What happened
The accident occurred while the aircraft was accelerating for takeoff. According to the pilot, the seat had been properly locked in place prior to taxiing. However, as the aircraft gained speed, the pilot's seat slid aft along its track. This movement prevented the pilot from maintaining adequate control inputs and directional control of the aircraft.
Consequently, the aircraft departed the left side of the runway. It continued forward, rolling through high grass, which caused the nose gear to collapse and the aircraft to nosed over.
The investigation
NTSB investigators conducted both visual and functional checks of the pilot's seat mechanism after the accident. These examinations revealed no evidence of mechanical malfunctions or failures in the seat locking system that would have allowed it to slide during normal operation.
Findings
The primary factor contributing to this accident was the failure of the pilot's seat to remain locked in position during the high-vibration environment of takeoff acceleration. This resulted in an inability to maintain directional control, leading to a runway excursion and subsequent structural damage to the nose gear.