The future of fuel

“We have to stop loving the problem and just fix it.” Those words, spoken by Lycoming’s Michael Kraft at the 2010 AirVenture, may sum up best the quest to find an unleaded replacement for 100LL.

Ostensibly, the industry has been working since the early 1990s towards finding a solution, but efforts didn’t really get serious until a few years ago. Many place the turning point at the AOPA Summit in Tampa, Florida, in 2009 when Glenn Passavant of the EPA made it very clear that it was time for the industry to get to work.

That was followed by a true wake-up call in April 2010 with the release of an advanced notice of proposed rule making from the Environmental Protection Agency, giving the GA community an opportunity to comment on data collection regarding lead and possible new environmental standards.

The folks at General Aviation Modifications Inc. (GAMI) in Ada, Okla., as well as the forces behind Swift Fuels, didn’t need that additional wakeup call — they were already hard at work in the search for an unleaded alternative.

At this year’s AirVenture, George Braly, who started GAMI in 1993 with fellow aerospace engineer Tim Roehl, described how the two spent the flight home from that eventful AOPA Summit sketching out ideas for an unleaded fuel.

They went to work in the company’s engine test facility and within a year began testing the new G100UL in the company’s Cirrus SR22.

By the spring of 2010 — right about when the EPA’s advanced notice came out — GAMI had a fuel that worked, Braly said.

Dubbed G100UL, the fuel fits the design requirements for an unleaded aviation fuel, he said. While GAMI officials won’t divulge what’s in the fuel — calling it a secret formula like the formula for Coca-Cola — Braly noted “there is nothing in it that hasn’t been running in airplanes in the past.”

In fact, G100UL can be mixed in any percentage with 100LL, so if a pilot wants to top off a fuel tank that already has 100LL with G100UL, there will be no problem.

“The fuel in the plane will still retain its spec and integrity and there will be no degradation in performance,” Roehl said.

The fuel has been flown by officials at Cirrus Aircraft, Lycoming, Continental Motors and the FAA. Embry-Riddle Aeronautical University has used the fuel in its Cirrus and Cessna 172s. In September 2012, G100UL was successfully tested for use in high-compression turbocharged aircraft, with four FAA officials there to witness the test, according to Braly.

All of the data shows that the fuel performs just as well as 100LL, GAMI officials noted.

The FAA has since approved G100UL for all certification testing activities, Braly added.

The company and the FAA recently reached an agreement on the list of airplanes that have to be tested to receive AML-STC (Approved Model List Supplemental Type Certificated) approvals.

Braly estimates the company will have the testing completed in about a year. “When we are through, we should have an STC list for all the airplanes in the FAA database,” he said.

The folks at Swift Fuels in the Purdue Research Park next to Purdue University in Indiana took a different tack, creating a new fuel — 100SF — through a mixture of two hydrocarbons. In English: 100SF is a biofuel, made of renewable sources, such as sugars and starches.

After seven years of R&D, the company is now transitioning to production. In fact, the company announced at this year’s AirVenture that officials had sent in the Swift Fuel research report to ASTM for FAA and OEM review and approval.

“The vote outcome is expected in several more weeks,” said Chris D’Acosta, CEO, on Sept. 3.

100SF has been tested in the Embry-Riddle fleet, as well as in all kinds of aircraft engines, from Pratt & Whitney to Lycoming to Continental to Hirth, Swift officials reported at Oshkosh. In fact, the engine test section makes up about 200 pages of the 400-page report submitted to ASTM.

That report also includes a materials compliance study from the University of Dayton Research Institute, which shows that 100SF is fully compliant with the engine, fuel systems and composites used in modern aircraft. Another test, conducted by researchers at Clemson University and Lewis University, show that 100SF is far and away less environmentally toxic than 100LL.

After all, Swift officials said at Oshkosh, “what good would it be if we put something in there that was as harmful as lead?”

While the industry continues to argue over the solution, there is one thing that everyone agrees on: Getting the lead out of avgas will benefit aircraft owners.

“All the positives we saw in cars we’ll see in aviation,” says Lycoming’s Kraft.

Once we get the lead out, there will be decreased maintenance costs because lead by-products affect the engine, as well as contaminate the oil. We’ll see increased equipment life and perhaps longer TBO times, industry insiders promise.

“Remember when we transitioned from leaded to unleaded autogas?” Braly asked the Oshkosh crowd. “We went from changing our spark plugs every 10,000 miles to every 80,000 miles. The lead in fuel is not good for anything except to protect the engine from detonation.”

In fact, Lycoming’s Kraft said the company would “love” to get rid of TEL — Tetraethyllead, the highly toxic additive in avgas — noting that in the company’s iE2 FADEC engine, the lead “messes up the sensors.”

Kraft, who has been at the center of the search for a 100LL replacement as a key member of the Aviation RuleMaking Committee, is pleased with the progress the industry has made over the past few years.

“We’ve learned a hell of a lot and with that knowledge, we’ve changed the outcome,” he said.

The debate has finally switched from fighting the EPA about keeping lead to finding new fuels for GA, he noted.

“There is a technical solution,” which must be music to the engineer’s ears.

Lycoming has made it very clear that it is more than willing to revise its Service Instruction 1070, which lists the approved fuel for its engines.

“Every time we revise SI1070 it is a signal to the fuel manufacturers that if you product a new fuel, we will approve it,” Kraft said. “If you throw us a fuel, we can tell you within two weeks if it will work.”


While all this is getting sorted out, pilots and aircraft owners need not worry about being grounded.

“There will be no precipitious end to 100LL,” said Doug Macnair, vice president of government relations for the Experimental Aircraft Association (EAA). “There is a methodical process in place that brings prudence to the industry.”

The process will begin with evaluating all candidate fuels on a level playing field. Initial candidate fuels must be submitted to the FAA, which will then choose the fuels that will actually be tested at the FAA’s William J. Hughes Technical Center in Atlantic City, N.J.

Testing of the fuels to identify the most viable replacements for 100LL won’t even begin until 2014, with certification not expected for several years beyond that. Some peg 2018 as the date to expect fleet-wide approval of the new fuel.

“We’re still talking years, not months,” Macnair said. “This is not going to happen overnight, nor should it.”

The lengthy process of standardized testing is critical, he added.

“This takes all the opinion and conjecture out,” he said, noting the fuels will be judged on “purely technical and economic factors.”

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