What happened
Approximately one hour before takeoff, the pilot obtained a weather briefing that included discussions regarding thunderstorm activity along the intended flight route. About two hours and 30 minutes into the flight, while attempting to deviate around thunderstorm activity, the aircraft disappeared from radar.
A witness located near the accident site reported hearing the engine revving up and down, followed by a muffled pop and then silence. The witness subsequently observed debris falling from the sky at an altitude well above the tree line.
The investigation
An examination of the aircraft revealed that it had experienced an in-flight breakup, though investigators found no evidence of a mechanical malfunction. Weather radar imagery indicated that the aircraft had entered a developing area of moderate to heavy intensity echoes, which were consistent with a convective cell or thunderstorm.
At the time of the accident, there were no active Convective SIGMETs, SIGMETs, or Center Weather Advisories for thunderstorms covering the area of the accident site. The pilot reported receiving weather information via a portable GPS receiver using a weather subscription service.
Findings
The pilot had received a multiengine rating on May 13, 2006. At the time of the accident, the pilot had accumulated approximately 1,720 total flight hours, which included 32.6 hours in multiengine aircraft, 26.8 of which were in the involved airplane. While the pilot had logged approximately 140 hours of actual instrument flight and 68 hours of simulated instrument flight, the pilot had not logged any additional instrument flight experience in multiengine airplanes beyond 0.4 hours of simulated experience recorded during a multiengine rating check ride.