The uphill battle of unleaded avgas leaves both the main players in the industry and the regulators themselves looking bad—but in a banal kinda way.
I enjoy AVWeb on YT for AV news (really, I just enjoy the humor/personality of Paul Bertorelli lol), here are a few insightful videos that summarize the story:
Didn't they just legalize unleaded avgas very recently? After a multi-decade regulatory review process?
Seems odd that they were so hesitant to legalize it and now that they did, it becomes the only option!
They don't "need" lead any more than pre-70s cars "need" lead. They were designed to run on leaded fuel, but there are lead replacement additives which are able to fulfill the same technical requirements. TEL is just cheap, effective, and well understood for legacy applications. It isn't the only option to boost octane, by far.
The only issue I had on my 240z was the valve seats were some super soft brass like material, those needed to be swapped as they were beat to up and did not seal. The 75+ heads, all have steel seats.
I’ve actually never experienced the, “California gas sucks” issue that car people from the mid-west talk about, have never had an issue with it. ¯\_(ツ)_/¯
Maybe my understanding is incomplete, but AFAIK the "California gas sucks" thing is just because the highest grade you can find at most pumps there is 91, while we get 93 in a lot of other states
Not that it matters when everything made for "premium" is tuned for 91 from the factory anyway, not 93
California actually has different gas that produces fewer emissions - it's part of the reason gas is more expensive here. It's called CARBOB grade, c.f. RBOB/CBOB.
They are, however, manuals and documentation for US market vehicles will be specified in AKI (aka '(R+M)/2') regardless of who manufactured them. Some manuals also specify both AKI and RON, and that can be a source of confusion.
I'm in Europe and here it would be "98 recommended, 95 allowed with possible degradation in performance", as it's the case for my 2006 car. More modern small volume turbocharged engines should be even more sensitive to octane number due to higher compression ratios than common American engines of twice the volume for the same horsepower. The engine ECU will reduce boost pressure and fuel charge based on feedback from the knock sensor.
California 'gas sucks' for a couple reasons which are easy to miss if you're in California.
1) Few refineries make it, so it's MUCH more expensive. But if you're living in California, it is easy to miss because EVERYTHING is much more expensive.
2) Mileage is generally poorer, due to the mandatory ethanol mixes. But some places also usually mix in ethanol, and the difference is usually in the 10-15% range. So unless you have a good A/B comparison going, it's also easy for it to blend in with all the stop and go driving, and terrible road conditions.
3) Mandatory Ethanol means generally very poor storage characteristics. Which considering how much driving happens in California (and how dry the climate is in the populated areas), most people won't notice.
So does it suck? Comparatively, definitely! Is it likely to be noticed unless you're very aware and have experience with other options? Nope.
I understand that additionally in some vehicles (not necessarily aircraft) predating ethanol dilution the evap systems may begin to malfunction at high elevation and temperature due to the lower initial boiling point of ethanol.
In the case of my vehicle it results in low/rough idle and positive fuel tank pressure which otherwise do not occur either at lower elevation or with ethanol-free fuel at elevation.
Once you've replaced those valve seats with hardened ones, you don't have to worry about adding lead substitute in every fill up. You do still have to worry about getting the right oil additives though, as the old flat tappet engines need more zinc than modern oil blends have in them. Ethanol in the gas is also a concern, but any conscientious classic car owner has hopefully replaced all the rubber and plastic bits in the fuel system to ethanol safe ones.
I think (don't really know) alloy steel valves and hardened seat were pioneered by the aircraft industry and appeared in cars by the 1950's. So really lead wasn't needed to extend the life of valves after that. Also my experience with some shitty 1960's cars was the valve guides would wear out before the seats. Compression is fine but engine burns oil and fouls the plugs. You could see it with older cars when going downhill, they'd be blowing oil smoke.
No idea about 240z specifically, but at least things designed for sustained high performance (like aero engines) tend to use valve seats made from some wear and temperature resistant alloy like stellite or brightray.
Legally, they need to run a fuel which is approved on the type certificate data sheet for their engine (and the engine-airframe combination).
The recently developed G100UL unleaded fuel requires a change to the type certificate of the airplane (by serial number) and engine(s) (by serial number) to be legal.
Until that supplemental type certificate existed, these airplanes did legally need leaded fuel.
No, G100UL is a full drop in replacement that meets the standards off AVGAS which is what is required by the certificate. Fully legal on all engines with no change to the certificate.
