Accident Sequence
While in cruise flight, the pilot found that throttle response was not possible and engine revolutions per minute decreased to near idle. The pilot initiated a descent for a forced landing with the landing gear extended. Later, the pilot stated that he could not recall the last several thousand feet of the descent. The airplane subsequently collided with trees and then the ground.
Postaccident Examination
A postaccident examination of the airplane revealed that a castellated nut, which secures a lever onto the throttle plate shaft, was loose by 10.5 turns of the six-sided nut. No cotter pin was found in place. This condition would prevent movement of the throttle plate shaft when the throttle control was moved. The engine was removed from the airplane and placed in a test cell, where it was found to operate normally.
Maintenance History
Following a collapse of the nose landing gear in August 1998, the engine and fuel control valve were overhauled. After the engine overhaul, the engine was test run. The air throttle assembly was then removed for shipping, the lever was loosened, and the engine and boxed air throttle assembly were shipped to the location where the airplane was being repaired. The air throttle assembly was installed on the engine, which was then installed into the airplane. The engine was subsequently run, and no engine-related discrepancies were noted.