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Running on airRunning on air

CHI08FA132 CHI08FA132 

By David Kenny

Accidents caused by fuel exhaustion often inspire the sage observation that “They’re not called ‘airplanes’ because they run on air.” Helicopters aren’t called “airplanes” at all, but they don’t fare any better with air in the tanks.

On May 16, 2008, a Fairchild-Hiller FH-1100 hit trees near the top of a ridge about five miles east of Kalamazoo, Mich. The crash destroyed the helicopter and killed the 68-year-old solo pilot, who had bought the aircraft the day before. The pilot was returning to his private airstrip from a small airport west of town after an hour of dual instruction; his strip was visible from the accident site, barely half a mile to the south.

The pilot picked up the helicopter in Wisconsin the day before the accident. His 2,100 hours of flight experience included almost 900 in helicopters, but there is no record that he had ever flown an FH-1100. A CFI joined him for the ferry flight. Their last known fuel stop was at Michigan City, Ind., 82 miles from the pilot’s home.

The FH-1100 has a usable fuel capacity of 66.9 gallons and burns 22 an hour, good for three hours aloft with no reserves. Cruise speed is typically 85 to 90 mph, so the final cross-country leg from Michigan City to the private strip should have taken just about an hour. The next morning, the pilot flew 22 miles to pick up the CFI at the airport west of town, and they spent about an hour doing air work and practicing autorotations. The CFI later told investigators that the helicopter was “operating normally” and that the pilot was “not having any problems” flying it. He also described the fuel gauge as “unusual,” though the NTSB report doesn’t go into detail.

A rough calculation suggests that about 45 minutes of fuel remained when the pilot dropped off the CFI and started home—not a lot, but enough for a 15-minute flight with VFR reserves. According to the instructor, the pilot left at about 11 a.m. The accident occurred at 11:53 a.m.

There is no record of where he went in between, though the pilot’s wife said that he overflew their property once and was coming back around to land when she heard the impact. First responders didn’t notice any smell of fuel around the wreckage, and accident investigators found only two quarts in the tank.

Perhaps the pilot simply decided to enjoy some pleasure flying. He probably stayed in the air; the time of the accident corresponds closely to the aircraft’s remaining endurance at takeoff. It’s not clear whether he was misled by the “unusual” fuel gauge, neglected to brief the operating specifications, or just lost track of time. The extra pass before landing suggests that he wasn’t aware of his precarious fuel status even then.

What is clear is that flying a new aircraft for the first time requires additional care, especially with regard to fuel planning. Even if it’s a familiar model, that particular engine and airframe may not perform as specified, and a pilot with little time in type should be especially suspicious of the performance figures in the pilot’s operating handbook. A good rule of thumb for the first flight is to assume a fuel burn significantly higher than advertised, and then plan for more than one hour’s reserve. After timing the flight and topping the tanks, you’ll begin to gain a solid basis for your flight planning. Doing this repeatedly, with different loads at different altitudes in varying weather conditions, will help develop a sense of how much fuel consumption can vary—and how much flight time you can really count on.