MEXICO, MO, USA
N4255Q
HARD MAXAIR DRIFTER
THE PILOT REPORTED THAT HE BASED HIS FUEL CALCULATIONS ON THE TYPICAL FUEL BURN OF 4.5 GALLONS PER HOUR. ON THE FIRST LEG OF THE FLIGHT, HIS CALCULATIONS WERE ACCURATE. HE REPORTED THAT ON THE SECOND LEG OF FLIGHT, THE ENGINE QUIT RUNNING AS A RESULT OF FUEL EXHAUSTION, LESS THAN A MILE FROM HIS DESTINATION. SUBSEQUENTLY, THE AIRPLANE WAS DAMAGED DURING AN OFF-AIRPORT LANDING. THE ENGINE WAS TESTED FOR FUEL CONSUMPTION, AND IN ONE TEST, IT HAD AN ABNORMALLY HIGH FUEL RATE OF 6.51 GALLONS PER HOUR. THE TEST ALSO REVEALED FUEL LEAKING AT THE PTO CARBURETOR FLOAT BOWL VENT. AFTER CLEANING AND INSPECTING THE NEEDLE AND SEAT, NO FURTHER ABNORMAL FUEL CONSUMPTION WAS NOTED. THE PILOT REPORTED THAT HE HAD NOT TESTED OR CALIBRATED HIS FUEL INDICATOR AND DID NOT KNOW HOW MUCH FUEL REMAINED IN THE TANK BY VISUALLY CHECKING THE FUEL INDICATOR. HE HAD DECIDED AGAINST REFUELING EN ROUTE BASED ON HIS AVERAGE FUEL BURN CALCULATIONS.
On September 23, 1995 at 1845 central daylight time, an experimental Maxair Drifter, N4255Q, sustained substantial damage during a forced landing due to loss of engine power near Mexico, Missouri. The private pilot reported no injuries to himself or to the passenger. The 14 CFR Part 91 flight departed Wheatland Field, Aurora, Illinois, en route to Mexico, Missouri. Visual meteorological conditions prevailed and no flight plan was filed. The pilot reported that he had refueled at Ingersoll Airport, Canton, Illinois, and completely filled the twelve gallon tank. He reported that the fuel burn on the previous flight leg had averaged 4.7 gallons per hour. Averaging a 64 knot miles per hour ground speed, he determined he should reach his destination of Mexico, Missouri, which was 119 nautical miles away, in about one hour and forty-five minutes. He calculated that he should have a forty-five minute fuel reserve when he reached his destination. He reported that he departed Ingersoll Airport at 1700 central daylight time, and that the engine quit running as a result of fuel exhaustion at 1845 central daylight time, within one half mile from runway 24 at Mexico Memorial Airport, Mexico, Missouri. The pilot reported that he had checked his fuel remaining when he was fifteen miles south of Hannibal, Missouri. He calculated that based on the fuel flow on the first leg of flight, he should have been able to fly to his destination without refueling. He reported that he chose not to divert for refueling but continue to fly to his destination. The pilot/owner, at his own expense, shipped the engine and propeller to Green Sky Adventures, Inc., a distributor of Rotax engines, in order to test the engine for abnormally high fuel flow. Green Sky Adventures conducted a series of tests to determine the average fuel flow. In one test, test #5, they noted an abnormally high fuel rate of 6.51 gallons per hour fuel burn. Their report concluded that, "Test #5 resulted in excessive fuel consumption, out of norm. Fuel was found leaking at the PTO carburetor float bowl vent. No foreign material or contamination could be detected at the float needle or seat, although after cleaning and inspecting the needle and seat, no further abnormal fuel consumption was detected." The 119 nautical mile flight should take one hour and fifty-two minutes if flown at 64 nautical miles per hour ground speed. If the engine had an abnormally high fuel burn of 6.51 gallons per hour, the total flight endurance with 12 gallons of fuel on board should be one hour and fifty-one minutes. When the fuel used during taxiing and engine checks is taken into account, the fuel endurance would be even less. During a telephone conversation, the pilot stated that the Maxair Drifter is a two seat, pusher type ultra-light airplane. The pilot stated that the fuel tank was located behind and above the aft seat. He reported that the airplane did not have a fuel gauge, but that the fuel indicator was an eighteen inch by 3/8 inch clear tubing located on the fuel tank. The pilot stated that he last checked the fuel indicator about 5 to 8 miles from his destination, and that there was about three inches of fuel showing in the clear tubing. He stated he thought there should be enough fuel to fly to his destination. He stated that he did not know how much fuel, or how much flying time, was available when the indicator had three inches of fuel remaining. He stated that he had never tested or calibrated the fuel indicator for the corresponding amount of fuel remaining in the tank.
fuel exhaustion as a result of excessive fuel flow, and failure of the pilot not properly monitoring fuel consumption. Rough/uneven terrain in the emergency landing area was a related factor.
Source: NTSB Aviation Accident Database
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