Accident Overview
Approximately five minutes after takeoff, the pilot initiated a high-speed low pass over the airport. When the aircraft was about 1000 feet from the airport at an altitude of roughly 100 feet above ground level, the right winglet separated from the wing. A witness estimated the aircraft's speed to be about 200 miles per hour. Subsequently, the aircraft rolled inverted and crashed.
Examination Findings
A post-accident examination revealed that the winglet had not been installed in accordance with the designer's plans. Specifically, the design called for an 8-ply fiberglass build-up on the outside radius from the lower wing to the outside surface of the winglet. This build-up was not incorporated. The designer estimated that the winglet had less than 1/20 of the design strength.
Aerodynamic Loading
At high speed with zero sideslip, there is an inward aerodynamic bending load on the winglet equivalent to a 15-degree sideslip at low speed. The winglet had failed inward, consistent with this loading.
Additional Deviations
The examination also noted a number of other deviations from the designer's plans, though these were not specified in detail.