Accident Overview
The airplane impacted mountainous terrain in an extreme nose-down attitude after departing from controlled flight. The flight's purpose was to check weather conditions for passenger tour flights that day. About 20 minutes before the accident, the pilot reported the ceiling at 6,500 feet mean sea level (msl). Radar data showed that after this report, the airplane continued eastbound, then returned westbound at about 6,000 feet msl. It entered a series of altitude fluctuations approximately 1 mile west of a ridge that was the accident location. The airplane descended at 4,000 feet per minute while turning northbound, then climbed at 3,900 feet per minute while traveling eastbound, before disappearing from radar. Impact occurred on the eastern side of the ridge. No monitored distress calls or known witnesses were reported.
Preaccident Events
Prior to the accident, there were reports of vibrations during flight on this aircraft, though many went unreported to maintenance personnel. The day before the accident (and the flight prior), a pilot experienced a vibration during flight with passengers but did not report it to maintenance because it was logged improperly in the operator's maintenance tracking system. No corrective actions were taken.
Postaccident Examination
During postaccident examinations, no portions of the right elevator and trim tab were found in the wreckage or at the accident site. The bracket attachment to the right elevator was found loose within the wreckage and was torsionally twisted counterclockwise (aft). Ground and aerial searches based on a trajectory study failed to locate the missing parts. The aircraft was equipped with a foam-cored elevator trim tab installed during manufacture.
Maintenance and Regulatory History
A service difficulty report (SDR) query revealed 47 reports on elevator trim tab corrosion, many including reports of vibrations during flight. On January 20, 2005, the Federal Aviation Administration (FAA) issued Special Airworthiness Information Bulletin (SAIB) CE-05-27, addressing potential problems with foam-filled elevator trim tabs in the accident make/model airplane and Cessna 206 and 210 series airplanes. The SAIB noted that foam-filled elevator trim tabs manufactured until 1985 were reported to have corrosion between the tab and the foam, and when the skin becomes thin enough, the actuator can pull fasteners through the skin and disconnect, leading to flutter. Some reports indicated prior instances of vibrations in the tail section and portions of the elevator tearing away with the trim tab. Earlier, on April 5, 1985, Cessna Aircraft Company issued Service Bulletin (SB) SEB85-7 addressing elevator and trim tab inspection due to corrosion from moisture trapped in foam-cored trim tabs. A review of the airplane's logbooks showed that the SB was not complied with, nor was the operator required to do so based on FAA-approved maintenance specifications.