Plane & Pilot
Tuesday, May 20, 2008

Tiger Or Demon In Your Tank?


Fueling mishaps


NTSB DebrieferMisfueling occurs when the wrong type of fuel is pumped into an aircraft’s tanks. It could be that jet fuel gets pumped instead of gasoline, gasoline instead of jet fuel, automotive gas instead of aviation gas, automotive gas containing ethanol instead of auto gas with no additives, or something else yet to be devised by a creative fueling person.
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Also in 1984, a Cessna 402C operated by Provincetown-Boston Airline was taking off from Naples, Fla., on a Part 135 commuter flight. Night visual conditions prevailed. Just after takeoff, both engines quit, so the pilot executed a forced landing to a field. The aircraft was destroyed by the impact and a postcrash fire. One of the five passengers was killed. The NTSB reported that the aircraft had been refueled with Jet A instead of avgas. The Jet A fuel truck was parked where the 100LL fuel truck was usually parked. A lineman had accidentally used the Jet A truck, which was identical to the avgas truck, but for the decal used to identify carried fuel type. The investigation found that the lineman’s training consisted of just 30 minutes of reading the company’s maintenance manual on how to refuel different company aircraft.

By 1985, U.S. manufacturers voluntarily adopted standards for filler-port sizes on piston and turbine airplanes. Under the standards, the port on an aircraft’s gas tank had a maximum opening diameter of 2.36 inches. The spout on a gasoline nozzle had a maximum outside diameter of 1.93 inches. A port for a turbine fuel tank had a minimum opening diameter of 2.95 inches. Operators of gas-powered piston airplanes with tank openings bigger than the new industry standards were urged to install restrictors, which reduce the diameter of the tank opening, making it impossible to insert a jet-fuel nozzle into an avgas filler port. This installation could be done by any pilot/owner as part of preventative maintenance.

A newer fueling port for aircraft requiring Jet A is almost rectangular in shape, but with slightly rounded sides, measuring about 2.90 inches long by 1.40 inches wide. A newer Jet A nozzle, measuring 2.66 inches long by 1.13 inches wide, is designed to fit either old or new filler ports. The redesign was made bearing in mind that diesel-equipped airplanes may one day become a significant part of the fleet. Because a single-engine Cessna equipped with a diesel engine requiring Jet A could look virtually identical to a gas-driven model, the change in shape from classic, round tank ports seemed prudent.

No matter what steps manufacturers, fuel distributors or government agencies may take, the last line of defense against misfueling remains with the pilot. If using a self-serve pump offering a choice of fuels, make sure that you have correctly followed the selection procedure. Look for appropriate color coding and placards on the dispensing equipment and the aircraft. When placing a fuel order with an FBO, make certain there’s no question about the fuel type you’re ordering. Make every effort to be at the aircraft when the fuel is pumped. Check fuel samples. Jet fuel will leave a greasy spot on a clean piece of paper.

Being on hand for refueling might have made a difference for the pilot of a Beech B60. On August 1, 2007, the pilot called an FBO at Bismark, S.D., to pull out the airplane and add 30 gallons to each side. When the pilot arrived at the airport, the airplane had been refueled. During his preflight inspection, the pilot looked in the fuel tanks, and the liquid appeared to be blue, consistent with 100LL avgas. He subsequently started up, taxied and did pretakeoff checks; everything seemed normal. During the initial takeoff roll, the left engine “stumbled,” so he aborted and returned to the maintenance area where a mechanic came on board and performed a full power run-up. Everything seemed normal, so the mechanic left and the pilot taxied out again. After receiving a clearance for takeoff, he taxied onto the runway, held the brakes and set power to 35 inches of manifold pressure. Everything seemed good, so he applied full power and released the brakes. After liftoff, the pilot noticed a fluctuation in the manifold pressure on the right engine. He began a slight left turn. Then, the manifold pressure and fuel flow indications for both engines began to fluctuate. The pilot was unable to do anything about the power fluctuations and decided he’d better get down. The pilot had to maneuver to avoid trees, cars, houses and people before making an off-airport landing. The pilot escaped injury. A fuel receipt at the FBO revealed that the airplane had been refueled with jet fuel instead of gasoline.

Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other NTSB news. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.



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