What happened
The aircraft utilized approximately half of the available 8,602-foot runway for its takeoff roll. Shortly after liftoff, while beginning the initial climb over the runway, the airplane pitched nose-down briefly. The pilot transmitted a radio message indicating a problem with the elevator control system, stating that full back pressure was required to maintain nose-up attitude and that he intended to return to the airport for landing. After maneuvering around the airfield, the aircraft pitched approximately 70 to 80 degrees nose-down and dove into terrain located off the approach end of the runway.
The investigation
A physical examination of the wreckage revealed a critical mechanical failure within the elevator trim system. Specifically, the bolt securing the elevator trim tab pushrod to the actuator was missing. This omission allowed the pushrod to become wedged inside the elevator structure, forcing the trim tab into an extreme up position which induced the severe nose-down pitching moment observed during the flight.
Findings
Contributing factors included a recent annual inspection performed just two days and five flight hours prior to the accident. The inspecting mechanic reported that no maintenance was performed on the tab system and expressed certainty that the bolt had been properly safety-wired at that time. Additionally, another pilot who flew the aircraft on the day of the accident reported finding the pushrod secure during his preflight inspection. Performance data from the Pilot's Operating Handbook for the Cessna 402B indicated that the aircraft should have required approximately 1,200 feet for the takeoff ground roll.
missing bolt securing elevator trim tab pushrod