Tuesday, May 20, 2008
Tiger Or Demon In Your Tank?
Misfueling 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.
Recently, the misfueling issue attracted attention because of an accident that occurred on March 2, 2008. Shortly after taking off, a single-engine Cirrus SR22-G3 Turbo crashed into the upper floors of a condominium building in Rio de Janeiro, Brazil. All four people on board were killed. The SR22 was marked with the word “Turbo,” referring to its turbocharged engine. Preliminary information indicated that the lineman who fueled the airplane has mistakenly interpreted the word “Turbo” to mean that the airplane was powered by a turbine engine. Therefore, he fueled the airplane with Jet A.
In a 1998 advisory circular, the FAA suggested that turbocharged aircraft owners remove any decals from the fuselage stating “Turbo” or “Turbocharged.” In the past, these markings have given the wrong impression to inexperienced line personnel.
Misfueling first attracted real attention back in 1970 when a twin-engine Martin 404 with two pilots, two cabin attendants and 29 passengers crashed shortly after departing from DeKalb-Peachtree Airport in Atlanta, Ga. The airplane was carrying approximately 800 gallons of fuel. The weather at the time was 400 feet overcast; visibility was one mile in light rain and fog. During climb, there was a loss of power from the #2 engine; the pilots suspected carburetor icing. While they were trying to restore the #2 engine, the #1 engine lost power. The flight crew declared an emergency and reported that they were going down. The departure controller gave them a vector toward Atlanta International Airport, seven miles away, for an emergency landing. As the airplane glided below the overcast layer, the pilot noticed an interstate highway and decided to land on the median strip. The airplane struck a car, killing all five people inside, and struck the side of a highway bridge were it came to a stop. There were no on-board fatalities. The NTSB found that, rather than 100-/130-octane avgas, Jet A had been pumped into the airplane. The investigation concluded that the two linemen who had refueled the airplane hadn’t received formal training. Both said they knew they were putting Jet A into the tanks and had previously refueled Martin 404 airplanes with that fuel. (As it turned out, those particular 404s had been fitted with turboprop engines, not piston gasoline engines as in the accident airplane.) The accident airplane didn’t have decals at the fueling ports to indicate the type of fuel it used. As a result of this accident, the NTSB recommended that the FAA require placement of a colored circle—corresponding to fuel color—around each fueling port. The NTSB also recommended that each fueling nozzle be marked with the appropriate fuel color.
In 1975, the FAA proposed mandating just such a color-coding system. It included a requirement that no person may operate an aircraft unless it has been determined that it received the proper fuel type. The FAA withdrew its notice of proposed rulemaking after receiving more than 400 negative comments from several airlines and such groups as AOPA, EAA and NBAA. The system did, however, take hold on a voluntary basis.
When a gasoline engine is exposed to Jet A at takeoff power, detonation, high cylinder-head temperatures, loss of power and complete engine failure occur. The effects of Jet A in the tanks won’t be apparent until residual gas in the fuel system has been drawn through. Unless there’s been a long run-up and hold, this tends to coincide with takeoff. Interestingly, in an emergency, most turbine engines can run on gasoline for a limited time. If a jet aircraft is operated on gasoline, any run time should be logged in the maintenance record, and the fuel system should subsequently be purged.
In 1982, after investigating 13 more accidents where jet fuel was inadvertently used (resulting in 11 fatalities and nine serious injuries), the NTSB proposed that the industry develop a system to physically prevent jet-fuel nozzles from fitting into avgas tanks. Ideally, the physical differences would be maintained throughout the distribution chain.
In 1987, after investigating 19 accidents involving Piper PA31, Gulfstream Commander and Cessna 300/400 airplanes, the NTSB asked the FAA to issue an airworthiness directive requiring that those airplanes be fitted with port restrictors so that jet-fuel nozzles couldn’t be put into gasoline filler ports. The NTSB noted that PA31 Navajo (piston) and PA31 Cheyenne (turboprop) models look very similar.
The NTSB reported on a Canadian DC-3 cargo plane that crashed during its third attempt to take off from St. Louis, Mo., en route to Toronto, Canada, on January 9, 1984. After the second aborted takeoff, the pilots radioed the FBO to ask what type of fuel was put in the tanks. They were told that it was 100LL. On the third takeoff try, both engines lost power just as the landing gear was retracted. After the left wing hit a utility pole, the aircraft went through a fence and hit a highway embankment. The captain was killed; the first officer received serious injuries. The airplane had been serviced with Jet A.
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