Unleaded Avgas Update
Some of you you may be wondering what's going on in this arena. I'll give you my two cents from the inside looking out. So you all heard the noise coming out of Oshkosh about a new UL100 fuel that was supposed to be the answer to everyone's wishes. Everyone got very excited including the pilots associations. Well, Lucy may have pulled the football away from Charlie yet again.
Here's the deal. FAA came out in November saying that the STC route will not lead to "fleet wide approval" of any fuel. What does that mean and why should you care? Well, even though the vast majority of aircraft don't need 100 octane fuel, the vast majority of the fuel consumed is by aircraft that require it. So you know where you are on the totem pole.
This new fuel is unlikely to get "fleet wide approval" from the FAA, unless and until it meets an "industry standard" meaning, until the OEMs and FAA confirm that it is suitable for fleet-wide use and it conforms to an industry standard such as an ASTM fuel specification. Problem is they haven't and likely won't, for three main reasons: 1) the owner won't let them look at it 2) the fuel would not likely pass muster, and 3) the owner has so far refused to go through the ASTM standardization process.
Why not? For several reason including:
1) It may not have have enough detonation resistance to meet the most demanding requirements pf the fleet.
2) its density is higher than 100LL
3) its cost is higher than 100LL
4) the owner has so far refused to submit the fuel for additional testing.
So where does that leave us? The Santa Clara county has announced a ban of leaded fuel starting January 1 2022, likely in the hope they can close their airports and develop the land more profitably. UL94 may work for a while if they don't have any significant traffic from turbocharged aircraft. But make no mistake; this is likely less about public health than real estate development.
The only solution is to develop an unleaded AVGAS that works for the entire fleet. Difficult? yes. Impossible, no. Today we took an important step in that direction with an unleaded fuel that meets detonation resistance in the most demanding engine in the fleet, not a turbo-normalized or inter-cooled engine, and under the most demanding POH conditions.
But it is just a step. There is a lot more testing to go. This is what is required for "fleet wide" approval and for nationwide deployment. The rest is Kabuki theater. Fortunately, your associations finally understand this.
Last edited by Clostermann : 12-17-2021 at 02:50 AM.