What happened
The pilot was operating an airplane on a downwind track while descending in slow flight. The aircraft had its flaps extended to ten degrees as the pilot intended to inspect a piece of property he planned to purchase. During this maneuver, another aircraft flew past at a low altitude and executed a sharp bank away from the accident airplane.
Immediately following this event, the wings of the accident airplane began to wobble. The nose then dropped significantly, leading to an impact with the ground in an open wheat field.
The investigation
The physical evidence indicated that the aircraft was operating at a low altitude and slow airspeed during the final phase of flight. The interaction with the second aircraft occurred just prior to the loss of control.
Findings
The pilot was engaged in slow flight with flaps extended while descending on a downwind leg. A second aircraft passed nearby at low altitude and banked sharply. This sequence resulted in the wings wobbling, the nose dropping, and subsequent impact with the terrain.