Flight Details
The pilot departed after noting that the left fuel tank gauge indicated less than 1/4 tank and the right fuel tank gauge indicated 1/4 tank of fuel. The pilot did not visually verify the fuel quantity in the tanks and departed using the right tank. The airplane had accumulated about 5 1/2 hours since its last refueling. The pilot planned to obtain fuel from another airport in his city but a family member requested a ride from a nearby airport, prompting the decision to refuel there instead.
Engine Power Loss
During the flight, the pilot climbed the airplane to 5,500 feet mean sea level and set the manifold pressure and rpm at 25 inches and 2,500 rpm, respectively. He then leaned the mixture to 30 degrees lean of peak. About 20 minutes into the flight, the pilot felt a drop in power and noticed a fluctuating fuel flow indication, while the right gauge still showed almost 1/4 tank. He switched to the left fuel tank, which restored power and stabilized fuel flow.
Forced Landing
While approaching to land at the nearest airport, the pilot extended the gear and set the flaps to the approach setting. The engine then began to lose power again with fluctuating fuel flow. He applied full rich mixture, full forward on the throttle and propeller, and switched the fuel selector to the right tank, pitching for best glide speed. The airplane was about 1,500 feet above ground level and nearing the approach end of the runway. The pilot elected to perform a 360-degree turn to dissipate altitude. After 270 degrees, he assessed the airplane was too low to land on the runway. After evaluating other landing options, he chose to land in the river, raised the gear, and slowed the airplane to 80 miles per hour. Upon landing, the pilot egressed the airplane and swam to shore. Performance calculations indicated the usable fuel level would have been nearly depleted based on flight profiles and times since last refueling.