What happened
During the flight, the pilot's final radio communications indicated that the aircraft was operating in instrument meteorological conditions. The crew reported experiencing updrafts and the accumulation of ice on the airframe. The surrounding area was characterized by widely scattered thunderstorms and rain, with light to occasional moderate rime and mixed icing present from the freezing level up to 12,000 feet. Moderate turbulence was also reported throughout the state.
Witnesses on the ground reported hearing the sound of the aircraft's engine but were unable to see the plane. They described a severe thunderstorm in the area accompanied by thunder. Witnesses then heard a sound similar to a sonic boom, after which the sound of the engine ceased.
The investigation
Evidence recovered from the accident site confirmed that the aircraft broke up in flight. The structural failure involved the separation of the left wing at the root and the right wing approximately 109 inches from the root. Additionally, both horizontal stabilizers and the vertical stabilizer separated from the empennage.
A metallurgical examination of the fractured components was performed. The results indicated that the fractures were typical of overstress separations, specifically showing that both wings and the horizontal stabilator failed under a downward loading condition.