It does not meet the composition standard of 100LL, which is why you need to buy an STC (Supplemental Type Certificate) from GAMI to use it legally in an aircraft. (It is a drop in replacement from a performance point of view, but does not meet the original type certificate fuel standard.)
I would imagine that the gelling problems ethanol can sometimes cause in automobiles is magnified when used for aircraft due to the thermal dynamics present in aviation (the temperature drop while in-flight) that aren’t a factor for most automobiles. That’s just my intuition, I’m sure there are better informed people here who know better.
Yup, also, there are specific chemistries used in some composite wet-wing designs that can be damaged by ethanol. It's the final reason I became less interested in the DarkAero 1 while following its development.
That's part of it. Ethanol is incompatible with materials commonly found in airplane fuel systems.
Another aspect is that many piston airplane engines need high octane because they have relatively high compression ratios: WWII era engines need 130 octane to develop full horsepower (they can be operated at reduced manifold pressure on currently available 100 low-lead gas), and even many post-war civilian engines require 100 octane.
Still another aspect is that the FAA is relatively conservative and doesn't want to approve something that might lead to, for example, vapor lock or fuel freezing issues.
>airplane engines need high octane because they have relatively high compression ratios: WWII era engines need 130 octane to develop full horsepower
I mean, high octane and compression relative to other 1960s engines. The common engines in nearly any single prop cessna have about a 9:1 compression ratio, which was massive back when it was built, but laughably bad compared to anything manufactured after the advent of Fuel injection and better piston geometry.
Modern cars regularly have over 12-1 compression ratios on 87 octane.
1960s era carbs and top ends were just abysmal and did a terrible job of mixing the fuel and air charge and controlling the flame front, because we just didn't have the kinds of computer controls and fluid dynamic simulations we have now, to dynamically prevent knock.
Rotax engines are modern and can reach identical performance figures or better, with the same weight or lighter, simply by using modern techniques like fuel injection or a small turbocharger. They do this while running on 91 octane
Except none of that can be used until someone goes through the millions of dollars to do all the design work, safety testing, and mountains of FAA paperwork. Oh, and take on the liability of a mistake killing a bunch of people.
In the mean time, rebuilds have to meet the existing design. Which has specific standards.
It's not like Cessnas themselves can't be wildly improved on in general!
As an old Boeing engineer friend of mine used to say 'when the weight of the paperwork exceeds the gross weight of the plane, it will fly.'.
1) Regulations (vehicle fuel comes from sources/supply chains generally not willing to do the paperwork)
2) Lack of solid quality control relative to aviation fuels (see #1)
3) Power to weight ratio matters a LOT in aviation, and aviation engines run at typically far higher elevations for at least part of their flight time. So aircraft engines generally push things harder, have higher compression, and can be damaged more easily with 'junk' or contaminants.
From memory octane levels have a huge bearing on engine performance and that affects take off distance. Aviation has had a much higher octane rating than your typical car gas.
Sure, and any petrol engine can run on 78 RON fuel to. It's just that if you try to run it at full power you'll blow it up. Wee bit of a problem on takeoff.
Same thing with running certain large piston airplane engines on 100. They blow up.
> There are several options that involve no lead, generally substituting with ethanol
Ethanol is corrosive to aluminum. Thankfully airplane designers have never used aluminum in airplanes...
We can't use ethanol because of phase separation amongst other reasons but this is true considering we've been using stuff like toluene probably even longer than tel.
Yes, but it's not currently legal to use in anything.
You still have to apply for and buy an STC for your specific airframe's serial number and engine's serial number. Then you have to add some paperwork to the logbook and POH and add placards to the fuel fillers and cockpit.
In theory you should be able to automatically get it for anything which was approved from the factory to use 100LL, but the STC application form (here: https://stc.g100ul.com/aircraft/) does not allow you to select most mid-century large radials (which were usually originally certified on 130) or the airplanes they were installed on.
To be clear, this is a great thing, but you can't legally just fill G100UL in any random airplane.
Exactly. Remove the STC requirement. If the fuel is unreliable that it won’t work in every 100LL aircraft, then it shouldn’t be forced upon us. If it is completely safe, then an STC should be unnecessary.
What about something in-between? The fuel is reliable in almost every design, but there's some design out there that -relies- upon lead depositing to engine surfaces to be reliable (as opposed to the octane effect).
I don't think it needs to work in every conceivable 100LL aircraft: just almost all. Every is a high bar.
You can’t realistically support both leaded and unleaded avgas, and this is why adoption is so low.
