FAA states that approximately 50,000 airplanes are currently operating on unleaded mogas in the U.S.
These days, Petersen says, most automobile gasoline contains Ethanol, and Ethanol has been proven to be entirely incompatible with aircraft engines.
“There are many parts of an airplane that are incompatible with Ethanol,” says Desrosier.
According to AOPA, “the general aviation industry has significant concerns about Ethanol’s use in aviation.”
Petersen says that unless something is done to guarantee the distribution of conventional gasoline, there will be no suitable unleaded gasoline to place at airports or for individual owners to obtain on their own.
“It cannot be emphasized enough that the recent expansion of Ethanol in the gasoline supply is cutting off the only unleaded alternative to 100LL currently available to pilots in both the U.S. and Europe,” says Petersen.
The Coordinating Research Council (CRC) is a non-profit organization that directs engineering and environmental studies on the interaction between transportation equipment and petroleum products.
The CRC, led by the petroleum companies, has a committee soley dedicated to conducting research and development for a potential replacement candidate for 100LL avgas. The committee is called the Unleaded Avgas Development Group, and they have been working on the issue for more than a decade.
Based on a report published by the CRC earlier this year, which is a culmination of all the research on an avgas replacement to date, Desrosier now describes the general aviation industry as entering a transitional phase as far as this issue is concerned.
“We are in the process of evaluating all that data and making a determination as to what is the best possible unleaded avgas fuel that would be available today,” says Desrosier.
One answer Desrosier says that they did get from the report so far is that there is not going to be a seamless “magic bullet” fuel which can be utilized by both high- and low-compression aircraft engines.
Other alternatives to avgas include the certification of diesal piston engines which can operate on jet fuel. According to FAA, two engines have been certified to date and they estimate that about 200 of these diesal engines are currently operating in the U.S. in the Diamond DA-42 Twin Star, the Cessna 172, and the Piper PA-28 airplanes.
Teledyne Continental Motors also recently stated that it is developing a 300-horsepower diesal engine to replace some of its gasoline-based IO550 piston engines.