The pilot was on a cross-country flight and about 1 hour and 20 minutes into the flight, while in cruise flight at an altitude of about 2,400 ft msl, the airplane’s engine began to vary in rpm for several seconds before it reduced to idle power. The pilot attempted to troubleshoot the problem by applying carburetor heat and attempting to restart the engine, but was unsuccessful, and he subsequently performed a forced landing to a field. The airplane’s left wing was substantially damaged during the forced landing. A post-accident examination of the airplane revealed that both of the airplane’s fuel tanks were intact with no evidence of a breach. Less than one gallon of fuel was recovered from both tanks. The right fuel quantity indicating gauge in the cockpit showed an empty indication when electrical power was applied, while the left fuel quantity indicating gauge indicated between ¼ and ½ tank. While a trace amount of fuel was present in the airplane’s unobstructed fuel lines, the gascolator was absent of fuel. Examination of the engine revealed no evidence of any preimpact mechanical malfunction or failure, and the engine was successfully test run when it was plumbed to an external fuel source. Following the accident, the pilot stated he believed that the airplane contained 18 or 19 gallons of fuel before he departed on the accident flight. He also stated that during his preflight inspection, the center sump drain stuck open for between 4 and 5 seconds and required repeated cycling in order to get it to close. The airplane was equipped with two fuel tanks that could be filled with a combined total of 22.5 usable gallons of fuel. The pilot stated, and fueling records confirmed that the airplane was serviced with 18 gallons of fuel two days before the accident. The pilot described that the fuel was filled in each tank to the “tabs.” A review of ADS-B data provided by the Federal Aviation Administration revealed that the airplane was subsequently flown for about 2 hours after the fueling. Based on this information, it is unlikely that the airplane contained the 18 gallons of fuel the pilot estimated were onboard when he departed on the accident flight. Given the uncertain nature of the airplane’s actual fuel state when the pilot departed on the accident flight, combined with the lack of fuel found onboard the airplane at the accident site, as well as the successful postaccident test run of the engine, it is most likely that the loss of engine power the pilot experienced during the accident flight was a result of fuel exhaustion.