A new study from the National Academies of Sciences, Engineering, and Medicine on getting the lead out of general aviation fuel gave me a sense of deja vu.
Sponsored by the U.S. Dept. of Transportation, the study found that getting rid of lead in avgas was going to be difficult and maybe we should push an unleaded 94 octane fuel along with the 100LL now on the market.
The push for unleaded avgas started in the 1980s with the issuing of STCs for mogas by the Experimental Aircraft Association (EAA) and Petersen Aviation. This was more for cost and reduced spark plug fouling in 80/87 engines.
Then in the early 1990s, there was a call for the removal of lead from all avgas because of environmental concerns. During that time, I met with engine manufacturers, engine rebuilders, and many officials from many organizations like the FAA, EAA, ASTM, etc.
The prevailing opinion of the real experts was that an unleaded avgas that would meet the anti-knock performance equal to 100LL was not possible at that time using the known technology — and certainly not at a reasonable price.
There were also safety and performance concerns like exhaust valve recession that needed to be addressed.
But the FAA, Environmental Protection Agency, and a bunch of other industry “leaders” formed a committee to develop a 100 lean rating avgas.
Having a single dimension goal like a 100 lean rating is like a professional football coach who observes that most successful offensive lineman weigh over 300 pounds. So, he figures that any man who weighs over 300 pounds should be a good lineman. Unfortunately, it does not work that way.
This whole process was further derailed by Swift Fuels announcing it had an unleaded fuel that would out-perform 100LL and cost less to produce. A fuel never materialized that came close to meeting the claimed performance.
But the committee pushed on with a number of other candidates and millions of dollars in testing and development costs. Where are we almost 30 years later? Basically, in the same place, with a government funded study telling us we are in the same place.
Why could the industry develop leaded avgas in a few short years during World War II and not do the same for an unleaded fuel utilizing all of the knowledge gained over the last 70-plus years?
During the war effort, most of the people at the Shell lab were working on the project and we had a large number of combustion scientists. Now we have scientists working on producing more fuel at a lower cost.
The same is true for the engine manufacturers who do not have engineers working on new engine designs, but rather working on keeping 70- to 80-year-old engine designs working.
Another sticking point is social media and the Internet. There is a lot of misinformation or non-substantiated information online. For example, several years ago, I attended EAA AirVenture Oshkosh and asked most of the knowledgeable engine people if they had noted any exhaust valve recession cases for people who were using just unleaded mogas from the start. All of them had examples of recession on new or just overhauled engines.
I wrote this up in a column and got a great deal of negative feedback. Most of the comments came from people who had “read on the Internet” that someone somewhere had gone to full TBO using only unleaded fuel.
But the problem isn’t social media. The problem is we are still using 70- or 80-year-old engines that were designed for — and only possible because of — high octane leaded fuels.
In the automotive world, all of the engines have been redesigned to run on unleaded fuel because of catalytic converters. Modern cars have liquid cooling, knock sensors, electronic fuel injection, and on and on. When is the last time you saw a carburetor equipped air-cooled car roll off the assembly line in the USA?
So what’s next?
One possibility is a plan suggested 30 years ago of promoting a 94ish unleaded fuel, while continuing to produce 100LL. Another option is to introduce a 100UL fuel that does not meet the requirements of many aircraft in the general aviation fleet and let the planes fall where they may. (Have I mentioned the liability problems with a new fuel?).
Or we can continue the current process and have another study released in another 30 years and see how much progress has been made.
The ones has to be on plane users to not cause lead polluters, and deal with it (new engines, going electric, not flying whatever), and for everyone else to suffer even a little heavy metal toxic pollution like this. Aviation industry- deal with it…governments – ban all lead, NOW
1969 Corvair? Try almost every vehicle up to AT LEAST the very late 1980’s!
“When is the last time you saw a carburetor equipped air-cooled car roll off the assembly line in the USA? ”
1969 Chevrolet Corvair
Finding an alternative fuel only perpetrates keeping GA in the dark ages. My C172 has a flex fuel engine and can even burn AVGAS ( but you have to do an engine run up, and more frequently check spark plugs and change oil). It cost me 60% less to fly than original O-320, has no carb heat or mixture, and starts up with a push of the start button regardless of temperature while well out performing any C172 model.