Airports don’t always have the space for a second avgas tank (if this is the in between option), and if they did don’t necessarily want to spend money on setting up that infrastructure. So the current catch-all is to provide leaded which is cheaper and guaranteed to work in everything.
I think it’s great we are getting this forced through - it will make the approval process streamlined (like loda was) and removes a major reason people used to push airport shutdowns.
> Airports don’t always have the space for a second avgas tank (if this is the in between option), and if they did don’t necessarily want to spend money on setting up that infrastructure.
Lots of airports are owned or regulated by local governments which might want to move that single tank to just unleaded. E.g. Santa Clara County banned 100LL at local airports.
Forklift upgrades suck, too. You're best off getting some of the way along and then forklift. Arguably we're reaching that point.
Which is why it is taking so long. Because if an engine grenades on takeoff, it's almost guaranteed to kill someone. If that was because of the fuel switch, that's a real problem.
What's the FAA incentive to change the type certification (and STC) rules here? There's a perfectly workable STC path, that's not even that expensive [almost rounds to $0 in the scope of private aircraft ownership expenses).
The TC says you must run 100LL. The STC says you can freely mix G100UL in any ratio. The legal/certification problem is solved.
The beauty of G100UL is you just need an STC - just paperwork - to be legal with GA aircraft. All gasoline powered aircraft and engines in the FAA’s type certificate database are covered by the STC for G100UL... which is amazing.
I'll be doing it, as soon as our home base carries it for my 56 o200.
Can't upvote this enough. This is going to kill small operators that might not be able to comply. Why not just let the leaded fuel users die from attrition naturally?
Because pollution is an externality cost that the market does not take into account. The only way to solve it is with regulation. These regulations are justified on the basis that it is wrong to poison others, or pollute their right to shared public resources.
Regulation does not solve externality problems. It makes them worse. For example, the government's increasing regulatory requirements for ethanol in fuel (of which this is an example) cause food to be more expensive and have caused food shortages (because corn is grown to make ethanol instead of for food). Yes, air pollution is a concern, but people who are starving for lack of food don't live long enough for air pollution to be a health concern for them. And nobody asked them whether they were OK with the government making that tradeoff.
The vast majority of regulations don't work. At least not if your definition of "work" is to actually solve market externalities. But they're great for job security for regulators and politicians.
> The market can never solve market externalities, by definition.
This is not correct. Markets can solve externalities, through market transactions that shift ownership so that the externalities are internalized. The main thing preventing this is government regulation that raises transaction costs so that the necessary adjustments cannot be made. This has been known at least since Ronald Coase published his famous theorem.
In other words, government regulators prevent markets from solving externalities, and then complain that markets can't solve externalities so government regulators have to step in.
It's true that there are cases where there are no market transactions that can internalize an externality. But in those cases, regulation can't solve them either; there are no solutions for such cases. Welcome to the real world.
An industry that fails to regulate itself is regulated by the government. We've had more than a decade to transition and literally zero progress. Everyone knew this day was coming since congress mandated the transition back in 2009. Crying about it doesn't solve anything — it's well past time to rip off the bandaid.
Anyone commercial already has to go in for 100hr inspections all the damn time. The STC is unlikely to cost much relative to that, nor to add much additional hassle.
Anyone private can deal with it, they own their own plane and knew it wasn’t going to be a cheap hobby going in.
G100UL will cost a bit more than 100LL but it seems likely this will change a bit as it becomes more widely used.
I guess it puts people operating midcentury radials that haven’t yet been certified for G100UL in a weird spot.
>Will I have to modify my engine or aircraft to use G100UL avgas?
>Other than placards, no modifications are required. A small placard is attached to the engine and "stick-on" placards are applied to refueling ports. In addition, there is a short POH supplement added to the AFMS.
Beautiful. The main sticking point was the (possible) need to re-certify existing planes. This is peanuts in comparison; probably why it took so long for such a fuel to get developed and approved.
Unlike lead, we've only recently had the technology to measure and quantify tire wear pollution. For example, we didn't realize until 2020 that 6PPD - already toxic to many aquatic organisms - can oxidize become 6PPD-quinone, which is acutely toxic to coho salmon and some other fish species. This solved a 20 year old mystery of so many coho salmon died after a rain storm.
That's in addition to the particulate pollution from tire wear. ("Research from Emissions Analytics shows that particulate mass emissions from tire wear is thousands of times greater than those from tailpipes, which have been vastly reduced in recent years by high-efficiency exhaust filters." - https://edition.cnn.com/2022/08/16/world/tyre-collective-mic... ).
