What happened
While cruising at 7,500 feet en route to his intended destination, the pilot began a gradual descent that lasted approximately 10 minutes. During this descent, the pilot realized the engine had lost power. In an attempt to restore power, the pilot switched fuel tanks, applied carburetor heat for roughly 20 seconds, and manipulated the throttle.
When these actions failed to restore engine power, the pilot searched for a suitable location to perform a power-off forced landing. Due to the lack of smooth terrain in the vicinity, the pilot slowed the aircraft and transitioned into a landing attitude over forested terrain. During the landing sequence, the aircraft collided with several trees.
The investigation
A post-accident inspection of the aircraft revealed that the wire from the carburetor heat control was no longer attached to the bolt in the fitting on the carburetor heat box actuation lever. While the wire had detached from the hole in the bolt, the crush washer, castle nut, and cotter pin remained attached to the bolt. Additionally, the carburetor heat control wire housing was found to be disconnected from its mounting point.
Findings
The pilot reported that the carburetor heat was tested during the pre-takeoff check, noting a significant drop in RPM when the carburetor heat was actuated.