Background
Before departing, the pilot obtained a weather briefing and was advised that VFR flight was not recommended through western Nebraska and eastern Wyoming. A frontal weather system was forecast to produce thunderstorm activity with associated turbulence and rain. According to reports, the pilot was anxious to make the flight to deliver needed parts for a machine that was to be used in a publicly advertised demonstration. Additionally, he felt he could help his partner complete the project in time for the demonstration. The pilot elected to file a VFR flight plan and departed as planned.
Flight and Weather
While en route, the aircraft encountered weather and subsequently crashed. Just before impact, the aircraft was seen spiraling after it came out of a low overcast with no right wing or tail section. After the plane crashed, a witness observed the right wing 'drifting down.'
Wreckage Examination
An examination of the wreckage revealed evidence that both horizontal stabilators failed from positive airloads and the right outboard wing section failed from negative airloads. No evidence was found of a malfunction or failure before the inflight breakup.
Conclusion
The aircraft broke up in flight after encountering weather, leading to the crash. The exact sequence of events leading to the structural failure was not determined beyond the observed airload conditions.