What happened
During a horse sale held at a ranch, the individual operating the aircraft had been providing aerial rides to attendees. The flight pattern typically involved taking off from a nearby field and performing several low passes that concluded with steep pull-ups.
On the flight resulting in the accident, the operator performed a low pass followed by a steep pull-up. As the aircraft reached the top of the maneuver and began to lose airspeed, it appeared the operator attempted to initiate a turn. At this point, the aircraft entered a spin. The individual operating the aircraft was unable to recover from the spin.
Witnesses at the ranch event reported that the person flying the aircraft had previously stated to several people present that he did not hold an FAA pilot's certificate. Subsequent investigations of FAA records confirmed that the operator was not a certificated pilot.