What happened
During the climb-out phase following takeoff, at an altitude of approximately 200 feet above ground level, the left wing of the aircraft folded upward just outboard of the lift strut attachment points. Following this structural failure, the aircraft entered a vertical descent. During this descent, the trailing wing section remained attached to the airframe via what witnesses believed were control cables, though the forward left wing lift strut eventually separated from the aircraft. The aircraft continued its vertical descent until it collided with the ground.
The investigation
An NTSB metallurgist examined sections of the forward and aft lift strut attach fittings and fork assemblies from the left side of the aircraft. The metallurgical analysis determined that all observed deformation and fracture features were consistent with overstress fractures resulting from a bending load.
Additionally, a review of historical maintenance documentation was conducted. The records indicated that the pilot, who was not a certified mechanic, had been performing extensive structural maintenance on the aircraft since the late 1970s. Following these self-performed repairs, a certified mechanic would sign off on the work.