On November 7, 1997, a Cessna 421A (registration N2957Q) was involved in an aviation accident near Tomahawk, WI. Investigators recorded the probable cause as: the elevator trim tab bolt backed out, allowing the trim tab to flutter, and destroy the elevator. The factors involved were improper annual inspection by the maintenance personnel, and the inadequate aircraft preflight done by the pilot. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot reported a loud bang and rapid control yoke vibration during climb at 11,000 feet. Landing was uneventful. Examination found substantial damage to the right elevator and trim tab, with a missing rear trim tab linkage bolt and an undersized cotter pin in the forward linkage.
Incident
During climb out at 11,000 feet, with a rate of climb of 700 feet per minute and the autopilot engaged, the pilot heard a loud bang and experienced a rapid vibration in the control yoke. The pilot reported that pitch trim was not available. The pilot checked the engines for proper operation. The flight landed without further incident.
Examination Findings
Examination of the aircraft revealed substantial damage to the right elevator and trim tab. The rear trim tab linkage bolt was missing. There was little damage to the yoke or trim tab bushing. Paint transfer marks were found on the trim tab from the elevator. An undersized cotter pin was found in the forward linkage bolt.