Primary finding
Probable cause
The failure of the wing fabric and wing spar. Factors were: the improper design change, major repair, and rebuilding of the aircraft by the pilot in command.
Investigator assessment
Analysis narrative
The unregistered airplane was seen to make a hard left turn and enter a vertical dive from an altitude of between 100 and 150 feet. At an altitude of about 75 feet, the fabric separated from the right wing and the wing failed. Post accident investigation disclosed the rudder control cable was frayed, had broken, and was of the wrong size. The wing fabric was deteriorated, had been previously patched, was of the wrong type and weight, and bore spanwise tears. The wing spar had failed at a point where previous repairs had been made. Additionally, the wing ribs were of the wrong type. The pilot had converted what had been a single place ultralight vehicle into a two place airplane by using parts from wrecked ultralights, causing the empty weight to exceed the maximum allowable.
Source record
Factual narrative
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