ERA26LA018

The pilot departed on the 130 nautical mile cross country flight, with about 14 gallons of aviation fuel, or 7 gallons per side. After departure, the airplane climbed to a cruising altitude of 2,500 ft mean sea level and proceeded normally. About 50 minutes into the flight, the engine began to run rough with a simultaneous decrease in engine rpm, manifold pressure and fuel pressure. The pilot diverted to a nearby airport and attempted to troubleshoot the rough running engine by advancing the throttle, moving the mixture to full rich and activating the auxiliary fuel pump, which provided brief improvement, before fuel pressure continued to decrease. Unable to maintain level flight, the pilot attempted a forced landing in a field. During the approach, the pilot observed powerlines on short final, and the airplane’s left wing clipped a powerline resulting in a loss of control and a hard landing on rough terrain. The airplane came to rest against a fence and sustained substantial damage to the fuselage and left wing. The pilot reported that he manually dipped the fuel tanks before the flight with a calibrated fuel dipstick; however, he was unable to produce the dipstick or confirm the origin of calibration. In addition, he stated that the engine instruments indicated that he had 27 minutes of fuel remaining at the time, the engine roughness occurred. Postaccident examination of the airplane revealed no preaccident mechanical malfunctions or failures that would have precluded normal operation. The fuel system was intact and undamaged, the engine fuel supply lines were devoid of fuel, and the total fuel recovered from both fuel tanks was 1 quart. Based on the absence of mechanical anomalies, the lack of fuel in the fuel tanks and engine fuel supply lines, the pilot’s inability to provide or substantiate the calibration of the fuel dipstick, and his overreliance on fuel quantity instrumentation, it is likely that pilot departed with an inaccurate assessment of the available fuel, and the resulting loss of engine power was due to fuel exhaustion.