On July 9, 1994, at 1530 Pacific daylight time, a Pezetel M- 18 Dromader, N4685R, collided with terrain while maneuvering to make a pass for aerial application on fields 8 miles west of Plymouth, Washington. The airline transport rated pilot, who was the sole occupant of the aircraft, received minor injuries, and the aircraft sustained substantial damage. Visual meteorological conditions prevailed at the time of the accident. No flight plan had been filed, and there was no report of an ELT activation. According to the pilot, as he pulled up to make a left turn, he applied considerable left rudder. As he entered the descending part of the turn, he began to roll out, and attempted to apply right rudder, but the rudder pedals were jammed in almost the full left rudder position. Being low to the ground, the pilot was unable to arrest the descending turn before the aircraft impacted the terrain. Inspection of the rudder and the rudder control system did not reveal the reason why the system jammed. The pilot was sent copies of NTSB Form 6120.1/2 on two separate occasions, but in both instances he elected not to return them.