WENATCHEE, WA, USA
N51816
CESSNA 402B
THE ELEVATOR TRIM JAMMED SHORTLY AFTER TAKEOFF. THE PILOT RETURNED TO THE DEPARTURE AIRPORT, WHILE HOLDING ABOUT 150 POUNDS OF BACK PRESSURE ON THE CONTROL WHEEL. WHEN HE MOVED ONE HAND TO THE THROTTLES TO REDUCE THE POWER, HE WAS UNABLE TO HOLD THE NOSE UP, AND THE AIRCRAFT IMPACTED TERRAIN ABOUT 300 FEET SHORT OF THE APPROACH END OF THE RUNWAY. INVESTIGATION REVEALED THAT COMPANY MAINTENANCE PERSONNEL HAD FAILED TO INSTALL A COTTER KEY, AND THE TRIM TAB PUSH ROD ATTACHMENT BOLT, NUT, AND COTTER KEY WERE MISSING.
On July 28, 1995, approximately 2100 Pacific daylight time, a Cessna 402B, N51816, impacted the terrain while attempting an emergency landing at Pangborn Memorial Airport, Wenatchee, Washington. The commercial pilot, who was the sole occupant, was not injured, but the aircraft sustained substantial damage. The Part 135 cargo flight, which had just departed Pangborn Airport for Boeing Field, Seattle, Washington, was being operated in visual meteorological conditions at the time of the accident. The pilot had filed an IFR flight plan, and there was no report of an ELT activation. According to the operator, the elevator trim actuator rod failed during the takeoff sequence when the aircraft was about 100 feet above ground level. The rod then became jammed in a manner that resulted in a nose-down trim greater than the normal full nose-down position. The pilot therefore immediately attempted an emergency landing on the runway from which he had just departed. During this attempted landing, the aircraft impacted the terrain about 300 feet short of the runway threshold. The pilot stated that he estimated about 150 pounds down force on the yoke. He let go of the yoke with one hand to retard the throttles, and was unable to keep the aircraft from impacting short of the runway threshold. FAA investigators found that the elevator trim tab was in the extreme nose-down trim position, while the cockpit trim wheel was found in the extreme nose-up trim position. The trim was tested with no effect. Inspectors then noted that the attaching bolt, nut, and cotter key for the trim-tab push rod to the trim-tab actuator-assembly was missing. The disconnected end of the trim- tab push rod was wedged behind the elevator spar, forcing the trim tab into its extreme nose-down trim position. Maintenance logs showed that the right elevator had been replaced on July 15, 1995, 24.9 flight hours prior to the accident. The mechanic performing the repair stated that he had used the old hardware to perform the installation, but he was certain he had installed the cotter key. The operator provided an incomplete portion of the NTSB form 6120.1/2, which is attached.
IMPROPER INSTALLATION (FAILURE TO INSTALL COTTER KEY) BY COMPANY MAINTENANCE PERSONNEL.
Source: NTSB Aviation Accident Database
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