N2351U

On December 7, 2017, about 1600 Pacific standard time, a Cessna 172D, N2351U, was substantially damaged when it was involved in an accident near Auburn, Washington. The private pilot was not injured. The airplane was operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot reported that, after turning onto the final approach leg of the airport traffic pattern for landing, he set the flaps to 30° at an airspeed of 70 miles per hour. About 20 to 25 seconds later, the airplane's nose veered sharply to the left without any control input. The pilot stated that he counteracted the movement by applying right rudder and the airplane veered to the right as he noticed that he had no response from left aileron control input. The pilot reported that he tried to stabilize the airplane with rudder inputs and performed a go-around by applying power. As he added engine power, he noticed that the lack of response from the ailerons became more pronounced and decided to reduce power and land. The airplane subsequently touched down briefly on the runway surface, about 45 degrees off runway heading, before it exited the right side of the runway and impacted a water retention pond. The airplane came to rest upright in a nose-low attitude.

Both wings remained attached to the fuselage via their respective mounts. The right wing exhibited buckling from about mid-span of the flap inboard to the wing root. The wing was measured along the rear spar from the root to the wing tip and the right wing was found to be about 3/4 inch shorter than the left, consistent with the buckling damage in the right wing. The right-wing fiberglass tip was separated and exhibited scraping along the trailing edge, exposing the material beneath the paint. The wing exhibited scraping on the bottom side where the fiberglass wing tip attaches to the wing structure.

No evidence of any preexisting mechanical malfunction was observed with the airplane.

Control yoke inputs resulted in minimal movement of the ailerons. The control cables from the control chains were continuous from the control column chains throughout the airframe to the left and right aileron bellcranks. The balance cable remained attached to both aileron bellcranks. All control cable pulleys remained secure at their respective mounts with the aileron control cables still within the grooves of the pulleys. The control cable turnbuckles remained attached and safety wired. The control cable tension for the ailerons could not be measured due to the buckling in the right wing.

Examination of the runway revealed a scrape mark with red paint consistent with the right-wing tip.