Going Direct: Ready for Rehab? GA‘s Unseemly Addiction to Low-Lead Avgas

One thing that doesn't make the list of things most pilots hate about GA is our contribution of lead to the environment. The use of just a tad of lead in our avgas is the leading contributor of lead to the environment, but given the relatively small size of the GA fleet, we don't take much heat for it.

Which is a good thing, because there aren't any good options available just yet. In a very real way, we are addicted to 100LL.

I'm halfway joking, of course, because none of us want to use the stuff. It's expensive, it costs a lot and then there's the price of it. If it cost a buck a gallon, we'd all want to wrap our arms around it and give it a big hug, but for now, it's the thing standing between us and really affordable flying. I know, I know. If you can't stand the heat, stay out of the engine block, but as much as many of us are ready and willing to pony up the dough for 60 gallons of $5 or $6 fuel for a one-way leg in a Skylane to somewhere cool, the "able" part of the equation is missing. For a lot of pilots, spending four hundred bucks for a trip that's 300 miles out and 300 miles back seems like a lot. And if it seems like a lot to an airplane owner, then by definition it is a lot.

The problem is that there are few options.

Electric power is the Holy Grail. If it were here today as a viable replacement for avgas or Jet-A burning engines, those electric motors would be flying off the shelves. But they're not here and they're not really even close.

The other savior technology is diesel, and I'm a fan of diesel. Diesel aero engines are fuel efficient, quiet and cheaper to put fuel into because they use less of it and because you can put cheaper fuel into most of them. That 600-mile round trip referenced before in a diesel-powered Skylane would be about half the price for fuel, again, because it'll burn a lot less fuel along the way and because they fuel could be cheaper, especially if the engines were approved to use diesel and not Jet-A only.

But diesels haven't caught on because the engines themselves are expensive, a lot more expensive than the gas piston engines they replace, and when you work in the cost of the retrofitting, they're hard to justify. This fact is being blamed for the slow sales that some assay is the reason Textron Aviation's decision to discontinue its Skyhawk 172 JT-A program. (You can still get the same basic plane with the Continental diesel engine installed by STC after the fact, an option few are likely to ask for, though.

The conclusion is that we'll be sticking with our conventional aero engines for a while but putting unleaded fuel in them, if there winds up being a commercially viable and affordable 100UL out there.

That is a far bigger "if" than it was just a few months ago. In June the FAA announced that it was pushing back the date for its approval of a 100 LL replacement after it found there were too many differences between the two candidate fuels, from Shell and Swift, and 100LL. What this means is anybody's guess because the FAA has offered no details. But it presumably means that coming up with a plug and play fuel won't be as easy as we'd all hoped, though none of this almost decade long program has been easy.

What remains to be seen is how available those 100LL replacement fuels will be and how much they'll cost. Will they be cheaper than 100LL? With all the investment that will need to be put into development and production and delivery, it's hard to see how they could be anything but substantially more expensive at the pump than 100LL. Though I hope I'm wrong about that. Because 100LL is going away soon, and we're definitely going to need a new fuel to do our avgas thing.