Unleaded Avgas: Do We Really Have To?
The integration of a new kind of aviation gasoline into the system is not something that will be easy, cheap or fun. We should put it off as long as possible.
By Robert Goyer / Published: Jun 11, 2013
The FAA the other day released a request for alternate fuels to test in what it hopes will be an accelerated adoption of an unleaded avgas into the GA fleet. It's aiming for five years. I'll bet my house that won't happen.
In any case, upon the announcement, alphabet groups rose as if as one to applaud the move by the FAA to take the initiative to do something about the 100LL problem.
It is a problem, though it is by nature far more of a political problem than an environmental one. As you hopefully know, lead in X-ray shields is good but as an additive in gasoline it is bad. The United States banned lead in auto fuel in 1995 (California did the deed in 1992), and around the world unleaded auto fuel is the rule, though you can still top off your world car with leaded goodness in Afghanistan and Myanmar.
The addition of tetraethyllead in our auto gas was intended to do two things: reduce knock and protect valves, though the valve side of the equation is probably as it turns out related to octane more than any protective qualities of the lead. Lead protects our airplanes’ engines too, something that we were able to continue with the introduction of 100LL in the early 1970s, which would ultimately replace more highly leaded aviation fuels as the only option for gas piston engines.
At the time, the adoption of a lower lead option seemed like a good idea, as it kept our engines operating — well, at least all but the deepest breathing of them — while we weaned ourselves collectively off of 80 and 100 octane more highly leaded nectar.
The problem is, here we are around 40 years later in exactly the same place we were when we made the transition, and the world has not stood still as environmental activists look for ways to further clean up the environment. When it comes to lead additives in the United States, general aviation is pretty much the only bad guy left. Our saving grace is that it’s not well known that our gasoline has lead in it. So, shhhh — don’t tell. Just kidding. (But really, don’t tell.)
The truth is, the tiny amount of lead in our avgas has a barely measurable effect on the environment, and even at that, it's not clear that avgas is the source of the lead that scientists can barely measure. There's also no demonstrably negative effects of the low levels of lead in the environment as things stand today. This is a problem largely because it's perceived as a problem.
Still, it’s only a matter of time before we’ll be forced to go lead-free, and when that time comes, we need to be prepared. The only problem is, there’s no good way to do that. The ideal answer would be a so-called “drop-in” solution, a fuel that we can just start mixing in with existing stocks and run our existing airplanes on and call it a day. That's not likely to happen.
And if it doesn’t, then the real problems begin. Some of our airplanes will run just fine on unleaded fuel, as many of them are already doing. Others won’t, and we’ll have to essentially re-certify our engines to the new fuel. Who knows how they will stand up to whatever mixtures of petrochemicals and additives we arrive at. The costs to owners could be very substantial. How substantial? We simply don’t know.
We also might be shooting ourselves in the foot in terms of infrastructure. I spoke with an FBO owner who told me the cost of adding new tanks for a new fuel could be as high as $150,000, and that new trucks would likely be needed too. With very little profit to be made selling 100LL to begin with — 13 gallons in a Skyhawk, he said, takes the same effort and infrastructure as 300 gallons in a CJ — there’d be a powerful incentive not to sell the new fuel, to keep selling Jet-A and let gas piston types go elsewhere to find their fuel. (Any wonder diesels are starting to sound like a good idea?)
So, okay, it’s clear that unleaded avgas is going to have to come one way or another, and it’s clearly in our best interest to start doing our homework on the subject now rather than later, so we can at least have a good bluff when the time comes.
But in an industry that already faces numerous challenges, any premature move to adopt an unleaded aviation fuel before we have a chance to make it workable could spell economic disaster.
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