Cessna T310Q N301JA accident near Wichita, Kansas

Probable cause

The separation of the attachment hardware connecting the elevator trim tab pushrod to the elevator trim actuator, which resulted in the elevator trim tab jamming in a position outside the limits of normal travel and a subsequent loss of airplane control.

NTSB analysis

The commercial pilot was departing on a personal cross-country flight in the airplane. During initial climb after takeoff, witnesses saw the airplane suddenly pitch down into a rapid descent that continued to ground impact. Postaccident examination revealed that the elevator trim pushrod was attached to the trim tab but not attached to the trim tab actuator. The bolt, nut, and cotter pin securing the elevator trim tab pushrod to the actuator were missing and not recovered. Examinations of the elevator and the pushrod revealed that the pushrod became jammed aft of the forward elevator spar creating an abnormally large trim tab up (nose down) condition.

Measurements taken from an exemplar airplane of the same make and model as the accident airplane indicated that the elevator trim tab deflection with the pushrod jammed aft of the forward elevator spar would be over three times the normal maximum trailing-edge-up deflection. The airplane nose-down pitching moment at this increased deflection would create a forward force on the control yoke that a pilot would likely not be able to overcome.

Following the accident, the manufacturer issued a service bulletin that required the hardware securing the elevator trim pushrod be replaced and specified the hardware to be used. Subsequently, the Federal Aviation Administration issued an airworthiness directive that required compliance with the service bulletin.

Although the pilot's toxicology results were positive for ethanol in muscle tissue, when detected only in the muscle tissue, ethanol is likely from a source other than ingestion. No medications or illicit drugs were found that could pose hazards to flight safety.

Text from the NTSB. Open the NTSB docket for CEN15FA425 for the full record.