When I bought my little PA-23 Apache with its low compression 150 hp engines I thought this was not much of an issue. All they need is 80 octane. It’ll run on MoGas. So any of these 3 fuels could work just fine for me and the Apache. Now, my Experimental Bearhawk has a 200 hp IO-360 Lycoming and it needs 94 octane but it appears all three should be capable of that as well. So the real issue is getting something the most critical engines can use and then make it widely available.
So I think there are two big questions:
1. Can anyone make a 100 unleaded fuel that all piston engines can run on without modification. If not then what kind of modifications would have to be made and what does that do to aircraft performance?
2. Can we all use one fuel or will there be two or three fuel manufacturers that we would have to choose from. If so, can they be mixed or must they be kept separate?
For the first question I would love to know if having variable ignition timing would help. If so, I would think this would be the single easiest modification and one that may even give better overall fuel burn and/or performance. Other potential mods (water injection?) would be more complex and costly I would think.
The second question could make a huge difference in the real world. If would could have three competitors it would mean companies fighting for market share and perhaps lower prices for pilots but it could also mean not enough for each of the three to have enough volume for efficient production. If the fuels can be mixed then the idea of all three existing together looks more realistic. If I can’t mix different fuels in my tanks then everything gets way more complicated. I think only the FAA can answer that.
Any other big issues? I’m sure there are and I hope they get dealt with soon. In my opinion there has to be a third party (FAA) to check all the claims and counter-claims by each group pushing their own fuel.
The final point here is the many of the newer GA planes getting built are running on Jet-A. I think the big manufacturers could simply pivot to turbine or diesel engines that run on Jet-A and leave the rest of the GA piston fleet to sort it out ourselves. I’m not so sure but what they might actually prefer that we park all our old planes and go away or buy a new ($$$) plane.
