Preflight and First Flight
During the engine run-up before the first flight of the day, the pilot noted no resistance on the control knob when checking the carburetor heat operation. The engine RPM returned to normal with a slightly sluggish response. The first flight proceeded without further issue.
Second Flight Incident
During the second flight's engine run-up, applying carburetor heat caused the RPM needle to wiggle down by 50 RPM before returning to the set value. The takeoff appeared normal until reaching about 200 feet above the runway, when the aircraft felt "soggy." The pilot raised the landing gear to reduce drag, but the engine still did not seem to be producing power. He then extended the landing gear and decided to land in a field off the end of the runway.
Landing and Damage
During the landing, the landing gear, which was not locked down, collapsed. The left wing contacted a runway end identifier light, resulting in substantial damage.
Post-Accident Inspection
Post-accident examination of the airplane and engine revealed that the carburetor heat bracket between the valve shaft and the cable was fractured and missing. The carburetor heat valve was found in the open position.