General Aviation Modifications, Inc. (GAMI) has received an FAA STC for its G100UL unleaded aviation fuel for use in some Lycoming O-320, O-360, and IO-360 piston engines.
The FAA’s Approved Model List (AML) STC means specific engines and aircraft are approved at first, with the AML expanding based on additional data and testing, according to GAMI officials.
“These AML-STCs are the ‘beginning of the end’ for the continued use of lead in aviation gasoline,” said Tim Roehl, GAMI president.
Eventually, as more aircraft are approved to use the fuel, GAMI officials predict their unleaded avgas could meet “North America’s demand for high octane aviation gasoline within the next four years.”
GAMI is collaborating with Avfuel to work through the logistics of distributing the first-ever high octane unleaded avgas.
“Once the FAA expands the AML and production of G100UL avgas expands to support the needs of the market, GAMI anticipates the existing blue 100LL avgas will disappear from the market, providing a long-awaited solution to the environmental and engine operational pitfalls of leaded fuel,” officials claimed.
Testing continues to expand the Approved Model List, company officials note.
“When these tests are completed, the pathway to a large expansion of the Approved Model List will be clear, and when the AML is fully expanded, G100UL avgas will provide a functional fleet-wide drop-in replacement for 100LL.”
GAMI officials note they have been working “diligently” for the past 11 years to develop a “functional drop-in unleaded avgas solution that maintains or improves engine performance and, simultaneously, significantly reduces routine maintenance costs imposed by the use of leaded avgas.”
They acknowledge that developing a commercially viable unleaded high-octane aviation gasoline proved to be a complex challenge due to a myriad of technical and economic issues. The No. 1 challenge: Developing a single high octane unleaded avgas that is compatible with all of the existing aviation gasolines when the different existing fuels are co-mingled in the fuel tanks of aircraft.
“G100UL avgas can be mixed with 100LL in any proportion, and is compatible with the existing fuel infrastructure without modification, enabling its immediate adoption into the marketplace and seamless transition from 100LL,” company officials say.
“In addition, G100UL avgas can be produced both by current fuel producers in the industry or within the specialty chemical processing industry, helping to maintain a competitive cost structure and widespread availability using the existing avgas distribution infrastructure.”
Aug. 17, 2021 update: Petersen Aviation was awarded STC SA01757WI on Aug. 26, 2014 “to allow the use of UL91 or UL91 (minimum) grade aviation fuel per ASTM D7547 (currently marketed by Swift Fuels)” and awarded STC SA01831WI on Jan. 24, 2017 “to allow the use of UL91(minimum) grade aviation fuel per ASTM D7547 (marketed by Petersen Aviation).” The original headline incorrectly credited GAMI was earning the first STC for unleaded avgas.
What about Swift Fuels UL94 that is FAA-Certified for approximately 60% of general aviation planes
How about a link to the STC list!???
LOP may NOT be the way to operate low compression non-intercooled turbo-charged aircraft. There appears to be a pattern of field observations where EGTs pushed into the 1500s can inflict damage to the exhaust port components. There is literature that supports mixture is the dominant determiner of valve temperature in air-cooled aircraft engines. Notably this damage can be done in the exhaust components without ever showing up as high CHTs because of LOP’s other virtues of controlling CHT. No one has offered direct measurement of temperatures in the exhaust components in this class of motor including GAMI. Beware of high EGTs in low compression non-intercooled turbo-charged motors, specifically the TSIOs, until this matter is more thoroughly investigated.
I’m confused by your thoughts about high EGTs. You seem to be indicating that LOP operations result in high EGT. However, when I run LOP, both my CHTs and EGTs are lower. So could you provide some references/information?
The P is actually peak temperature, which along with power is north of peak fuel efficiency, 14.7 to 1 by weight, which you have no way of determining.
Lean of peak mixture is less power and cooler. Rich of peak mixture is more power and hotter….to a point and then starts falling off. So with temp monitoring you are playing somewhere unknown rich of stoichiometric charge.
This is an important first step, but until the STC can be extended to the overwhelming majority of airframe/engine combinations, widespread distribution will not be cost-effective. It has to be a true drop-in replacement for the vast majority of piston airplanes. Otherwise, costly infrastructure would have to be duplicated, driving up the costs quite substantially.
Article says “…. end for blue ….”.
What color will it be and result color of mixing with blue?
This is NOT the first STC for unleaded fuel. Both EAA & Petersen developed STCs for unleaded auto fuel many years ago.
“Mogas” works great & has provided the benefits of unleaded fuel as well as significant cost savings for thousands of aircraft owners.
Yes… but you may be missing the elegance of this solution. GAMI’s solution is being applied to both low compression engines and high compression engines. That is, it includes engines that cannot utilize mo-gas. A drop-in replacement for 100LL with the same or better performance is a significant achievement.
Unleaded mogas and unleaded avgas are two different things. Mogas isn’t STC’d for my Mooney, among other higher performance aircraft, because of vapor lock.
But the headline says “unleaded fuel”, so is misleading.
GAMI, once again can be very proud. They also brought scientific evidence to prove ‘lean of peak’ is the proper way to fly our engines. After 11 years of careful, intense study of the intricacies of fuel, GAMI found the solution to the problem of many airplanes not being able to fly with gasoline not containing lead. This is an historic evolution in General Aviation flying, which will lead to longer engine life with far less pollution. Congratulations GAMI, and thank you.