Departure into IMC
The instrument-rated private pilot and a passenger departed into instrument meteorological conditions with a 600-ft cloud ceiling. The airplane was about 550 lbs over its maximum gross weight. Air traffic control data showed the airplane making a climbing left turn that continued beyond the assigned heading.
Erratic Flight Path
After reaching 1,400 ft mean sea level, the airplane continued turning left while its altitude and speed began to vary. It then entered a left spiral, completing more than two full circles. Subsequently, the airplane decelerated in a right turn and rapidly descended until impact with terrain.
Aircraft and Autopilot Examination
Examination of the flight control system revealed no evidence of mechanical malfunctions. Downloaded engine data indicated normal engine operation. Data from the autopilot system showed three in-flight error codes. The first error code, which likely occurred about 1 minute after takeoff, would have resulted in the autopilot disengaging if it was engaged at that time. The subsequent error codes likely occurred during the erratic flight profile, with the autopilot disengaged.
Pilot Background and Toxicology
Before the accident flight, the pilot had informed a mechanic (who is also a pilot) of intermittent issues with the autopilot system and that these issues were unresolved. The mechanic had flown with the accident pilot previously and assessed his instrument flying skills as weak. The flight instructor who provided initial flight training for the turbine engine transition stated the pilot's instrument flying proficiency was poor when hand-flying the airplane.
Toxicology testing revealed that the pilot had used marijuana. His girlfriend stated the pilot would take a marijuana gummy before bedtime to sleep more soundly. However, given that no psychoactive compounds were found in blood specimens, it is unlikely that the pilot was impaired at the time of the accident.
Conclusion from Investigation
The instrument conditions at the time of the accident, the airplane's erratic flightpath, and the pilot's reported lack of instrument proficiency when flying by hand support the likelihood that the pilot experienced spatial disorientation sometime after takeoff. In addition, given the reports of the intermittently malfunctioning autopilot that had not been fixed, it is likely the pilot experienced an increased workload during a critical phase of flight that, in combination with spatial disorientation, led to the pilot's loss of airplane control.