NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The private pilot and the pilot-rated passenger reported that, while in level flight at an altitude of 2,000 ft mean sea level with the autopilot disengaged, the airplane suddenly rolled to the right without any control input. The pilot stated that he tried to correct with opposite aileron, but the airplane did not respond and continued to roll inverted. The pilot-rated passenger then took control of the airplane, shut off the engine, and applied full left rudder to bring the airplane back to level flight; however, the airplane had descended to about 300 ft. The pilot-rated passenger slowed the airplane and flared it into trees. The pilot stated that he had no idea what caused the airplane to suddenly roll, that the ailerons were unresponsive, and that he assumed a flight control cable had “snapped.” The pilot-rated passenger stated that they were not trying to perform aerobatics and that he thought the airplane rolled due to a broken aileron cable.
Examination of the accident site revealed that the airplane first struck a 30- to 40-ft-tall tree with its right wing, then struck a second tree with the right wing. A 9-ft-long section of the right wing separated from the airplane and was found at the base of the second tree. Examination of the wreckage revealed that the right aileron UP flight control cable was separated at the turnbuckle, which was located inside the cabin, and the aileron balance control cable was separated in the right wing. Metallurgical examination of the cables revealed that they had both separated from overstress, indicative of the cables separating during the accident sequence. Examination of the airplane’s flight controls did not otherwise reveal any evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation.