On July 23, 1993, at approximately 2155 Pacific daylight time (PDT), a Cessna 177, N30170 impacted trees during an attempted forced landing near Troutdale, Oregon. The FAA certificated commercial pilot and two of his passengers received minor injuries, the third passenger received serious injuries, and the aircraft sustained substantial damage. The combination VFR/IFR personal pleasure flight, which departed Petaluma Municipal Airport, Petaluma, California at about 1710 PDT, flew most of the route without a filed flight plan, but picked up an IFR clearance as it neared the destination airport. The accident occurred in visual meteorological conditions, and there was no report of an ELT activation. The pilot, who departed the original destination with the intention of a non-stop flight to the Troutdale Airport, climbed to a cruise altitude of 9,500 feet, but then found it necessary to divert into Willows-Glenn County Airport for a passenger "bathroom stop." After this stop, the pilot departed the Glenn County Airport, and climbed a second time to a cruise altitude of 9,500 feet. The flight continued VFR until it was near the Troutdale area, where the pilot received an IFR descent. During the descent, the pilot visually located the airport, canceled IFR, and contacted the Portland Troutdale Tower for landing. According to the pilot, the total flight time to that point was about four hours and seventeen minutes. Approximately two minutes after contacting the tower, the pilot reported that he had lost engine power. He attempted a forced landing in a small field, but impacted trees near the edge of the field. According to the FAA Inspector who responded to the accident, the pilot, who mentioned that he had experienced headwinds of about 20 knots over the entire route, said that both fuel gauges were reading empty prior to the engine losing power. When asked why he tried to continue on to Troutdale with the fuel gauges indicating as they were, the pilot said he had made the trip to Troutdale once before in this aircraft, and based upon that, and other trips in the same aircraft, he figured he still had enough fuel to reach his destination. After the accident an FAA Operations Inspector completed a flight plan and fuel burn summary for this flight using the reported weather and the performance data for a 180 horsepower engine, to which this aircraft had been converted from its original 150 horsepower powerplant. That summary, which was based upon a total flight time of four and three-tenth hours en route, including two starts, two taxis to takeoff, and two climbs to 9,500 feet, showed an expected fuel burn of 47.5 gallons. At the accident site, less than one pint of fuel, out of the 48 usable in this aircraft, was found in the aircraft fuel system.