What happened
During a first company training flight, a check airman was instructing a newly hired second-in-command. Following departure, the aircraft performed several standard training maneuvers. Approximately 21 minutes into the flight, while at an altitude of roughly 3,400 feet mean sea level, the aircraft entered a steep descent and struck the ground. Data indicates the aircraft reached a nose-down pitch of approximately -40 degrees, with a descent rate peaking at 16,000 feet per minute.
Findings
An investigation into the flight sequence revealed that the aircraft entered the upset during a specific phase of the training routine where the instructor typically simulates an in-flight emergency and descent. While the aircraft was configured for cruise flight during the initial upset, inspections of the flight control cables showed they remained intact through the impact. However, measurements of the trim actuators revealed an abnormal configuration, with both trim tabs positioned in a trailing-edge-up, nose-down state.
Calculations regarding aircraft performance suggested that during a pitch trim excursion, the physical force required to counteract the anomaly becomes unmanageable without rapid, correct remedial actions. The investigation concluded that the check airman likely simulated a pitch trim excursion. The second-in-command, who was inexperienced with this specific aircraft type, failed to respond appropriately to the event. Ultimately, the check airman failed to implement recovery procedures quickly enough to prevent the control forces from becoming too great to manage, leading to the uncontrolled dive.