Check out corsairpower.com or RobinsonV8 or other new designs, these type of new engine alternatives maybe a better solution for keeping the old fleet flying rather than simply spending millions on band aids.
I encourage people to check out https://savereidhillview.org/UL94Advantages.pdf for a different perspective on GA fuel or to actually read the NAS (National Academy of Sciences) report on unleaded GA development progress at https://www.nap.edu/read/26050/chapter/1 ; the NAS report is a little lengthy at 128 pages but does a great job of covering the topic. The UL94Advantages.pdf is a presentation done in January, hosted by the FAA, on unleaded fuel, the issues with mogas, and the challenges with UL100; quite a bit of information in it comes from the NAS report.
Getting to 100UL is very possible, but it isn’t easy. While cars have an average life of probably 10 years (or less) and there are nearly 100 million cars built every year, GA aircraft are approaching 50 years of age on average and there are only a few hundred that are built each year. Therefore, you need to build for the existing fleet, since it would otherwise take years to replace. When you look at 50 year old aircraft, many of the manufacturers are no longer around, which puts the onus on the FAA to check and approve things; they are abundantly cautious and have never approved or chosen a new fuel before, I believe.
Add economic realities that the fuel companies face. Motor gas volumes are 367kk gallons per day; Jet-A is 65kk gallons per day; Avgas is 435k gallons/day (source: https://www.eia.gov/dnav/pet/PET_SUM_MKT_DCU_NUS_A.htm) . When the volumes are 2-3 orders of magnitude smaller, you don’t get the big focus.
I think this article’s critique of 100UL and UL94 is unfair, and frankly uninformed, and comments with respect to “letting the airplanes fall where they may” are a huge disservice that promote fear without evidence or justification. I give the FAA (and fuel companies) credit for trying to solve a difficult problem, insuring that GA is safe, and preserving the value of our investment in aviation and our aircraft.
I’m also optimistic that the solution is largely solved for many aircraft with UL94 (disclosure: I’m trying to bring to our RHV airport in northern CA) and that UL100 has a good chance of being approved within the Biden administration. (My own personal opinion: I don’t think it is a coincidence that the NAS report was released at the beginning of this new administration.)
Here is one more link providing another example of the detailed analysis that the FAA is doing on these fuels http://www.tc.faa.gov/its/worldpac/techrpt/tc14-11.pdf It is another report showing that the UL fuel options are good for many aircraft out there.
Personally, I wouldn’t exclude an electric future.
Prices of batteries are coming down, capacity is increasing, charge time is coming down, cost is coming down, weight is coming down. All the major car companies are going electric as well.
I’m looking at my Cessna 150. Almost 500 pounds of the 1,600 pound MTOW is the gasoline engine and all the parts needed to make it work, monitor it, control it, fuel it, and so on. The engine itself is 220 pounds or so, 38 gallons of fuel is 228 more.
If a 125 hp electric motor weighs 100 lbs (and these can be bought now), that leaves me 350-ish pounds for the batteries. I just happen to have these two big spaces in the wings where the fuel tanks came out.
At this point I expect to hear whining about eventual battery replacement costs. We already have (or should have) engine reserves for the inevitable major overhaul on our gasoline engines, so that excuse won’t fly. Remember, battery costs are coming down (and capacities are going up), so in seven or eight years, I’ll get more range at a lower cost when it becomes battery time.
There’s also much less pollution. A professionally managed power plant makes FAR less pollution than a fleet of indifferently maintained individual vehicles.
So – cost equivalence coming soon, no noise, no flammable fuels to splash around in an accident, no vibration, no oil changes or oil leaks, no carbon monoxide, no loss of power with altitude (other than propeller efficiency), “instant on”, the motor will go 50,000 hours, then you just change two bearings and you’re good for another 50,000 hours, no more fuel tanks at FBOs, or fuel trucks, or pipelines, and no more EPA waiting to fine me a bazillion dollars for a few drops of fuel dripping on the ramp. And absolutely zero lead.
