PDF translated full report.
An accident took place in the northwestern part of the Moscow Terminal Control Area (TMA) on Thursday, 23 December 2010 at 16:10 UTC. While enroute from Moscow to St Petersburg, a Bombardier BD–100–1A10 Challenger 300 business jet, registration OH-FLM, experienced a sudden in-flight pitch upset during the climb. There were three passengers and three crew-members of the on board. As a result of the occurrence two passengers were injured and some of the cabin interior was damaged. The aircraft returned to Sheremetyevo Airport and the injured passengers were taken to hospital in Moscow.
The flight was a familiarisation flight for the co-pilot in accordance with the European Union Regulation on Air Operations (EU-OPS). Before the flight it was agreed that the co-pilot would act as the Pilot Flying (PF).
The course of events began during the initial climb when the Engine Indication and Crew Alerting System (EICAS) annunciated an Autopilot Stabilizer Trim Failure (AP STAB TRIM FAIL) warning. In accordance with the fault checklists the captain disengaged the autopilot. This resulted in a porpoising oscillation which was quickly brought back under control. Whereas the aircraft’s checklists advise the pilots to firmly grip the control column prior to AP disengagement, they do not instruct the flight crew to consider adjusting the airspeed to correspond to the horizontal stabilizer angle. Neither did the checklists include any mention of turning on the Fasten Seat Belt sign.
The cause of the occurrence was the overcontrolling of the aircraft’s pitch attitude immediately after the autopilot was disengaged. Contributing factors included the pilots’ unfamiliarity with the characteristics and operating principle of the aircraft’s artificial pitch feel system as well as shortcomings in system training. Further shortcomings were also observed in the flight crew’s checks and in crew cooperation. High airspeed was yet another contributing factor to the considerable acceleration (g) forces experienced during the upset.
The investigation commission issued three safety recommendations:
Safety Investigation Authority, Finland recommends that the operator ensure that Standard Operating Procedures as well as pre-takeoff checklists support flight crew action when it comes to confirming the critical takeoff-related issues immediately before takeoff.
Safety Investigation Authority, Finland recommends that Transport Canada review the content of Bombardier CL300-type aircraft QRH checklists as regards horizontal stabilizer trim system faults.
Safety Investigation Authority, Finland recommends that the European Aviation Safety Agency (EASA) call attention to the content of the type training classroom instruction and simulator training of artificial feel system operating principles, especially with regard to aircraft types in which the system does not directly adjust in relation to airspeed.