Overview
A pilot conducting a post-flight pattern flight experienced an accident shortly after lift-off, resulting in the aircraft crashing on the runway. The pilot had previously flown the aircraft with students earlier in the day and followed a personal habit of completing one pattern flight before securing the aircraft in the hangar.
Investigation Findings
During the investigation, evidence was discovered in the rear cockpit indicating that the seat belt was wrapped around the aft control stick. The fraying and damage on the seat belt corresponded to the location where the adjustment buckle would have been if the belt had been wrapped once around the stick and buckled with the stick in the full aft position.
Conclusion
The investigation did not explicitly assign a probable cause, but the physical evidence suggests a potential obstruction of the control stick by the seat belt.