Incident Description
During the takeoff roll, the aircraft used a runway consisting of 700 feet of concrete followed by 1,600 feet of wet turf. As the aircraft progressed onto the wet turf section, the left main landing gear tire encountered a soft rut. This caused the airplane to yaw to the left. The pilot reported that his head struck the roll-bar during the event.
Sequence of Events
After the yaw, the pilot attempted to recover. However, by the time he regained control, the aircraft had slowed sufficiently that it impacted a ditch at the end of the runway. The impact caused the aircraft to nose over.
Aircraft and Engine Status
The pilot did not indicate any mechanical problems with the airplane. He stated that the engine power remained at full throughout the takeoff roll.
Operational Conditions
The runway surface conditions included a concrete portion and a wet turf portion. The soft rut in the turf was identified as the trigger for the loss of directional control.