What happened
The aircraft departed from an airport near Sutter Creek, California, bound for San Jose, California. Upon arrival at the destination, the engine lost power approximately 2.25 miles from the airport. The pilot was unable to restart the engine and initiated a forced landing. During this maneuver, the aircraft struck a berm, resulting in damage to the airframe.
The investigation
Post-acc examination of the fuel tanks revealed that less than three gallons of fuel remained. The total fuel capacity of the aircraft is 26 gallons, with 22.5 gallons considered usable. The flight duration since the last refueling was four hours. According to the owner's manual, the aircraft's endurance at 4,000 feet with 75% power is exactly four hours. The manual further notes that this value can vary by 10 percent or more due to variables such as carburetor metering characteristics, engine and propeller condition, and atmospheric conditions.
Findings
The pilot reported visually checking the fuel before departure from Sutter Creek, stating the tanks were nearly full. However, no additional fuel was added prior to the return flight. The left fuel gauge indicated nearly one-quarter full, while the right gauge showed one-eighth full at the time of engine failure. The discrepancy between the visual check and the actual remaining fuel suggests a miscalculation of consumption or gauge inaccuracy. Fuel exhaustion was the primary factor leading to the loss of power.
Safety message
Pilots should account for potential variations in aircraft endurance due to operational variables. Relying solely on time-based endurance calculations without considering real-time fuel state and gauge readings can lead to critical shortages.