If I could buy this conversion kit today, I’m ready to write a check NOW. I’d be willing to bet that in five to ten years, this will be a reality, and a few years later it will also be possible for bigger, faster airplanes as well. Someone is already flying an electric conversion Caravan, and there’s an electric conversion 172 prototype as well. Pipistrel makes an electric two seat trainer. This is coming . . .
We can side-step the entire problem of no-lead aviation fuel entirely by changing the direction towards electrification. I don’t care if my airplane is powered by electricity or pixie dust as long as it flies. Gasoline is going away, by 2040 (according to DOT) half the cars on the road will be electric. Airplanes shouldn’t be left behind.
Give me an O-200A and a tank of red gas any day!
Well that’s what i have right now (except the contents of the tank are blue, or clear when I can buy non-ethanol gas), but I’m just planning ahead if the availability of gasoline goes away and/or the price gets ridiculous.
O-200A is a good engine, but it is REALLY old technology, and we can do a lot better nowadays. I’ve been flying behind mine since 1982, but parts are getting stupid expensive. $800 for a magneto gear? Dang!
I hear you! My trouble back in the mid ’70’s when 80/87 went away was low compression on the O-200 due to burned intake valves when using 100. About every 200 hours, it was at LEAST one jug per engine that I had to dress the seat and replace the valve, and you can only dress the seats so many times. It became ritual. Then there was the Lycoming O-235-L2C, which is a technical term for JUNK!
I fly behind a GO-300, which is 1-1/2 O-200’s.
Leaning aggressively all the time, except climbs, and the plugs are clean, no lead balls.
I’ve found that the Tempest plugs made a huge difference in running lean, and reducing fuel burn.!
Lithium-ion battery has energy density by mass of 0.4 to 0.9 MJ/kg and by volume of 1 to 2.6 MJ/L, whereas avgas (100LL) has energy density by mass of 44 MJ/kg and by volume of 32 MJ/L. This means that you need roughly 44x (44/0.9) more weight with batteries to achieve the same amount of energy, or about 12x (32/2.6) more volume.
If you want to achieve the same performance as you do now, your gas will weigh 44x more and your fuel tank will be 12x larger (and you WON’T get the performance you do now). Of course, new aircraft are being developed that can use batteries (eg, training aircraft operating around an airport) and there are hybrid aircraft that are being developed. (See Pipistrel and Ampaire EEL, respectively). And then you have companies like Jobe that are doing electric airtaxi programs.
And while cars may go electric, they don’t suffer from weight issues like a/c do. And while batteries will improve, the orders of magnitude described above (44x and 12x) will take a while.
I’m very bullish on electric a/c, but not as a retrofit.
With 350 pounds of batteries, using the Tesla battery data, 85 kwhr and 1,200 pounds, that is about 25 kWhrs.
A 100 hp motor will use 75 kwhr, which gives about 20 minutes of use…..maybe 40 minutes if you ‘throttle’ back immediately after lift off.
Oh, and in a crash, folks will have to worry about the 480 volts electrocution danger.
The C152 I flew had 23 gallons usable and at 6 gph, that’s 3.8 hours.!
I’ll take the gas over a low energy density battery.!
Gasoline will be here long after I’m gone…
I’m with you until the last drop of gas!
The simplest solution, is to provide alcohol free automotive fuel in lieu of AVGAS. A large majority of GA aircraft can, and did, operate fine on MOGAS, right up until they added ethanol (a dubious attempt at pollution reduction, but a boon to US farmers).
The production facilities are setup to produce this product already, in great quantities, and by simply pulling the desired produce ahead of the final blending process we should provide unleaded fuel at a reasonable cost. Couldn’t be simpler.
Alternately, it is entirely possible to remove more than 95% of the ethanol from mogas, through a relatively simple process, which could be done at the point of use, though at additional cost and work to the local airport supplies.
The Aviation Lobbies have done as much to sabotage efforts to replace 100LL as anyone and the FAA has played the same game all along as they have no interest in changing. They simply don’t want to change. A multi fuel solution works best, but most airports don’t sell enough fuel to justify the cost of maintaining and insuring multiple fuel tanks. The best single fuel solution would be to create a high octane fuel with the octane maximized via methods other than lead, then a minimal amount of lead added to bring the octane up to meet minimum standards for the engines. A TRUE Low Lead fuel! One would think valve recession should be addressable as cylinders are replaced or overhauled by the use of more modern metals as is used in the automotive industry for valves and seats. Granted, heads in air cooled aviation engines do run hotter than the heads in water cooled cars, but the automotive manufacturers fixed the valve recession problems over 40 years ago.
