Throttle Plate Separation Causes Power Loss and Forced Landing (N9064M)

Event Description

While descending, the pilot pulled the throttle to reduce engine power but observed no response. A second attempt to reduce power resulted in the manifold pressure gauge indicating the engine power dropped to idle. However, when the pilot tried to push the throttle forward, it was impossible to move. Subsequently, the pilot executed a forced landing. During the landing roll, the aircraft struck a fence and a tree, resulting in damage.

Investigation Findings

Examination of the fuel servo revealed that the throttle plate had become detached from the throttle shaft. This separation occurred because the attachment screws were not properly secured during an overhaul of the component. The condition led to restricted airflow into the induction system, which in turn caused the loss of engine power. No other anomalies were reported in the fuel servo or related systems.