GAMI's high-octane unleaded avgas approved

Avfuel GAMI 100UL

It’s taken 11 years of hard work but General Aviation Modifications, Inc – better known as GAMI – has finally won approval from the FAA for its G100 high-octane unleaded avgas.

GAMI followed the FAA Approved Model List (AML) STC process whereby the FAA issues the initial STCs with an AML of specific aircraft and engines, and then progressively expands the AML based on additional testing and data.

In further collaboration with the FAA, GAMI will complete two additional tests to expand hugely the scope of the Approved Model List.

At that point, G100UL avgas will be a straight ‘drop-in’ replacement for 100LL for most of the GA fleet.

GAMI is working with Avfuel Corporation, a leading global supplier of aviation fuel, to work through the logistics of distributing high octane unleaded avgas. Avfuel is establishing a supply chain to responsibly bring G100UL avgas to market on a commercial scale.

GAMI anticipates G100UL avgas supply will meet North America’s demand for high octane aviation gasoline within the next four years.

G100UL avgas can be mixed with 100LL in any proportion, and is compatible with the existing fuel infrastructure without modification.

Tim Roehl, GAMI president, said, “The FAA approval of G100UL high octane unleaded avgas is a truly huge development for the future of general aviation!

“GAMI and all of its employees have dedicated themselves to this project for over a decade. Now is the time for all of the stakeholders in the general aviation community to stand up and celebrate.

“These AML-STCs are the ‘beginning of the end’ for the continued use of lead in aviation gasoline.”


See 4 comments


  • Ashok says:

    This sure is a gamechanger and is great news for us Rotax powered folks. Can’t wait to have this widely available all across the UK.

    • Roger O'Donnell says:

      Have you heard of UL91? Its already available at a lot of airfields is lead free and works on the majority of the GA fleet.

      • Jonathan Briggs says:

        I think why this is a game changer is that airfields don’t need to stock 2 types of avgas anymore. The G100UL is a complete replacement for 100LL in the entire GA fleet, including war birds.

  • Yes, UL91 will suit most petrol engines but its uptake is, presently, limited.
    The problem is the engines that can, currently, only operate on 100LL. Just lowering the compression ratio on these engines opens up a whole new vista of expensive STCs and, with the accompanying power loss, how will out of production aircraft fare in the process?
    Whilst this latest entry into the 100UL market is welcome, what are the prospects of having the aromatics approved outside of the US? And, if approved, what is the likely cost of this niche fuel if imported?
    For buyers, the message is clear: either a petrol engine that is certified for 91UL or a diesel engine. For existing owners of engines that require 100LL, the future remains obscured.

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