What happened
Prior to departure, the pilot obtained a preflight briefing from the Gainesville Automated Flight Service Station. This briefing included warnings regarding potential moderate turbulence between 24,000 and 37,000 feet, as well as a Convective SIGMET regarding embedded thunderstorms over southern Mississippi. During the cruise phase of the flight at 24,000 feet, the aircraft encountered heavy rain and moderate to severe turbulence. Following this encounter, the aircraft entered a descending right turn, dropping from 24,000 feet to 3,100 feet in approximately two minutes and ten seconds, at which point radar contact was lost.
The wreckage was located 8 hours and 26 minutes after the incident. The debris field was situated between 1.31 and 1.53 miles northwest of Arlington, Alabama.
Findings
Investigations of airframe components by the NTSB Materials laboratory determined that all structural failures were the result of overstress fracturing. There was no evidence of fatigue damage or pre-existing structural issues. The examination concluded that the aircraft's design limits had been exceeded. While the Pilot's Operating Handbook specifies a maximum structural cruising speed of 173 knots indicated airspeed (170 knots calibrated), the co-pilot's airspeed indicator at the crash site showed a calibrated airspeed of 180 knots. Additionally, the aircraft was operating significantly above the design maneuvering speed of 135 knots indicated airspeed (133 knots calibrated).