Accident Sequence
The accident occurred while the aircraft was performing a test flight. According to witnesses, the aircraft yawed 180 degrees around its vertical axis, then pitched nose-down and descended vertically to the ground. During this maneuver, witnesses noted a change in engine noise, which they described as either a sputter or a change in tone. The aircraft subsequently struck the terrain.
Post-Accident Inspection
Following the accident, a detailed inspection of the engine was conducted. The magneto was found to be loose; it could be rotated radially about its drive shaft by nearly 60 degrees. Additionally, a puncture was discovered in the engine case directly below the lower swash plate assembly. Except for these two findings, no other discrepancies were identified.