Embry-Riddle: GAMI G100UL Tests Looks Promising

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Embry-Riddle Aeronautical University’s testing of GAMI’s G100UL unleaded fuel looks promising, the school told AVweb last week, and it says it sees no reason why the fuel can’t be a drop-in replacement for 100LL. 

With two major flight training campuses, ERAU wants an unleaded replacement for avgas sooner rather than later and has been testing both Swift Fuel and General Aviation Modifications Inc.’s G100UL in a school Cessna 172. “Our students are green aware and they’ve made it clear we want to go in the direction of eliminating leaded fuel. If we can get an unleaded fuel, we would like to get out of 100LL, no question. We’re footing the bill for what we’re doing in the testing,” said ERAU’s Pat Anderson, who’s overseeing the G100UL test program at the school’s Daytona Beach campus.

ERAU’s test program is divided into three phases: a FAR Part 23 airframe certification test including climbs, shutdowns and restarts and a FAR 33 150-hour in-flight longer-term performance trial. Phase three will repeat the initial testing to identify any differences in findings. The test aircraft is a Cessna 172 with an engine at TBO, but with two new cylinders that will allow gauging wear that might not be evident on the run-out cylinders. Anderson expects the flight trials to be done by the end of the year with further testing, perhaps an operational pilot program, to follow.

Anderson says the testing ERAU has done so far reveals no performance shortcomings in G100UL that would rule it out as a replacement fuel. Other than smell, Anderson said, there’s not much noticeable difference between G100UL and avgas.

“I know some people are saying there’s no drop-in replacement for 100LL, but this looks a hell of a lot like a drop-in replacement to me,” Anderson told AVweb.

Two barriers that remain to deployment of a new fuel—G100UL or any other--are cost and certification. In 2011, the FAA set up an Unleaded Avgas Transition rulemaking committee to develop a testing and certification procedure for new fuels. The UAT-ARC evolved into an FAA office dedicated to certifying a 100LL replacement and in June, the FAA asked the industry to begin submitting proposed fuels for testing, a process that could take years to complete.

Anderson says ERAU would rather not wait, so it’s supporting GAMI’s effort to field a fuel through the STC process, with approved model lists for hundreds of aircraft and engines. As for cost, Anderson says the components in G100UL suggest it should be comparable to what ERAU is now paying for avgas or at least affordable for the university’s operating budget.

GAMI’s George Braly says the company has always maintained G100 would sell for a price within 10 percent of current avgas prices, although the difference could be as much as a dollar more. G100UL is composed primarily of aviation alkylate—the base refinery stream for 100LL—but without any lead, with octane enhanced by the addition of aromatic compounds such as xylene or mesitylene. G100UL’s octane is typically just above 100, making it suitable for any engine requiring 100-octane fuel.

Braly told AVweb this week that its testing toward completing the STC is proceeding, but at a slower pace. “We think we could finish it in 12 months, but we’re resource-limited,” he said. ERAU’s project will complete two of the six testing milestones required, including the Part 23 airframe test.

Braly hopes to avoid the cumbersome FAA fuels certification process entirely by obtaining an all-aircraft, all-engine STC for virtually every aircraft and engine combination flying.

“We could then get a million gallons a year to Embry Riddle so they can get rid of lead at their airport,” Braly said. “That starts the ball rolling and my expectation is that once there’s an approved unleaded replacement, it’s not going to take the state of California more than a couple of months to ban lead. And that starts the dominoes falling,” Braly added.