What happened
During the takeoff phase of a cross-country personal flight, the pilot experienced significant nose-down control forces while the aircraft was accelerating. Despite verifying that the autopilot was disengaged and attempting to use manual trim to counteract the forces, the pilot found the aircraft increasingly difficult to manage and struggled to maintain altitude. The flight ended in an emergency landing, which resulted in substantial damage to the airframe.
Findings
Post-accident inspections of the aircraft revealed that the elevator trim pushrod assembly had disconnected from the elevator trim tab actuator. The end of the pushrod assembly was found wedged against the main spar of the elevator. Although the cockpit trim indicator showed a nose-up position, the actual trim tab was deflected 24 degrees trailing edge up, a position far exceeding the maximum nose-down limit of 6 degrees.
Investigators discovered a damaged, drilled bolt within the right elevator, but the necessary washer, castellated nut, and cotter pin were missing. The investigation noted that the aircraft had recently undergone an annual inspection and a paint job, which involved the removal of the right elevator. During this period, the aircraft was subject to Airworthiness Directives 2016-07-24 and 2016-17-08, both of which mandated the installation of new hardware at the pushrod ends to prevent trim jamming.
While the repair station owner stated the pushrod was not disconnected, photographic evidence suggested otherwise. Crucially, the improperly secured hardware was not replaced as required by the ADs during the maintenance period. It is believed that the failure to use the mandated hardware and the failure to properly secure the assembly allowed the hardware to separate in flight, causing the pushrod to jam the elevator trim tab in an extreme nose-down position.