Accident Overview
A student pilot with 51 hours of flight time entered the traffic pattern and discovered on downwind that the engine RPM was fixed at 2,000. The pilot continued the approach to a 5,419-foot long runway but made no attempt to shut down the engine once the runway was assured. After touchdown, the aircraft could not be stopped. The pilot then attempted a go-around maneuver followed by a re-landing in a soft field. During this second landing, the pilot again made no attempt to shut down the engine once the landing field was assured.
Aircraft Damage
While the aircraft was moving across the soft field, the nose-gear assembly collapsed due to overload, and the aircraft nosed over.
Post-Crash Examination
A post-crash examination revealed that the throttle cable had become disconnected at the throttle-to-carburetor adapter plate on the carburetor throttle arm. The bearing end of the throttle rod, along with one of its retaining nuts, was absent. The bolt that passes through both the rod-end bearing and the carburetor adapter plate was also missing. Additionally, all three washers on this bolt, as well as its associated nut and cotter key, were absent.
Maintenance History
Examination of the aircraft's airframe log showed that the owner, a certificated mechanic, had removed and replaced the throttle cable 5.4 hours prior to the disconnect.