ATL97LA028

Because the flight was taking longer than expected, the pilot elected to divert for fuel. While being vectored for an approach, the engine quit. During the ensuing forced landing, the airplane collided with trees and the ground. There was no evidence of a loss of fuel during the flight nor at the accident site, and the engine was operated following the accident. However, testing of the fuel injector servo revealed that its flow exceeded the maximum limit. The pilot stated he was using 11 gallons per hour for fuel usage planning. Using the power setting and altitude the pilot reported he used during the flight, the engine manufacturers operating manual indicated that the fuel usage would be between 11.3 and 13 gallons per hour (gph), depending on the mixture setting. Based on the elapsed time of the flight, the usable fuel supply in the airplane, and the excessive fuel servo flow, at 11.3 gph, about six gallons of fuel would have remained in the airplane. At 13 gph, more fuel than the usable capacity would have been needed. The fuel usage, therefore, exceeded the pilot's planned usage, discounting the servo's excessive flow rate.

On December 26, 1996, about 1248 eastern standard time, a Mooney M20F, N737JC, collided with trees and the ground about two miles from the approach end of runway 7L at Daytona Beach, Florida. The airplane was operated by the pilot under the provisions of Title 14 CFR Part 91, and visual flight rules. An instrument flight plan had been filed for the personal flight. There were no injuries to the private pilot, who was instrument rated, nor the passenger, and the airplane was substantially damaged. Origination of the flight was Elizabeth City, North Carolina, about 0822, on the same day.

According to air traffic personnel, the flight was originally destined for Melbourne, Florida. While the flight was in contact with Jacksonville Air Route Traffic Control Center, the destination was changed to Daytona Beach, Florida. The pilot reported critical fuel when about seven miles from Daytona Beach International Airport. Subsequently, about two miles from the airport, the pilot reported that the airplane would not reach the runway.

The FAA inspector who visited the accident site reported no evidence of siphoned fuel, no evidence of fuel on the ground, and no a fuel odor.

From the departure time until the pilot reported a loss of engine power, 4.5 hours elapsed. According to a record of telephone conversation between the FAA inspector and the airplane fueler, the fuel tanks were filled to their capacity of 64 usable gallons. The pilot reported that he used 11 gallons per hour to calculate the fuel usage, which was consistent with the owners manual for the 1967 airplane. At 11 gallons per hour and 4.5 hours elapsed flight time the total fuel usage would be 49.5 gallons. Fuel used for taxi, run-up, and takeoff was not listed in the owner's manual.

A post accident flow test of the fuel servo unit revealed in the servo exceeding the upper flow limit by 1 2/3 gallons per hour (see attached report) or 7.47 gallons for the 4.5 hour flight. Using the Lycoming Operator's Manual, the fuel flow at the pilot's described flight conditions of 4,000 feet mean sea level, 23 inches manifold pressure, and 2500 rpm, was 11.3 gallons per hour at best economy mixture setting, and 13.0 gallons per hour at best power mixture setting. Based on these figures the fuel expected to be used during the 4.5 hour flight would be as follows:

best economy: 4.5 hours X 11.3 gallons/hour = 50.85 + 7.47 gallons = 58.32 gallons best power: 4.5 hours X 13 gallons /hour = 58.5 + 7.47 gallons = 65.97. Normally expected fuel for start, taxi, and run up is two to four gallons.