Pilot Communications and Weather Conditions
The pilot's last radio communications indicated that the aircraft was in instrument meteorological conditions (IMC) and experiencing updrafts and ice accumulation on the structure. Weather reports for the area included widely scattered thunderstorms and rain. Forecast conditions indicated light to occasional moderate rime and mixed icing in precipitation from the freezing level to 12,000 feet, with moderate turbulence reported across the entire state.
Witness Observations
Ground witnesses heard the sound of the aircraft's engine but could not see the airplane due to cloud cover. They reported a "pretty nasty looking cloud" accompanied by thunder in the vicinity. Subsequently, they heard a sound similar to a sonic boom, after which the engine noise ceased.
Accident Site Evidence
Examination of the accident site revealed that the aircraft broke up in flight. The left wing separated at the wing root, and the right wing separated approximately 109 inches from the root. Both horizontal stabilizers and the vertical stabilizer separated from the empennage. Metallurgical analysis of the fractured components indicated that all separations were typical of overstress failures. The wings and horizontal stabilator failed under a downward loading condition.