To help move general aviation’s unleaded future forward, Aircraft Owners and Pilots Association (AOPA) President Mark Baker flew a Beechcraft Baron twin-engine aircraft over Ada, Oklahoma, on Oct. 31, 2023, to begin a program to “demonstrate the efficacy and safety of General Aviation Modifications Inc.’s G100UL fuel, which received FAA supplemental type certification approval in 2022.”
“We wanted to get some actual experience with a 100-octane unleaded fuel in the kinds of airplanes and engines that our members own and fly,” Baker said. “This fuel has been tested extensively in labs and received an FAA STC. Should the FAA approve additional fuels, we’ll test them, too, so we can see what they’re like to use out on the airways.”
Baker flew the Baron for one hour with G100UL feeding the left engine and 100LL in the right. He said the performance of the two engines was nearly identical and “the Baron flew beautifully.”
The flight included several full-power takeoffs and a prolonged high-power cruise at more than 75% power.
Through this and future flights, performance will be analyzed by closely comparing the two engines operating at the same time on the same airframe, according to AOPA officials.
The engines will undergo regular borescope inspections and compression tests to compare internal engine wear.
As other unleaded fuels become more widely available for standard-category GA aircraft, AOPA intends to try them, using the same airplane and techniques.
“George Braly and GAMI have done a great deal of pioneering work preparing for general aviation’s unleaded future,” Baker said. “We’re staging the AOPA Baron at GAMI’s headquarters in Ada first to try out its G100UL.”
GAMI is currently working toward commercializing its fuel in order to distribute it more widely.
The Baron is equipped with two freshly overhauled, normally aspirated (non-turbocharged) Continental IO-520 engines. It also has new Garmin avionics, including an engine monitor capable of recording a wide variety of engine data, AOPA officials noted.
Mike Busch, founder of Savvy Maintenance and an AOPA Pilot magazine columnist, will analyze engine data from the Baron using Savvy’s computerized diagnostic tools. Savvy has gathered detailed engine data from hundreds of thousands of hours of GA flights and developed predictive diagnostic tools designed to anticipate engine component failures before they happen, according to associatin officials.
“The move to unleaded fuel is absolutely critical to the future of general aviation,” Baker said. “This airplane is a valuable tool because it can help us make the transition safely and confidently.”
>> “He (Baker) said the performance of the two engines was nearly identical…”
“Nearly” is one of those buzz words I personally dont want to hear during this ban and replace process. It introduces a fingers crossed vibe into the air. <<
Rest easy, my friend! It's true, GAMI's G100UL is 5% heavier than 100LL; I can easily handle the impact of the additional 15 pounds in calculating W&B on my Cardinal. But, because of the heavier weight, G100UL contains slightly more energy per gallon. This accounts for the "nearly identical" performance. G100UL with more energy makes slightly more power. And so the engine running G100UL will achieve peak EGT on slightly less volumetric fuel flow.
This is a small enough effect that it can be neglected… just use the same numbers you've always flown your airplane by. But, in a twin, with G100UL on one engine and 100LL on the other, you'll see those small differences, and that's what Mark is referring to.
Paul
Citing Valve Damage, UND Drops Unleaded Fuel And Returns To 100LL (Updated)
https://www.avweb.com/aviation-news/citing-valve-damage-und-drops-unleaded-fuel-and-returns-to-100ll
The big mistake – understandable, but short-sighted – was in focusing on finding a new high-octane fuel instead of getting all the engines to run on 94-octane unleaded avgas.
I know, I know. Many engine types. Loss of performance. STC costs. I know. I get it. I do.
We’ve had 94-octane unleaded for decades. There is environmentalist opposition to it, but we have political “air cover” from the nation’s motorists, who use essentially the same fuel. Once we add strange-sounding octane-boosting additives to our fuel… that “air cover” is gone. That’s a big deal.
Meanwhile, the performance hit of modifying existing engines would be pretty modest, and we could have done it decades ago. By now, new engines would all have adjusted for it.
Anyway, as I see it, not only are we dragging our heels on the path to unleaded; we’re on a path to the wrong kind of unleaded, and the “toxic aviation fuel” meme will still be with us.
It would have been nice to see this aircraft use something like UL94 on one of the engines. I think that the availability of UL94 is a lot more possible as an unleaded alternative just because it is already available. They might need some water injection or other modifications for this engine aircraft combination but it would be nice to see what could be instead of what AOPA dreams it should be, now going on 30 years.
This is brought about by a small minority of militant environmental whack jobs in positions of power.
No one else cares.
AOPA is just trying to cope with it.
1. Ignore the people in power at your peril.
2. Don’t forget that social groups tend to be “bubbles”: most people literally know only a very few people whose opinions, on a range of topics, are very different to their own. You, and the people you know, don’t care about the lead in the fuel. But, if you ask the people who live around the airports near San Francisco (for example), those people think everyone cares (they’re wrong, but it doesn’t matter) – and they want it to stop (which is why it matters).
3. I have wanted the lead out of the fuel for the several decades I’ve been in aviation, because it ruins our engines and makes them unreliable. That doesn’t require being a “militant environmental whack job” – it only requires being a “pilot.”
Keep in mind that as far as I’ve ever seen, the fuel has only been tested in the engines. It has not been tested on any airframes. This testing is important to see the short and long term effects the fuel may have on fuel tanks and bladders, fuel lines, fuel pumps, etc. Engine testing alone is insufficient for saying it is ready to go in our airplanes.
In fairness, GAMI does claim it has done that. It has also tested the fuel in – as I understand it – one (one!) composite airframe, a Cirrus.
AOPA under Mr. Baker has lost its way. I will not contribute.
Seems like a waste of my dues to have AOPA “testing” a fuel that is already approved. I find myself less and less well represented by AOPA when it comes to unleaded fuel. The organization seems to keep wanting to spend other peoples money (like EAGLE and this test) without actually moving the ball forward.
In AOPA’s press release about this project, it was noted that the use of the airplane and the fuel are being provided by a donor who has a particular interest in seeing how the unleaded fuel performs.
You are whining about the cost of a couple tanks of gas?
Really?
They are trying to promote an answer to a problem made up by the politicians.
I couldnt help but take note of the following sentence in the article.
“He (Baker) said the performance of the two engines was nearly identical……”
“Nearly” is one of those buzz words I personally dont want to hear during this ban and replace process. It introduces a fingers crossed vibe into the air.
I had an engine once that developed a fuel delivery system issue and after repairs it left the shop running at less than peak performance. I pointed this out to the mechanic who said “It might be a tad off. It will be OK”. After a year of running “a tad off”, words akin to “nearly”, it started to throw an internal combustion fit. We fixed it before it nearly destroyed itself, took the incident as an opportunity to learn and banned “a tad off” from our shop.
You’ll convince me we have a replacement solution when long term aviation community stats provide solid evidence we have an equal performing replacement fuel available………and none of this nearly stuff.
Final note………I’d like to point out another comment Baker made in this article. He stated “the Baron flew beautufully”. That sir is a fact. If you’re airborne, in a pinch and the placard says Beechcraft, it will fly beautifully no matter what you throw at it. Even if one of your two engines is a tad off.
Big deal. The president of the EAA, Paul Poberezny, flew with the “old” unleaded aviation fuel a half century ago, when the EAA was issued the first STC for Mogas.
Well, that’s nice of them..!! But Gami has been testing this fuel over the last 10 years.
Why do more redundant testing ? How long will they run these engines…1,000 hours ?
how many months/ years will that take ?
Then what, tear them both down to see any differences ? That’s a test on 1 engine !
Just get it produced in the needed volume and to our airports !