When I started to write this post on unleaded avgas, I sat down to read about the upcoming evaluation program for four candidate fuels. The more I read the more questions it raised.
For instance, why does Swift Fuels have two candidates?
But the biggest question concerned the percentage of the piston aviation fleet that the new candidate fuels will satisfy. A few questions arise, like which engines are the most critical, under what conditions will they knock, which airframe, propeller, operating conditions are most critical, and on and on.
For example, if an engine runs knock free on a candidate fuel in a test cell in New Jersey, will it also run knock free in a hot, dry climate with a bigger prop and an overloaded aircraft?
And what about testing orphan aircraft or big radial engines? Are they going to test a 3350? If so, at what boost pressure and rpm?
What margin of safety is there? If someone is using the new fuel and has their timing advanced more than specified, will they have problems? What about exhaust valve recession in newly overhauled engines?
This is like doing an algebra test with 36 unknowns and only two equations.
Then when they determine what percentage of the planes will be satisfied by the new fuel, what do you do with that information? If they have a fuel that satisfied 99% of the fleet, how can you be sure that your plane is part of that 99%? If it isn’t, what do you do? This may sound minor, but I think this is going to be one of the biggest problems if one of these candidates ever reaches the marketplace.
Another big problem is going to be cost. The cost projections I have seen seem unrealistic. People keep saying that there will be a huge cost savings because the fuel will be able to be shipped by pipeline. There will be some cost savings, but because of the cost of the product and the small volume, the loss from the interface will limit pipeline usage to only large shipments. Most of the shipments will still be by truck or rail.
And then there is competition. If they only approve one fuel, who will be able to sell it? If they only approve one, does anyone out there believe that the company selling it will keep it at minimum cost? Or will it write a spec around the new fuel and let other companies produce the product?
And what about 100LL? Will FBOs need two fuel systems because there will be a time when the new fuel and 100LL will both be available? In the switch over, do they plan on outlawing 100LL? If the new product and 100LL are both available, will they force FBOs to handle both?
No matter how they do it, it is going to be messy.
And then there is mogas. If the new product is much more expensive or has problems, will more pilots switch over to mogas, which could reduce the volume sales of the new product to an almost uneconomic low level?
What about the storage stability of the new product? 100LL is very stable and people store it and then use it a year or even several years after it was produced. This is especially true in northern climates where the supply line is very long. Will the new product store as well or will it form gums and or take on moisture?
And the questions go on and on. For when all is said and done, much will have been said and little will have been done.