Back in August 2021, fuel stations in Algeria finally stopped dispensing leaded gasoline. The nation was the last in the world to fuel cars with leaded gas. Here in the United States, the EPA banned leaded gasoline in 1996, and unleaded fuel was already widely available as early as 1975. With Algeria catching up, it means that no matter where you are in the world, you can rest easy knowing that the car in front of you isn’t spewing out lead. Since then, there’s been one key place where you could still be exposed to lead emitted from a vehicle, and it’s right above your head. According to the Federal Aviation Administration, there are approximately 167,000 aircraft in the United States that run on leaded avgas. That number bumps up to 230,000 aircraft if you include the rest of the world. These aircraft include everything from trainer Cessnas to small commercial aircraft and they burn 150 to 175 million gallons of leaded fuel every year. There are different grades of avgas, and the most popular one that you’ll find in the United States is 100LL, or 100 low-lead.
Why Planes Still Burn Leaded Fuel
The EPA says that while airborne lead emissions have dropped 99 percent since 1980, airplanes remain the largest source of remaining airborne lead emissions. Breathing in lead emissions can have detrimental impacts to the human body ranging from nervous system, cardiovascular system, and immune system damage to learning problems and a lower IQ in children. Lead is also absorbed by plants and the ground. There is no known safe level of lead exposure. These effects have been known for a long time. Yet, when leaded fuel got banned in 1996, the general aviation fleet got an exemption. Why? The FAA says that it comes down to aircraft engines requiring high octane fuel to reduce knocking, and Tetraethyl Lead is an effective way of boosting octane: And lead isn’t just bad for the human body, it can be bad for engines. If you don’t use a proper engine operating technique, lead can build up and foul spark plugs. [Tetraethyl Lead] is an organic compound that contains lead and, in small quantities, is very effective in boosting octane. The ban of TEL in automobile gas was phased in over a number of years and was largely completed by 1986 and resulted in significant reductions of lead emissions to the environment. TEL was has not yet been banned for use in avgas, because no operationally safe alternative is currently available. There has been an effort to replace leaded avgas for decades, and there has been some development. Some aircraft can run Mogas, which is gasoline meant for cars. However, this fuel doesn’t meet the specifications for many aircraft engines. And as AVWeb’s Paul Bertorelli mentions in his excellent history on leaded avgas, Mogas can have ethanol in it. Ethanol is hydroscopic, which means that it collects water and thus, can result in phase separation. Sucking up watery fuel in your motorcycle is annoying, but ultimately, there aren’t thousands of feet between you and the ground like you’d have in a plane. So running gas meant for a car isn’t the perfect solution. In Bertorelli’s history, he also notes that some companies have offered hardware modifications to allow aircraft to run unleaded fuel. However, these have often been expensive and haven’t found market penetration. Thus, the search for the universal solution continued. If you have the time, watch Bertorelli’s video and its sequel, they’re really good:
What Regulators Want To Do About Leaded Avgas
In 2011, the FAA started an unleaded avgas transition aviation rulemaking committee. It resulted in the 2014 Piston Aviation Fuel Initiative, combining the world’s fuel producers and the aviation industry to find a universal solution out of leaded avgas. A major sticking point in the FAA’s effort was to find a single fuel that can replace leaded fuel without modifying the aircraft. However, as Bertorelli and a Popular Science report point out, the world’s fuel producers seem to have little motivation to spend development money on something like this. Avgas is one-tenth of one percent of what the fuel companies sell for cars. And while avgas has a good profit margin, PAFI asks the fuel producers to invest into a fuel with dwindling sales over decades. Of course, keep in mind that leaded fuel is still legal, so nothing is forcing a company to develop unleaded Avgas. The FAA established a deadline of 2018 for PAFI partners to find a 100LL replacement, yet that never happened.
An Unleaded Fuel For Every Plane
Thankfully, that hasn’t stopped some companies from pushing forward, anyway. Swift Fuels has developed its UL94, an unleaded fuel that could be used in more than half of general aviation aircraft without modification. And on September 1, the FAA approved supplemental type certificates (STCs) for a drop-in fuel that can finally solve this lead problem. General Aviation Modifications Inc. has certified G100UL, a 100-octane unleaded avgas that can be used in all piston general aviation aircraft without modification. The decades-long dream of eliminating lead is finally getting realized. This fuel has been in development for more than 12 years and GAMI’s first certificate for the fuel were approved in 2021. As AVWeb reports, the certification of this fuel has been a bit controversial, with the FAA delaying approval of the fuel more than once. Unleaded fuel for every general aviation aircraft is finally here. And getting it is pretty easy. GAMI says that you’ll be able to buy a supplemental type certificate from its website, then you’ll be good to go to fuel up on GAMI’s unleaded fuel wherever you find it. But don’t expect to buy it at your local airport today. GAMI says that it needs to ramp up production and set up distribution. This could take a while and for some time, GAMI admits that its fuel may cost more than 100LL. But the goal is to get the price down to parity.
