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Unleaded Aviation Fuel

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Dave Baxter

Well-Known Member
Lifetime Supporter
Nov 14, 2007
Reaction score
Along with some of the recent issues in finding building material to build our airplanes, this is another thing that could impact our flying light of airplanes in the near future?

I am sure many on the forum are AOPA members, and have probably already read this, but for many myself included the silver bullet of unleaded fuel has been a long time in coming and an ongoing frustration. If one reads this, the problem I see is the regulating and demise of 100LL before any meaningful unleaded equivalent is available. For me with my O-360-A2A, and my O-290-D2 unleaded fuel, even current alcohol free automobile fuel would probably work, my concern with both of the engines I have is the PS-5C pressure carbs, even with the later red silicone diaphragms as I am not sure how well the current and the future unleaded fuel will work in them? The other problem is, if one like me wants to fly across country will suitable fuel in the unleaded variety be available and especially at the smaller airports? However My son Dan's IO-540-G1B5 290 HP requires 91/96 100/100LL Octane minimum, which in the unleaded variety may or may not work well?

By Paul Millner AOPA
The ability to create an unleaded avgas that meets the needs of the entire general aviation fleet has been vexing the industry for decades. There has been recent progress, but challenges remain.

In an effort to continue progress, the FAA hosted an industry round table discussion on unleaded avgas on November 15 in Washington, D.C. AOPA attended, as did a cross section of oil companies, independent unleaded avgas developers, Textron Aviation, a smattering of independent experts, and other trade associations representing airport operators, FBOs, and manufacturers.
The round table attendees are working to tackle one of the toughest issues facing general aviation: the removal of lead from avgas. Recent developments seem promising, but in many ways they—combined with heightened environmental concerns—have also led to confusion and angst for aircraft owners.

From the beginning of the effort to develop an unleaded avgas, AOPA has held the position that the only acceptable solution is one that meets the needs of the entire fleet of 200,000 aircraft.
With FAA approval of General Aviation Modifications Inc.’s (GAMI’s) 100-octane unleaded avgas for a small number of engines and airframes this past July, pressure on both the EPA and the FAA to address lead phaseout has increased. At the meeting, the FAA estimated the EPA/FAA process to ban leaded gasoline would take four to six years. However, at the National Association of Clean Air Agencies meeting in October, the EPA said it’s refocusing on an endangerment finding, a significant milepost in the process to ban lead. European regulators are also moving toward banning tetraethyl lead imports, now that the sole manufacturer, in England, is outside of the European Union. TEL is the octane-boosting component that contains lead. However, several airport operators are not waiting. Regulators and airport operators in a handful of mostly Western states have begun moving toward banning the sale of leaded avgas, even though a 100-octane unleaded fuel is not yet available.
While some pilots like to argue that the amount of lead emitted by general aviation is tiny, any amount of lead is a problem.
The EPA has been very effective over the past 40 years in moving industry to reduce lead from automotive fuel. Avgas emissions have gone down as well (with the transition from 100/130 to 100LL). However, avgas-related lead emissions remain an issue.

Moreover, there’s a security of supply issue. The last leaded mogas (motor gasoline, designed for automobiles) blender in the world earlier this year converted to unleaded fuel. That leaves aviation’s small demand (avgas is about one-tenth of one percent of U.S. mogas production, and even less in the rest of the world) to support the sole remaining Octel TEL plant in Liverpool, England. The lead plant’s owner emerged from bankruptcy a few years back. But environmental pressures on that plant continue, bringing into question the long-term feasibility of its business plan. At the moment, though, Octel claims it will provide TEL for avgas blenders as long as there is demand.
These continuing threats require action on the part of the FAA, the aviation industry, and aircraft owners. The recent FAA round table meeting was another step in that process.
At the meeting, it became clear that the term “fleet wide solution,” which is now commonly used, is causing confusion. Many understand that GAMI and Swift Fuels are on track to provide a fleet wide solution, as both claim that their 100UL fuels will, at some point, be FAA-approved for every aircraft and engine in the piston-engine fleet. However, both are pursuing their approvals by getting supplemental type certificates (STCs) for each combination of airframe and engine, which is not how the transition to an unleaded fuel was originally expected. The FAA had instead planned for candidate fuels to go through a series of tests overseen by the agency and with oversight from others in the industry through the Piston Aviation Fuels Initiative (PAFI) process. Both GAMI and Swift elected to have their fuels approved outside the PAFI process.

At the round table, FAA Executive Director for Aircraft Certification Service Earl Lawrence explained that “technically” it would be possible for the FAA to approve the STC candidates from GAMI or Swift as that fleet wide solution. But, administratively, the FAA has never made an approval like that, and it could take years to work out the regulatory process by which such a determination might be made. So even if someone makes a fuel that is FAA approved for every aircraft and engine in the fleet, you can’t call it a “fleet wide solution” because that term only applies to fuels approved via a specific process. The confusion is likely to continue, as both GAMI and Swift refer to their fuels as fleet wide solutions, without the FAA quotation marks.


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