Incident Summary
An aircraft suffered an engine stoppage while within 10 miles of its destination airport. The pilot reported that the engine sputtered and stopped while the fuel valve was in the 'BOTH' position. After the stoppage, the pilot stated that the fuel gauges indicated one quarter full in each tank.
Pilot Actions
In response to the engine sputtering, the pilot pulled on carburetor heat and switched fuel tanks. Subsequently, the pilot focused on executing a forced landing. During the landing, the nose gear became mired in soft terrain, and the aircraft nosed over.
Post-Accident Examination
At the accident site, the fuel valve was found in the right tank position. Examination revealed that the left tank was empty, while the right tank contained 15 gallons of fuel. Fuel was present in all lines, the main fuel filter, and the carburetor. Despite these findings, no reason was found for the powerplant stoppage.