Event Summary
While the airplane was climbing, the pilot reported that he did not have any elevator control. Radar data revealed that the airplane momentarily leveled off at 1,000 feet, then climbed to 2,000 feet before entering a descent. The airplane subsequently impacted a rail car in a railroad yard. The impact occurred in a steep nose-down pitch attitude.
Investigation Findings
Examination of the airplane after the accident revealed that the elevator trim was in a full nose-down position. The elevators were found in a trailing edge down position at impact. Further examination of the elevator trim system provided details on its operation.
Elevator Trim System Details
The elevator trim system was examined to understand its behavior. It was found that the trailing edge of the elevator trim tab moves down for airplane nose-up trim and up for airplane nose-down trim. Additionally, the investigation noted that if elevator movement is restricted, the elevator trim tab can function as a small elevator. In such a scenario, the trim tab would move the airplane opposite to the direction intended by movement of the cockpit elevator trim wheel.