CHI02LA255

The pilot reported his seat slid rearward during a takeoff from a gravel road, resulting in a loss of directional control. The aircraft veered off the road and went down an embankment. The seat and its positioning system were examined. The unintentional rearward movement of the seat, as described by the pilot, could not be duplicated. The seat moved freely along the seat tracks, with the latch pins engaging the pinholes. The seat could be twisted (racked) resulting in the outboard latch pin engaging a pinhole and the failure of the inboard latch pin to engage a pinhole. If the seat was displaced in the forward direction, both latch pins engaged a pinhole.

On August 19, 2002, at 1110 central daylight time, a Cessna 172P, N381J, piloted by an airline transport pilot, sustained substantial damage while performing a takeoff from a gravel road near Buffalo City, Wisconsin. Visual meteorological conditions prevailed at the time of the accident. The business flight was operating under the provisions of 14 CFR Part 91 without a flight plan. The pilot reported no injuries. The flight was originating at the time of the accident and had the intended destination of Winona, Minnesota.

According to the pilot's written statement, "On take off, after applying full power and rolling for about 20 to 30 feet, the seat slid back full aft preventing me from reaching the rudder pedals. Therefore I could not maintain the directional control nor I could bring the plane to a stop. I tried to pull the seat forward but it was locked aft and the seat belt & shoulder harness prevented me to move forward. I pulled the power back- the plane had already veered to the left in an embankment 15 [feet] deep."

An inspector with the Federal Aviation Administration (FAA) and a representative of the Cessna Aircraft Company conducted post accident examinations of the airplane. The seat positioning system was a dual latch pin design. The seat tracks had light wear markings, the seat base and attachment feet were worn and the vertical supports of the seat base flexed inboard and outboard approximately 0.20 inches. The seat moved freely along the tracks and the latch pins engaged the pinholes along the tracks. The seat could be twisted (racked) resulting in the outboard latch pin engaging a pinhole and the failure of the inboard latch pin to engage a pinhole. If the seat was displaced in the forward direction, both latch pins engaged a pinhole.