What happened
On February 3, 2019, a Cessna 414, registration N414RS, departed Fullerton Municipal Airport (FUL) for a personal cross-country flight. While the weather at departure was visual, the aircraft encountered instrument meteorological conditions (IMC) involving rain, precipitation, and a microburst while climbing. During takeoff clearance, the tower controller warned the pilot of deteriorating weather approximately 4 miles east of the airport.
Radar data indicated that approximately 5.5 minutes after takeoff, the aircraft reached 7,800 feet above ground level before entering a rapid, descending right turn. Data from the aircraft's Appareo Stratus 2S unit showed that during the final 15 seconds of flight, the aircraft's attitude became erratic, with pitch angles fluctuating between 45° nose-down and 75° nose-up, and bank angles swinging between 170° left and 150° right. The aircraft descended from 5,500 feet to 500 feet during this period before impacting the ground.
Witnesses reported seeing the aircraft exit the clouds at a high descent rate, noting that parts of the airplane began to separate in mid-air. One witness observed the left horizontal stabilizer and the remaining empennage separate, followed by the left wing shearing off near the engine.
The investigation
Investigators examined a debris field spanning approximately 1,000 feet by 800 feet. The wreckage of the left engine, left propeller, and fuselage was found in the northern section of the debris, while the right engine and propeller impacted an asphalt road and a nearby yard.
Structural analysis of the wings and horizontal stabilizer revealed that the components separated due to overstress caused by excessive aerodynamic loads. The left and right wing spars exhibited fractures with a dull, grainy appearance consistent with overstress separation. The horizontal stabilizer and elevators also separated from the empennage due to structural failure.
Examination of the engines revealed no mechanical malfunctions or failures that would have prevented normal operation. While toxicology tests detected THC and diphenhydramine in the pilot's system, investigators noted that postmortem redistribution could affect these levels and concluded it was unlikely these substances contributed to the accident.