Accident Narrative
After departing with a glider in tow, the pilot initiated a climb to reach sufficient altitude for the glider to release from the tow line. When the airplane reached approximately 1,000 feet above ground level (agl), the engine abruptly lost power. The glider promptly released, and the pilot maneuvered the airplane toward a road for a forced landing.
During the landing roll, the left wing impacted a sign located on the side of the road, causing the airplane to ground loop. The impact crushed the left wing.
Post-Accident Examination
Investigators examined the fuel system after the accident. They drained several ounces of fuel from the gascolator and less than a pint of fuel from the carburetor; no anomalies were noted in the fuel system. The intact fuel tank contained no fuel, and there was no evidence of in-flight fuel leakage from the fuel strainer or tank.
The engine was started without difficulty and operated normally at several different power settings.
Fuel Consumption and Pilot Reports
The accident flight lasted approximately 30 minutes. According to the manufacturer, the engine consumes about 23 gallons of fuel per hour at maximum power (2,575 rpm) and 19 gallons per hour at 2,500 rpm. Using the 19-gallon-per-hour rate, the 30-minute flight would have consumed about 9.5 gallons of fuel.
The pilot reported that prior to the last departure, he believed the airplane had an estimated 10 gallons of fuel on board, but noted that the fuel gauge was unreliable. The airplane had flown 1.4 hours since the last refueling.