What happened
The aircraft performed two passes over a private residence. The purpose of these maneuvers was to alert a friend on the ground, instructing them to proceed to a nearby agricultural airfield to retrieve the pilot and passengers. After the initial passes, the aircraft remained in the general area, flying at low altitude and slow speed.
A friend of the occupants observed the aircraft from the ground while making their way to the designated pickup location. During this time, the observer briefly looked away from the aircraft. Upon looking back, the observer witnessed the aircraft entering a spin and descending rapidly toward the ground.
The investigation
Post-accident examination of the wreckage revealed that the wing flaps were found in the full down position.