When the famous Howard DGA-6 replica “Mister Mulligan” performed in the air show at the 2024 SUN ’n FUN Aerospace Expo, it made another kind of history.
It became the first airplane to fly on G100UL high octane unleaded avgas in an air show.
Developed by General Aviation Modifications Inc. (GAMI), G100UL was approved in September 2022 by the FAA for use in all spark ignition piston engines in the FAA’s type certificate database through the Supplemental Type Certificate process.
This means if you want to use the fuel in your airplane, you’ll have to buy an STC.
More than 650 STCs have been sold so far, according to company officials.
And we should see more and more airplanes using the unleaded fuel as GAMI officials report that Vitol Aviation has produced 1.2 million gallons of G100UL, making it “commercially available.”
The fact that the fuel has been produced in volume, tested, and made “commercially available” is significant because of a consent decree in California, which requires avgas fuel distributors and FBOs to transition to an unleaded fuel as soon as one is deemed “commercially available,” GAMI officials said.
According to GAMI’s George Braly, that consent decree was signed by all 100LL avgas fuel distributors and most of the FBOs in the state.
But while GAMI officials say the fuel is commercially available, others in the general aviation industry dispute that, including the National Air Transportation Association (NATA), which says until the fuel goes through the ASTM approval process, FBOs and aircraft owners will be hesitant to use it.
But GAMI officials say that years of testing and approval through several layers of the FAA hierarchy proves the fuel is safe to use.
The company’s quest to produce an unleaded fuel for general aviation to replace 100LL started 15 years ago, in October 2009, and the company has overcome numerous roadblocks in the ensuing years, including numerous reviews by different offices and departments by the FAA.
When the FAA’s Wichita office completed its review in 2022, officials there told GAMI that the “G100UL avgas STC project is the single most thoroughly vetted and documented STC project in memory in that office.”
Having a sophisticated engine test stand in house proved to be critical to GAMI’s success, according to Braly.
“In addition to testing our own unleaded fuel, we learned a lot by testing fuel sent to us by other companies, which all failed,” he said.
The fuel will probably be more expensive than 100LL, but that higher price will be compensated for by a few factors, including a “higher BTU energy content,” Braly said. BTU (British thermal unit) is a measure of the heat content of fuels.
Other advantages of using the unleaded fuel include not having to clean or change spark plugs as often, according to Braly.
Braly also cited oil analysis test results from Blackstone Laboratories that showed a 40% to 50% reduction in engine wear metals, which should result in longer TBOs.
Braly praised Aircraft Owners and Pilots Association President Mark Baker, who arranged for the use of a Baron twin with freshly overhauled engines as a testbed for G100UL. The left engine is operated on GAMI’s unleaded fuel, while 100LL is used in the right.
“The Baron’s engines now have around 170 hours each and the engine running G100UL consistently burns about ½ gallon less in cruise,” Braly said.
Another fan of the fuel is Doug Rozendaal, who flies “Mister Mulligan.”
The Howard replica is powered by a Pratt and Whitney R-1340 engine, but Rozendaal has also flown with G100UL in his 10-1 compression Lycoming-powered TRF-1 Rocket.
“In both aircraft there were no operational differences between G100UL and 100LL fuel,” he said. “Fuel flows were slightly lower and EGTs slightly higher, but imperceptible without modern engine monitoring. Based on my experience I believe G100UL is a suitable drop-in replacement for 100LL fuel.”
In response to a question at a forum held during SUN ’n FUN, Braly assured the audience that G100UL and 100LL can be mixed with no problem. He also added that GAMI’s fuel is easier to handle, since there is no lead content.
“This is a historic day,” Braly concluded. “The move to unleaded fuel is absolutely critical to the future of general aviation.”
Greetings…
Juan Browne (‘Blancolirio’ channel) has taken exception to the new ‘GAMI G100UL’ fuel.
His just released short explains how this fuel can soften certain fuel tank access seals, causing fuel leaks that strip and does major damage to the finish on aircraft.
https://youtube.com/shorts/4vezjpMlBHI?feature=shared
An FYI…
Gary
Tand cause leaks
STC police is pretty funny – like all the other STCs, it’s up to us to stay in compliance. I am ready to buy the STC, but I have to be able to buy the gas at either my home airport, or at least nearby. A map of availability, updated regularly, would be great.
