What happened
During the accident flight, a flight instructor (CFI) was conducting the final stages of preparation for a second pilot's multiengine CFI check ride. Following a touch-and-go landing, the aircraft climbed to an altitude between 200 and 300 feet AGL.
While attempting to retard the throttle on the left engine, the instructor accidentally retarded the propeller control into the feather detent. As the pilot maneuvered the aircraft while attempting to restart the left engine, the airplane bypassed several suitable landing sites. The aircraft entered a gradual descent over hilly terrain. As airspeed decreased, the pilot lost control of the aircraft, resulting in a left roll and a collision with the terrain.
The investigation
The left engine and propeller assembly were removed from the aircraft and placed in an engine test cell for examination. Testing revealed that the engine, propeller, and propeller governor functioned normally throughout their normal operating ranges.