On June 20, 2002, at 1930 pacific daylight time, a Cessna 337C, twin-engine airplane, N2671S, was destroyed during a forced landing following a loss of engine power to both engines while on approach to Big Bear City Airport (L35), Big Bear City, California. The airline transport rated pilot, sole occupant of the airplane, was not injured. The airplane was operated by the U. S. Department of Agriculture (USDA) Forest Service Pacific Southwest Region (Region 5) for public use fire fighting missions, and registered to Aero Haven Inc., of Big Bear City. Visual meteorological conditions prevailed, and a flight plan was not filed. The airplane departed San Bernardino, California, at 1900 and was destined for Big Bear City Airport. According to the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2), the pilot reported that during the turn from downwind to base for runway 26, both engines lost total power. The pilot activated both auxiliary electric boost pumps with no change in power noted. Unable to reach the runway, the pilot elected to execute a forced landing to a residential road. After a hard landing to a road, the airplane impacted a tree and a fence. Subsequently, the airplane was destroyed by an ensuing fire. The pilot reported that the airplane contained approximately 40-60 gallons of fuel prior to departure. The 4000-hour pilot had accumulated a total of 46 flight hours in the aircraft make and model. In an interview with the pilot conducted by a representative of the USDA Forest Service, the pilot reported that he placed both fuel selectors in the "AUXILIARY" position approximately 5 minutes prior to landing. While in the traffic pattern, both engines lost total power. After the loss of engine power, the pilot placed both electric fuel pumps in the "LOW" position, with no change in power noted. On June 21, 2002, the airplane, which was recovered to a hangar at L35, was examined by an FAA inspector, representatives from the USDA Forest Service, and a Cessna representative. According to the Forest Service representative, the amount of fuel in the fuel tanks at the accident site could not be determined; however, fuel samples were obtained from all four fuel tanks with no anomalies noted. Due to extensive fire and heat damage, fuel selector handle positions were not obtained. Fuel selector valve positions revealed that the left valve was found in the "AUXILIARY" position, and the right valve was found between the "MAIN" and "OFF" position. In the forward engine, fuel was present in the pressure fuel line between the engine-driven fuel pump and mixture control, and on the demand side of the engine driven fuel pump. In the aft engine, fuel was not present on the pressure or demand side of the engine driven fuel pump. According to the Cessna 337 pilot's operating handbook (POH), the total capacity for each main fuel tank was 46.4 gallons, and the total capacity for each auxiliary tank was 19.0 gallons. The auxiliary fuel pumps are controlled by switches, and the switches are labeled "LEFT MAIN" and "RIGHT MAIN", and their positions are "HI", "LOW", and "OFF". The "LOW" position operates the pumps at low speed, providing sufficient fuel for priming and starting. The "HI" position operates the pumps at high speed, supplying the sufficient to maintain normal power in the event of engine-driven fuel pump failure. In addition, the "HI" position can be used for vapor elimination in flight. The POH "Before Landing" checklist requires the fuel selectors to be in the following positions: Front Engine - "LEFT MAIN"; Rear Engine - "RIGHT MAIN". The POH "Engine-Out During Flight" checklist requires the fuel selectors to be in the main tank positions, and the pilot to "turn its auxiliary fuel pump on 'HI' until fuel flow is restored." In addition, the POH states that "if the auxiliary tanks are to be used, select fuel from the main tank for 60 minutes prior to switching to auxiliary tanks. This is necessary to provide space in the main tanks for the returned auxiliary fuel and vapor. If sufficient space is not available in the main tanks for this returned fuel, the main tanks may overflow through the vent line. When operating from the auxiliary fuel tanks, the tanks will run dry sooner and endurance will be less than may be anticipated since part of the fuel is being diverted back to the main tanks instead of being consumed by the engines."