What happened
During an instructional flight conducted in instrument meteorological conditions and icing, the crew reported several technical difficulties to air traffic control. The pilots initially communicated issues regarding the autopilot and navigation, which they later stated had been resolved, before reporting a malfunction with the left-side attitude indicator. Following clearance to their destination, the aircraft entered a descending left turn that progressed into a 360-degree descending spiral. This sequence led to an inflight breakup, with the wreckage distributed across more than 7,000 feet of forested area.
Findings
Investigations into the aircraft's mechanical state found that the engines were functioning normally and the pitot-static system was free of blockages. While the left wing deice valve was found to be inoperable due to corrosion, recent pilot reports in the vicinity indicated only light icing, and the aircraft had performed a 6,000 feet per minute climb shortly before the loss of control, suggesting icing was not the primary cause of the loss of control.
Regarding the crew, the pilot in the left seat was not type-rated for the specific aircraft model being flown, though they were scheduled for training to obtain such a rating. The pilot in the right seat held the necessary rating and a flight instructor certificate. While toxicology tests found trace amounts of diphenhydramine in the right-seat pilot, the levels were insufficient to suggest impairment.
Ultimately, the investigation concluded that the reported instrumentation issues likely increased the crew's workload and contributed to task saturation. The difficulty managing the reported autopilot and attitude indicator issues while flying in IMC likely led to spatial disorientation, which caused the aircraft to deviate from its assigned flight path and eventually enter the fatal descent.