Accident Details
A pilot was conducting night proficiency takeoffs and landings in a Cessna 182E. The first two circuits were normal. After the third takeoff, as the airplane lifted off the runway, the pilot's seat slid all the way to the rear stops. The pilot responded by pulling the throttle back to prevent further climb, and the airplane landed hard on the runway.
Examination
A subsequent examination of the seat rails, seat rail pinholes, seat adjustment pin, and coil spring was performed by a manufacturer's representative and a Federal Aviation Administration (FAA) inspector. No anomalies were found. Airworthiness Directive 87-20-03 R2 had been complied with, and an annual inspection had been completed about seven months earlier.
Findings
Another FAA inspector, of similar size to the pilot, tested the seat locking mechanisms while seated. When the seat locking pin was secured in any of the pinholes, the seat could not be moved. However, when the pin was not securely locked into a hole, even a small weight shift caused the seat to slide backwards to the rear stops without the pin engaging any of the pinholes.