Accident Sequence
On December 7, 2017, at about 1600 Pacific standard time, a Cessna 172D, registration N2351U, was substantially damaged during a landing attempt near Auburn, Washington. The private pilot, who was operating the airplane under Title 14 Code of Federal Regulations Part 91 as a personal flight, reported no injuries.
The pilot stated that after turning onto the final approach leg of the airport traffic pattern, he set the flaps to 30° at an indicated airspeed of 70 miles per hour. Approximately 20 to 25 seconds later, the airplane's nose yawed sharply to the left without any control input. The pilot countered with right rudder, and the nose then veered to the right. He noticed that there was no response from left aileron control inputs. The pilot attempted to stabilize the airplane using rudder inputs and initiated a go-around by applying engine power. As power was added, the lack of aileron response became more pronounced, prompting the pilot to reduce power and proceed with the landing. The airplane touched down briefly on the runway surface at about a 45° angle to the runway heading, then exited the right side of the runway and struck a water retention pond. The aircraft came to rest upright in a nose-low attitude.
Damage and Examination
Both wings remained attached to the fuselage at their mounts. The right wing exhibited buckling from approximately mid-span of the flap inboard to the wing root. Measurements along the rear spar from the root to the wing tip showed the right wing was about 3/4 inch shorter than the left, consistent with the buckling damage. The right-wing fiberglass tip was separated and showed scraping along the trailing edge, exposing underlying material. The bottom side of the wing, where the fiberglass tip attaches to the wing structure, displayed scraping.
Examination of the runway revealed a scrape mark containing red paint matching the right-wing tip.
Control System Examination
No evidence of any preexisting mechanical malfunction was found. Control yoke inputs resulted in minimal aileron movement. The control cables from the control chains were continuous from the control column chains through the airframe to the left and right aileron bellcranks. The balance cable remained attached to both bellcranks. All control cable pulleys were secure at their mounts, with the aileron cables still in the pulley grooves. The control cable turnbuckles were attached and safety wired. Due to the buckling in the right wing, aileron control cable tension could not be measured.