Engine Failure After Carburetor Heat Application Leads to Loss of Control and Impact with Terrain (N9240T)

Accident Sequence

The pilot was descending the airplane into the control zone and had received clearance to enter a right base for runway 15. After applying carburetor heat, the engine quit. The pilot executed a 180-degree turn and descended over an open grass field while attempting to glide to a dirt field. A fence and a railroad track lay between the fields. The airplane struck the fence, rotated approximately 180 degrees, and descended out of control, impacting the terrain near the railroad tracks.

Investigation Findings

The investigation revealed that the main valve for the carburetor heat box had failed and was sucked into the carburetor inlet, blocking air flow and rendering the carburetor inoperative. Further investigation found that portions of the valve assembly had been failing for an unspecified time prior to the accident and that its retaining screws had not been secured properly.