A Bombardier Challenger 300, N300ER, encountered an upset when the flight crew disconnected the autopilot while suffering from a nose-up mistrim situation. The mistrim was the result from a failure of the autopilot stabilizer trim control. The upset resulted in a roller coaster exceeding +4g and -2g, eventually brought under control by the flight crew. Tragically, a passenger was fatally injured in the upset.
The flight crew made several mistakes unrelated to the upset. They also apparently disregarded the caution alerting them to the mistrim. The NTSB preliminary report provides an account of the accident. The final report will provide analysis and probable cause. This post goes through the preliminary report and offers some additional commentary and excerpts from an operation manual of the same type aircraft.
