Aircraft Accident/Incident Report

Jackson, Wyoming 83001
Monday, June 27, 2005 12:25 MDT

Several witnesses reported that the airplane departed runway 19, and immediately climbed to approximately 500 feet above ground level (agl), while maintaining runway heading. The airplane then turned left onto the crosswind leg of the traffic pattern and maintained a slight climb. One witness, who was in a vehicle, observed the airplane in normal flight on a left downwind for runway 19 at an altitude of 800 to 1,000 feet. The witness observed the airplane turn left (west) onto the base leg for runway 19 "in normal flight and was descending but not what appeared to be abnormal." The airplane continued its nose-low descent toward the terrain until approximately 200 feet agl, the airplane began a "steeper" nose-low descent toward terrain. The airplane then impacted terrain in a wings level attitude, bounced, nosed over, and came to rest inverted. During the descent, the witness did not noticed any movement of the elevator or other flight control surfaces, or any in-flight structural failure of the airplane. The accident flight was the third flight conducted by the pilot since he had completed repairs after sustaining a hard landing with the airplane. In order to complete the repairs to the airplane, the pilot had to removed the elevator and aileron controls located in the boom tube. NTSB materials laboratory examination of the aileron and elevator controls revealed no features or marks were found at a location of approximately 5/16-inch forward of the original location of the rear locking collar on the torque tube surface, with the exception of two distinct circumferential marks. The featureless surface, confirmed by testing, indicated that the locking collar was slightly torqued and that the torque tube had moved relatively slowly over this distance, possibly with two stops. The torque required to loosen the rear locking collar screw was measured at 3-inch pounds, representing a minimal snugging of the collar bolt and collar on the torque tube. According to the manufacturer, a 3/16-inch aft movement of the torque tube would be enough to lose any tension in the elevator control cables. The rear edge of the cutout on the boom tube for the rear control stick displayed three locations where paint had been removed, but there was no material deformation. The lack of deformation is consistent with light contact by the control stick, which would be expected if the control stick had been pulled rearwards manually. A lightly rubbed area on the aileron crank revealed laterally orientated arced lines on the surface and corresponding laterally orientated smeared surface on the upper front bulkhead tube. No evidence was found to indicate that an inspection mirror had been trapped in the boom tube.

The loss of airplane pitch control resulting from the pilot/owner's improper reinstallation of the rear locking collar on the elevator control torque tube, which allowed the torque tube to move rearward during flight and loosen the elevator control cable tension.