Accident Summary
A pilot experienced an unexpected engine power loss while performing a go-around. The aircraft subsequently entered a series of rolls and collided with terrain.
Pilot Report
The pilot stated that after applying full throttle and engaging the carburetor heat during the go-around, the engine did not respond normally. The pilot described the sensation as "a brake had been applied to the engine" and noted that it did not pick up RPM as expected. The aircraft began rolling to the right, prompting the pilot to apply left aileron and left rudder in an attempt to level the wings. However, the aircraft then made an abrupt roll to the left and impacted the ground.
Engine and Carburetor Inspection
A post-accident inspection of the carburetor revealed that the horseshoe washer, identified as the Mixture Control Valve Head, had become detached from the Mixture Control Metering Valve and was found lying in the bottom of the carburetor bowl. When the washer was manually placed back onto the metering valve, it was loose. Additionally, the inspection found that the pump plunger assembly, float valve seat, and Mixture Control Metering Valve exhibited wear. The carburetor airbox gasket was noted to have a smaller diameter than the carburetor air intake.
Engine Test
The engine was removed and placed on a test stand fitted with an operable carburetor. During testing, the engine ran at idle power and at 2,300 RPM.