LAX96LA117

The pilot reported that the aircraft was en route over low rolling foothills when the engine quit. The aircraft firewall and nose gear was damaged during the forced landing on a road. Examination of the aircraft by a A&P mechanic revealed that the fuel system was intact. Only residual fuel was found in the fuel tanks. Following recovery of the aircraft, the engine was started using the airframe systems; it accelerated to power smoothly with normal magneto drops observed. The pilot stated the aircraft is rented full of fuel by the FBO and during the preflight inspection put her fingers in the filler port and felt fuel at a level about 1 inch below the top of the filler neck. The pilot noted that the fuel gages in this aircraft historically read something less than full when the tanks are filled and the gage reading on start of between 3/4 and full seemed normal. Cessna Aircraft reported that the tanks must be filled to the top of the filler neck to obtain a 20 gallon usable fuel level. A fuel level at the bottom of the filler neck equals 18 usable gallons and each inch in fuel level below that is equal to about 2 gallons of fuel. The difference between the takeoff time and the accident is 3 hours 22 minutes according to FAA ATC communication tapes. The Safety Board calculated the expected fuel usage using both the aircraft performance charts in the Cessna POH, and specific fuel flow figures provided by Lycoming for an engine operated at full rich condition. With the stated allowances for engine start, taxi and takeoff, the Safety Board calculated that 28.4 gallons of fuel would be used when the engine was leaned and the aircraft flown according to the manual. In the full rich condition, 33.4 gallons of fuel would be required.

On February 16, 1996, at 1740 hours Pacific standard time, a Cessna 172P, N53115, sustained substantial damage during a forced landing near Raymond, California. The forced landing was precipitated by a total loss of power while in cruise. The aircraft was operated by Royal Aviation of Costa Mesa, California, and was rented by the pilot for a cross-country personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The certificated commercial pilot and three passengers were not injured. The flight originated at Santa Ana, California, on the day of the accident at 1417 as a flight to Mariposa, California.

The pilot reported that the aircraft was en route over low rolling foothills when the engine quit. The aircraft firewall and nose gear was damaged during the forced landing on a road.

Examination of the aircraft by an FAA A&P mechanic revealed that the fuel system was intact. Only residual fuel was found in the fuel tanks. Following recovery of the aircraft to Aircraftsman in Chino, California, the engine was started using the airframe systems. The mechanic who performed the test for the Safety Board reported that engine started on the first attempt and accelerated to power smoothly with normal magneto drops observed.

The aircraft operator was interviewed telephonically on February 20th and reported that the pilot told him that during preflight she reached up and put her fingers in the fuel tank filler necks and felt fuel. The pilot did not visually verify the fuel quantity. The pilot further told the operator that during the preflight inspection and engine start the fuel gages indicated somewhere between 1/2 and full, and the pilot assumed the gages were incorrect.

The pilot was interviewed by telephone on March 7th and reported that the flight was normal following takeoff and climb to 8,500 feet msl until the engine began to sputter. The pilot attempted to correct the engine problem by switching the fuel selector and using carburetor heat but did not obtain a restart. The pilot was questioned about the procedures used to determine the fuel load on the aircraft prior to flight. The pilot stated that the aircraft is normally rented full of fuel by the Fixed Base Operator. During the preflight inspection the pilot put her fingers in the filler port and felt fuel at a level about 1 inch below the top of the filler neck. The pilot further reported that the fuel gages in this aircraft historically read something less than full when the tanks are filled and the gage reading on start of between 3/4 and full seemed normal.

On May 2, 1996, the pilot, through her attorney, wrote a letter to the Safety Board with the stated intent of correcting her verbal statement of March 7th. In the written statement submitted with the letter, the pilot denied that she only reached into the tanks to feel the fuel and stated that she used the steps on the fuselage side to climb up and look inside the tanks. The pilot said she saw the fuel and "double check[ed] it by running my index finger down the filler neck to be sure the fuel level is full up to the filler neck."

Cessna Aircraft was contacted and reported that their delivery files on the aircraft listed that two 21.5 gallon total capacity (20 gallon useable in each) fuel tanks were installed at manufacture. The company further reported that the tanks must be filled to the top of the filler neck to obtain a 20 gallon usable fuel level. A fuel level at the bottom of the filler neck equals 18 usable gallons and each inch in fuel level below that is equal to about 2 gallons of fuel. The company further reported that the fuel tanks in the Cessna 172P have pickup points at both the forward and aft inboard corners.

The aircraft's departure time from the John Wayne Orange County Airport was reported by the Air Traffic Control Tower as 1417 Pacific standard time. The aircraft was in radio contact with Fresno Approach Control at the time of the engine failure. According to the air-to-ground communications tapes, the pilot declared an emergency at 1739 Pacific standard time. The elapsed en route time for the aircraft from takeoff to engine failure was 3 hours 22 minutes.

The Safety Board calculated the expected fuel usage for the accident trip by using both the aircraft performance charts in the Cessna Pilot's Operating Handbook for the Cessna 172P, and, specific fuel flow figures provided by Textron Lycoming for an engine operated at full rich condition. The Cessna performance charts are predicated on a lean mixture condition. The charts used for the calculations are appended to this report. According to Lycoming, the maximum fuel flow that could be put through the engine and still have it run is 12 gallons per hour, and the specific fuel consumption for a full rich condition is 0.47 pounds/hour/horsepower. The following table presents the derived fuel flows in a full rich condition:

% Power Brake Horsepower Specific Fuel Cons. GPH 65 104 0.47 8.2 70 112 0.47 8.8 75 120 0.47 9.5

With the stated allowances in the POH performance charts for engine start, taxi and takeoff, the Safety Board calculated that 28.4 gallons of fuel would be used for the known flight time when the engine was leaned and the aircraft flown according to the manual. In the full rich condition, 33.4 gallons of fuel would be required.