What happened
The aircraft involved was a Twin Quad prototype, specifically the first unit built under the certification program. At the time of the accident, the crew consisted of two pilots and two engineers who were conducting a test flight. Immediately after liftoff, while the twin-engine machine was in its initial climb phase, it entered an uncontrolled stall. The aircraft subsequently crashed to the ground, resulting in total destruction of the airframe.
The crash resulted in one fatality among the four occupants on board. The co-pilot lost their life in the incident, while the pilot and two engineers sustained injuries. Following this event, the development project for the Twin Quad was officially terminated.
Findings
Investigations into the accident identified a specific sequence of events leading to the loss of power. During the flight, the crew encountered an electrical fire. While attempting to combat this emergency, an inadvertent cutting off of an emergency master switch occurred. This action caused both engines to shut down simultaneously. The resulting loss of thrust led to the stall and subsequent crash.