Sport parachute jumping was taking place over a long weekend. The aircraft being used had been prepared for the task by the removal of the right door, most of the seats and the control wheel on the right side. However, the tube to which the control wheel was attached remained protruding from the instrument panel. The parachute instructor was positioned near the right door opening, with his back to the instrument panel. As the first of the students prepared to take up his position in the door opening, the instructor moved back and pressed against the control wheel tube. This resulted in a nose-down pitch change, which the pilot corrected by pulling back on his control column. Shortly afterwards, the instructor leant back more forcefully and the aircraft adopted a steep nose-down attitude. The pilot shouted that he was unable to control the aircraft, and the instructor then grasped the door frame and exited the aircraft. At this point the aircraft had descended from 2500 feet above the ground to about 1000 feet. The instructor's parachute commenced opening at a height of about 400 feet, but it did not fully deploy before he struck the ground. The pilot regained control of the aircraft and carried out an uneventful landing with the students and the observer still on board. A subsequent inspection revealed that the instructor's equipment was in a serviceable condition at the time of the accident, and there was no evidence that he had suffered any sudden illness or incapacity which might have affected his judgment. A series of tests were undertaken which showed that it was possible that portion of the instructor's clothing may have snagged on the engine controls. However, the reason he subsequently jumped from the aircraft could not be positively determined, nor could the reason he failed to activate his parachute until a low height above the ground.