Could this new unleaded fuel be an accident waiting to happen? Don’t forget, the FAA also “APPROVED” airmen getting the clot-kill-shot-jabs… and now look at all of the deaths and disabilities that were caused by the Pfizer and Moderna (DARPA) COVID-19 vax deal! Plus, MILLIONS of deaths worldwide, including healthy athletes in their teens, twenties and thirties. It’s all coming to light now – after the fact!
U.S. Army Lt. Col Theresa Long, a Senior Flight Surgeon responsible for the Army’s 4,000 flight-ready airmen at Ft. Rucker, Alabama was tossed out after she blew the whistle in 2021. But now the lawsuits have begun with discovery and evidence and there’s a different tune being played. Attorney Todd Callender is leading the way, along with German Attorney Reiner Fuellmich, and many others.
Testifying under the Military Whistleblower Protection Act, Lt. Col.Theresa
Long told U.S. Senator Ron Johnson that she had grounded
vaccinated pilots to monitor symptoms of myocarditis — including chronic
fatigue — that could cause them to die of heart failure in mid-air.
Dr. Drew interviewed Lt. Col. Theresa Long on December 21, 2022, and here’s the link if you care to investigate the biggest crime of the century: https://www.youtube.com/watch?v=YtnFPnNG1sc
As you watch, ask yourself if the new unleaded juice is “SAFE” for YOUR airplane… as was the COVID-19 vaccine, which was continually advertised as “SAFE AND EFFECTIVE” for YOUR body!
Do YOU want to be a “test-tube-flyboy” with the new juice in your turbocharged, high performance airplane? NOT ME!
This is not the forum for your crazy, unfounded, conspiracy theory rant.
Please take your conspiracy ramblings elsewhere. Like, preferably to a therapist or psychiatrist.
Cordially
I’m one of those 650 STC holders. In GA we need to move forward to remain relevant. I’m eager to try the GAMI fuel in my Skylane.
I’ve been told that our Nor Cal airports may get an unleaded 100 in a year or two, and then the folks at Epic fuels reply to my inquiry….and they have no idea when they will have any UL100 available here…they said it’s working through their ‘risk management’ folks…ie; legal folks.
So, I’ll be waiting….
BTW, I’ve had an autogas STC for 40 years and have never been able to use it…no autogas without ethanol in CA..!!
i have a new IO-550 in my airplane installed less than 2 years, CMTechnical “The use of fuels that are not approved for your engine, will void your warranty” G100UL is not approved!
G1000UL is approved for all engines and aircraft that require normal 100LL
Like I mentioned in a previous comment, an ASTM Specification is NOT a certification. It is at best “one means of showing compliance, but not the only means”. I have nothing against an ASTM compliance demonstration, but only the FAA can decide about certification, and one of the other acceptable means can be an STC.
My feeling is that NATA only tries to protect their own interests ($$$). There is NO legal instrument to demand application of an ASTM Specification. A manufacturer can use whatever compliance demonstration he/she elects to employ, but has to prove to the FAA that it is a viable compliance demonstration. And only the FAA can decide.
As said, an STC is completely viable.
(I’m an ex-ASTM Subcommittee Chairman of an F44 aviation subcommittee.)
The Howard DGA-6 aircraft was powered by a Pratt & Whitney Wasp R-1340, which runs just fine on inexpensive, lead-free, ethanol-free, mogas. An STC has been available for it from Petersen Aviation for decades.
NOT until FULL ASTM certification may one say this is an acceptable fuel.
I asked the FBO at my ‘home’ airport when they expected to start selling G100UL.
They’re reply was maybe in a year or 2′. It depends on the availability to the distributor who supplies the avgas.
They also said that all the aircraft based at the airport would have to have the STC to use the fuel.
I didn’t ask if there will be some form of ‘STC Police’ ??
Maybe the pump will be programmed to require the STC number for the aircraft, in addition to the registration number.?
and that STC requirement is also going to apply to NON type certificated experimental aircraft/engines?????? How does the STC Police intend to enforce that?
WTH would that be necessary to police whether an aircraft has an STC? That is not done for auto gas STCs and furthermore, the fuel seller is not responsible for the end-use’s regulatory compliance no more than holding an A&P responsible for an operator not getting his annual done but continuing to fly illegally.