At Last, A Low-Cost Aviation Gasoline That Gets The Lead Out

The Federal Aviation Administration (FAA) recently certified the fuel, which is about 85 percent ethanol and contains a high-octane petroleum product and agriculturally derived "biodiesel" for lubrication. Because of its high percentage of agricultural components, the fuel is known as AGE85.

AGE85 was developed during a three-year research project funded by the South Dakota Corn Utilization Council (SDCUC) and the U.S. Department of Agriculture (USDA). The National Alternative Fuels Laboratory (NAFL) formulated the fuel at the University of North Dakota Energy & Environmental Research Center (EERC).

Aircraft testing and certification were performed by South Dakota State University in Brookings, Great Planes Fuel Development in Watertown, S.D., Lake Area Technical Institute in Watertown, and Texas Skyways of Boerne, Texas.

Currently, aviation gasoline (known as "avgas") for piston-engine aircraft contains four times more lead than was used in leaded automotive gasoline before it was banned from use in new cars in 1973. However, because the lead additive has been the most economical method for achieving 100-octane fuel, leaded avgas has remained the standard for high-performance piston-engine planes.

To avoid damaging the general aviation industry, the U.S. Environmental Protection Agency (EPA) agreed to permit the use of leaded avgas until an economic alternative was developed. That time has come, according to Ted Aulich, the EERC research manager in charge of the NAFL.

"We believe that AGE85 is the economic alternative," Aulich says. "Based on a current price of pure ethanol at 95 cents a gallon, AGE85 is expected to sell at the pump for about $1.10 per gallon, compared to the current avgas price of $2 per gallon."

Jim Behnken of Great Planes says, "AGE85 is a high-performance, high-octane fuel -- just what newer, high-performance, high-compression aircraft engines need."

In flight tests and engine teardown inspections conducted over the last year in San Antonio, Texas, Behnken says AGE85 was demonstrated to meet or exceed FAA performance, materials compatibility and engine component wear specifications. It was approved for use in several different models of Cessna aircraft equipped with Continental engines.

Behnken says that the engine wear observed following the mandated 500-hour endurance test was so minimal that the FAA has waived the test as a requirement in ongoing and planned AGE85 certifications for additional aircraft models.

"Achieving initial certification is probably the most difficult step in getting a new aircraft fuel approved," says Dennis Helder of SDSU. "As the FAA certifies AGE85 for use with more engine and airframe combinations, it will become easier for additional aircraft to be certified.

"Our objective is to have at least 50 percent of the current aircraft fleet certified within the next year and a half," he says. "Eventually, all piston-engine aircraft should be certified to use AGE85."

According to Aulich, the ethanol used in the new fuel is produced mainly from corn and other grains. The biodiesel component can be made from many different crops, including soy beans, sunflowers, canola and cotton seed. In addition, waste products such as fryer oils and cooking grease, as well as beef tallow and pork lard, can be used.

Aulich says the current avgas market in the United States alone is about 600-700 million gallons per year and current ethanol production is about 1.2 billion gallons per year. With other nations showing a strong interest in AGE85, the demand for ethanol could be significantly expanded, he says.