On March 31, 1996, at 1554 hours Pacific standard time, a Cessna 150L, N5266Q, nosed over in soft marshy terrain following a forced landing near Sacramento, California. The forced landing was precipitated by a total loss of power during cruise. The aircraft was operated by American Aero Flying Club of Sacramento and was rented by the student pilot for a solo cross-country flight. Visual meteorological conditions prevailed at the time and a VFR flight plan was filed. The aircraft incurred substantial damage. The student pilot, the sole occupant, sustained serious injuries. The flight originated from Notomas airport in Sacramento on the day of the accident at 1115, and made en route stops at Redding, Willows, and Davis/Woodland, California. According to controllers at the Sacramento TRACON, the pilot called Mayday while the aircraft was descending through 2,000 feet. He reported to the controller that he was losing power and going down. The aircraft landed in a marsh area and nosed over after the landing gear encountered soft mud. The operator reported that according to the recording hour meter onboard the aircraft it had flown 4.6 hours since departing the Notomas airport. Fueling records at Redding disclosed that 9.6 gallons of 100LL were pumped into the aircraft at 1335. The pilot stated that after the fueling he checked the tanks and found them to be completely full. Air traffic control tower tapes at Redding disclosed that the aircraft departed at 1345. The times of arrival and departure from Willows and Davis/Woodland are unknown. FAA inspectors responded to the accident site, and during the aircraft recovery operation performed a preliminary examination of the aircraft. The fuel system was intact with no ruptures or breaks to any tank or line. No evidence of fuel spill was noted under the airplane, however, the FAA airworthiness inspector stated that he could detect an odor of fuel. Just over 3 pints of fuel was drained from the fuel system during disassembly of the aircraft for movement to a storage facility. The responding FAA inspectors performed an analysis of fuel required for the flight from Redding to Sacramento and reported that the aircraft should have had sufficient fuel to complete the trip. Following recovery of the aircraft, the FAA inspectors supervised a test run of the engine utilizing the existing airframe plumbing and electrical systems. According to the FAA inspector's report, the engine started and operated satisfactorily. A detailed examination of the aircraft disclosed no airworthiness discrepancies. The closest official weather observation station to the accident site is the Sacramento Executive Airport, which is 5 miles east. At 1554, the local aviation surface observation was reporting in part a temperature of 74 and a dew point of 47 degrees Fahrenheit. According to a carburetor icing probability chart, the temperature/dew point spread falls in a region on the chart annotated "moderate icing --- cruise power or serious icing --- glide power."