As much as I dislike government interference, one possible solution would be by regulation to require an unleaded fuel option for any vendor that sells Aviation Gasoline. If that were the case, airports (usually the smaller vendors) that can only afford to maintain one fuel storage tank would be selling the potentially lower performance unleaded fuel that most of us can burn. Only the larger airports with higher volume sales would continue to carry 100LL for the smaller number of high performance aircraft that require leaded fuel.
The negative fall out from that is that this would further dilute the fuel sales at the smallest vendors and potentially cause a number of airports to discontinue fuel sales. Or, it might cause a number of the small vendors to start carrying either an unleaded fuel like UL94 as a single fuel option or optionally MOGAS as a second fuel option that I believe a number of us would use. I know I would.
Realistically, any solution that comes forward will cost as much or more than the current 100LL and that will continue to drive pilots away from aviation. For me, the best solution is to continue to do nothing. I have been hauling premium Mogas in a 110 gallon tank with am electric pump in the back of my truck for decades. Unfortunately, access to uncontaminated MOGAS is not universally accessible throughout the country and the supply in a number of places is sketchy at best. I fly cross country enough that I have to buy an occasional tank of 100LL. Apparently that is enough lead to prevent valve recession, but little enough lead that I don’t have issues with excessive valve guide wear or lead build up in the spark plugs.
One last comment on the leaded fuels. Nobody ever seems to take into account the number of “mad hatter” mechanics in aviation. Aircraft mechanics that do engine work are continually exposed to lead and that leads to serious brain dysfunction, often times displayed through moodiness and forgetfulness. Most mechanics think nothing of bead blasting cylinders, or cleaning parts with a wire wheel which throws a lot of lead into the air they are breathing. They also clean parts in solvent which gives them a significant amount of exposure from the lead salts that get suspended into the solvents, then get absorbed through the skin. Mechanics that do a significant amount of piston engine work should consider being tested for lead levels in their blood and consider mitigation methods when working with lead contaminated engine parts. Leaded fuels are much more of a danger to the mechanics that work on the lead contaminated engines than it is to the general public through breathing air contaminated with a minuscule amount of exhaust from aircraft engines. I personally know some mechanics that have suffered some brain dysfunction from lead exposure and gone through chelation therapy to help reduce the amount of lead in the bloodstream with good results.
The Democrats have the power now to do their worst….they will not only ground half the fleet over leaded gas but they will start to close airports too. The climate radicals are in charge and you can bet aviation will be under their thumb quickly.
With leaded AvGas being only a few tenths of one percent of gasoline consumption in the US, something other than tetra ethyl lead is driving all this. Sounds like the Greta Thunberg syndrome to me! Beware!
In France we have UL 91 unleaded for our PA28-161.
This is a crucial issue as you can bet the new administration will soon target the removal of lead from avgas due to alleged health concerns. The general aviation lobby does not have anywhere near the level of influence needed to stave off the attack. We have a great big target on our backs and the clock is ticking.
One of the worst things I can think of that impacted aircraft engine maintenance was the phasing out of 80/87 leaded AvGas. Our flight school piled more hours on aircraft in a shorter time than “the average bear”, and the repercussions of using 100/130 became readily apparent to me. None of our 80/87 engines escaped some form of malady, and our maintenance and repair costs soared.
Remember how great the Champion “BY” plugs were when they came out? It sure took a lot longer to lead foul the extended nose on those things!
It seems very few remember the problems that the demise of 80/87 caused.
I sure hope that some alternative fuel is developed before Innospec, in England, decides, or is stopped from making TEL, since they are the only source in the World.
My old Cessna has the Peterson autogas STC to use 87 octane, but in California, it’s worthless, since all gasoline has ethanol in it.
As I’ve asked before, wouldn’t returning to MBTE in above ground tanks get us 90-93 octane unleaded ?