Accident Sequence
During an IFR flight at 7,000 feet MSL, the pilot encountered convective weather activity. Subsequently, the airplane broke up in flight. The breakup included separation of both outer wing panels, the vertical stabilizer, the right horizontal stabilator, and the outboard portion of the left horizontal stabilator. Deformation indicated upward failure of the wings and downward failure of the stabilators.
Weather Conditions
The Area Forecast was indicating widely scattered thunderstorms for an area that included the accident location; however, there were no Convective SIGMETs or Center Weather Advisories in effect. Cloud bases were near 800 feet, and cloud tops were above 15,000 feet. There was moderate or greater convective turbulence below 10,000 feet, with up and downdrafts and horizontal wind gusts. Also, there were embedded thunderstorms, and the freezing level was above 14,000 feet. Two ground witnesses stated that when they observed the airplane, 'very hard' rain was falling with lightning and thunder.
ATC Communication
Investigation revealed that ATC had issued a warning about a thunderstorm ahead and had provided clearance for a vector around the weather. The pilot did not respond, and about 20 seconds later, the transmission was repeated. The pilot acknowledged and initiated a turn, but radar and weather data showed that the airplane tracked to about 2 nautical miles from a Level 5 to Level 6 thunderstorm. The airplane then entered a descent and crashed.