N66AS

The pilot checked weather and requested that the airplane be serviced with full fuel before the cross-country flight. Fuel receipts show the airplane was serviced with 34.5 gallons. The airplane's fuel capacity was 50 gallons. He performed a preflight inspection of the airplane to include confirming that its fuel tanks were full. About an hour after takeoff, the pilot checked the fuel gages, which indicated that less than 10 gallons was used. About two hours after takeoff, they indicated that less than 20 gallons was used. About three hours after takeoff, the gages indicated that 28 gallons was used. The pilot indicated that he would have stopped for fuel if there were less than 17 gallons of fuel remaining at that point in the flight. The pilot continued the flight and estimated the airplane had 12 gallons of fuel remaining when it was 17 miles from the destination. He reported that the left tank fuel pressure decreased with 2.5 gallons showing on the gauge prompting a switch to the right tank, which showed 6 gallons remaining. About nine miles from the destination and 1,000 feet above the ground, the airplane flew through brief moderate turbulence. The right fuel tank level dropped to zero fuel within a minute along with a drop in fuel pressure. The pilot started to switch from tank to tank trying to use all the fuel in the tanks. When the airplane lost engine power, he selected a field and performed a forced landing about four hours and ten minutes after departure. The airplane sustained substantial fuselage damage during the forced landing. No fuel leaks were found during the airplane recovery. The left fuel tank contained about one cup of fuel and the right tank did not contain any fuel. A flight-planning chart in the airplane's manual indicated that the airplane should burn ten gallons per hour with a lean mixture. According to the Federal Aviation Administration publication, The Pilot's Handbook of Aeronautical Knowledge, "aircraft certification rules require accuracy in fuel gauges only when they read 'empty.' Any reading other than 'empty' should be verified. Do not depend solely on the accuracy of the fuel quantity gauges."