentions.
