What happened
While surveying a field for potential future work, the pilot experienced a loss of control of the aircraft. In response to the loss of controllability, the pilot selected an emergency landing area and executed a forced landing in a field. During the landing sequence, the left wing struck the ground, causing the aircraft to cartwheel and sustain significant structural damage.
The pilot was not injured during the event.
The investigation
An examination of the aircraft focused on the left aileron control mechanism. Investigators found that the bolt used to secure the left aileron to the control surface had separated from the assembly. Upon removal of the aileron, the missing bolt was located within the inter-structure of the wing area.
Further inspection of the bolt assembly revealed that the bolt connecting the forward end of the control rod to the bell crank was too short; it failed to protrude sufficiently through the nylon lock nut. Additionally, the investigation determined that the rod-end bearing was seized and unable to move.