The EPA Proposes That Lead Emissions Are Bad For You (Obviously)
At the same time, the EPA has published a proposed version its very long-awaited endangerment finding. Environmental groups, physicians, and governments have been asking for an endangerment finding since 2006, and have even accused the regulator of dragging its feet on researching the effects of airborne lead. But finally, a proposed endangerment finding has been published to the Federal Register, and it doesn’t reveal anything surprising: The EPA covers a lot in its 98-page document, and there are a few things worth noting in it. One is the EPA’s estimate that since 1930, America’s general aviation fleet has burned 38.6 billion gallons of fuel, and have emitted 113,000 tons of lead into the air. Those numbers exclude emissions from military aircraft. The most recent data quoted by EPA estimates that 470 tons of lead were emitted by planes in 2017. That data also goes on to note that aircraft emissions for 2017 made up for 70 percent of the total U.S. lead inventory. The EPA’s proposed endangerment finding quotes a number of studies. These studies have found that airborne lead can contaminate vegetables, and thus offer a pathway of exposure to people. Meanwhile, other studies noted by the EPA have found that levels of airborne lead are higher near airports, and that the blood lead levels of children who live close to airports are higher.
What Happens Next
The important part about this is that when the proposed endangerment finding becomes finalized, it becomes fuel for the EPA to phase out leaded avgas: It’s unclear how long it’ll take to see a ban on leaded avgas, but it is clear that leaded avgas is now living on borrowed time. Two airports in California have already banned leaded fuel. With GAMI’s drop-in replacement for leaded fuel and this proposed endangerment finding, regulators have the tools that they need to force lead out once and for all. Hopefully, soon enough, pilots can still fly their planes and nobody will breathe in lead emissions from those aircraft. I looked up the compression on a Lycoming O-360; a textbook example of a general aviation motor, they power the Cessna 172. They make up to 220HP, though the average is around 180HP out of the 360 cubic inch 6 cylinder motor. That’s not a lot of power, but when one considers that is only ~2700 RPM, that’s somewhat impressive! The specs also list a compression of 8.5:1… That’s so low that I’m fairly certain nothing that is naturally aspirated (besides maybe a Harley) has been sold for the roads in the US since the 80s with that low of a compression ratio. Is it because the planes are running a crap load of advance at takeoff (not actually sure on that one, just a guess) on WOT with less airflow because they’re moving slowly, thus the lead is preventing knock at that precise moment, otherwise the lead is unnecessary? 8.5:1 is pretty low compression for an ICE motor, and granted, while it is air cooled motor, and also knowing that the compression is lower to keep the power pulses from destroying the propeller, why is the lead actually needed? Any aeronautical power train engineers around that could explain? Anyone want to take any bets on 10 years? 15? 10-15 years sounds about right for the whole process. Hopefully GAMI ramps up production faster than that and by the time the final rule making happens, it is a non-issue since everyone switched already. The EPA has been talking about making an endangerment finding for decades, and has basically just been waiting for an alternative fuel to be available. G100UL isn’t at the pumps yet, but should be soon. Gas is bad! But we won’t close the loophole that makes SUVs and trucks cheaper than making coupse and sedans and paying fines for lower fleet averages! I’m feeling so cynical today. MALA! Make America Lead Again! I live in the footprint of a major airport and was originally intending to do food farming in the backyard area but… the more I think about it, indoor hydroponics may be the way to go… Outdoor hydroponics should be fine too (and much cheaper). Just wash your produce. You may also be able send out soil samples to your local university ag extension for testing and see if you have a problem at all. This is something I always forget exists and definitely should do. You might think, that after a 25 year phase in period that started 50 years ago and ended 25 years ago, there wouldn’t be many around, but, talking to old guys at car shows, it seems there actually are a lot people out there who are still putting a lead substitute additive in the tank with each fill up. Always seemed like that would be a really annoying hassle to me, if this means those folks could buy gas that’s already blended to work straight from the pump, I could seem them jumping on it. It probably won’t even make the top 10 list of unnecessary things some old car guys insist on doing. It could be a good fit for those older muscle cars with high compression engines that need high octane but there are already no lead racing fuels available for that niche. Also, good report on leaded avgas. https://www.amazon.com/Red-Line-60202-Lead-Substitute/dp/B000A8FJ12 https://www.hippo-deals.com/products-images/1500/3182531.jpg As I was reading I kept thinking about lead levels close to these small airports, and then near the end “other studies noted by the EPA have found that levels of airborne lead are higher near airports.” I wonder how much higher the concentrations are, and what contributing factors (climate, population density, vegetation, humidity, etc., etc.) may make it better or worse. I do wonder, however, how many farmers still use crop dusters versus a sprayer attachment on the John Deere. I’m sure flying reduces time tremendously, but at the cost of either hiring someone to do it or getting a pilot’s license and maintaining a plane. I’d guess in the past a lot of those duster pilots were ex military so they were already licenced and trained for that kind of flying. Especially those who sprayed Agent Orange. Dunno how much the maintenance cost, I imagine that depended a lot on the vintage of the plane. It’ll be interesting to see if drone dusters become more of a thing for smaller-scale agriculture, since they have the time saving benefits of a traditional crop duster for very little training and money. Investment, maintenance and “fuel” costs on an electric drone are basically negligible, you can map the aircraft to fly itself around your field to the point where the pilot is a glorified lookout, and having taken the Part 107 exam I’m confident that anyone remotely competent enough to work on a farm could pass it while half asleep, since the test mostly comprises questions about maps and weather. I was really impressed how in the second Pixar’s “Planes” movie they did a fairly accurate fly thru of Crophopper’s turbine engine to his gearbox as it failed. The plane needs a paperwork only STC to satisfy the FAA, but no hardware changes are needed on the aircraft side.
