Incident Overview
While at cruise altitude, the airplane's engine experienced a partial loss of power. The pilot reported that he applied carburetor heat and checked the oil temperature and pressure, but the engine did not regain power. Subsequently, the pilot attempted to perform a forced landing in a yard below the airplane's flight path.
Accident Sequence
During the approach to landing, the airplane collided with trees. After the collision, the airplane fell to the ground and came to rest inverted.
Post-Accident Examination
A post-accident examination of the airplane did not reveal any airframe anomalies. The engine was dismantled and examined. Examination of the carburetor revealed that the throttle valve actuating arm, which was fastened to the throttle shaft, was loose. As a result, the arm would not open the throttle valve fully.