We of course need to regulate them better because electric cars are heavier, so tire particulate pollution is expected to increase over the next few years.
There's also brake pad pollution, like the EPA's Copper-Free Brake Initiative to remove copper, "mercury, lead, cadmium, asbestiform fibers, and chromium-six salts in motor vehicle brake pads." https://www.epa.gov/npdes/copper-free-brake-initiative . That's a voluntary program, but California and Washington have mandatory requirements.
I trust that you support these efforts to reduce car pollution, and are not simply using the lack of discussion about them in this thread in order to score internet points for implied hypocrisy?
Both tires and brakes have the advantage that they are replaced every few years/decade, so regulations can target manufacturers. An aircraft engine can have decades of life, so any costs of switching away from leaded fuel are felt directly by the owner.
They’ve also been known as a class as a problem (along with catalytic converter particles) for well over 30 years.
There have been multiple studies linking proximity to freeways with asthma and decreased life span, serious health issues like COPD, and even significant increases in sudden unexplained deaths.
45 million Americans live within the high risk zones (300 feet or meters, I forget), countless new daycares, old folks homes, and residential high rises get built there every day, and almost every American is exposed significantly due to being in vehicles on average of an hour a day with insufficient filtering.
The issue here isn’t that aircraft engines last ‘decades’.
It’s that aircraft owners are only legally allowed to use fuels approved by the FAA for their aircraft, and per the various authorizations for their aircraft. Which vary. The engines may get rebuilt, but without a very expensive type change and approval (often from the manufacturer) they’re the same design as the original. Which has the same limitations.
So until there is a viable authorized replacement (per the FAA), literally they can’t use it except in emergencies. Which only just became available. And they can’t change engines either. And they can’t just YOLO it legally.
Because fuel is a major cause of crashes that kill people already (usually contamination, or wrong fuel causing engine failures/flameouts).
And despite the FAA knowing of the risks of lead (or more precisely, knowing the various factors), they only recently did authorize a replacement.
So it’s as if that study on those plastics happened 30 years ago, and we’re just now getting around to it. Which essentially is what has happened with cars and the various pollution.
So raking anyone over the coals when a far larger, more damaging, and widespread crisis has always been going on for even longer and gets ignored? Yeah I’m pointing out the hypocrisy.
It’s always about resources in proportion to risk, and arguably the FAA has dumped far more resources and mitigated a far less damaging risk (in many concrete ways) far faster with this leaded fuel issue than one near and dear all of us.
> There have been multiple studies linking proximity to freeways with asthma
Which also drives the call to reduce car use, wherein someone is also likely to point out that driving is not a right but a privilege.
> So it’s as if that study on those plastics happened 30 years ago, and we’re just now getting around to it. Which essentially is what has happened with cars and the various pollution.
Yes. And lead wasn't banned for interior paint until decades after some other countries. The US regulatory system is strongly weighted in favor of business over health and environment.
> raking anyone over the coals
As if! This is finding. The EPA must then "propose and promulgate emission standards", which the FAA must then turn into regulations.
It sets no deadlines, it makes no policy changes other than for the EPA and FAA.
I suspect it will take years before the first regulations appear, and with years to allow a changeover.
In the last 60 years the government and the FAA have killed civil aviation for anyone that isn't obscenely rich. This environmental bullshit is just one more way to keep the plebs out of the air.
Good. It's nothing but a rich boy hobby anyhow. And anyone who can afford, or even has a pilots license these days is getting paid well over 6 figures, usually as entry pay. The days of underpaid, entry level pilots are a thing of the past. This isn't the 1990s. Grow up.
Mostly because the use of lead in fuels is something to avoid at all costs. I know a lot of GA people were VERY happy to hear that they approved G100UL. Leaded fuels aren't just toxic, but they also cause issues with airplanes such as lead fouling.
>> Didn't they just legalize unleaded avgas very recently?
More specifically, I believe they certified that a particular fuel as suitable for use in ALL engines that previously relied on leaded fuel. Until that happened there was a somewhat legit concern about banning leaded fuel. What people are afraid of now is a monopoly on the new fuel leading to higher prices. But there's already a near monopoly on leaded avgas.
It would be really cool if someone developed a new aircraft engine suitable for replacing all the old models and able to run on a wide range of fuels (this may actually exist). But even then its a slog to get that engine certified for all the planes you'd want to use it on.
> What people are afraid of now is a monopoly on the new fuel leading to higher prices
If you can afford private aviation, the price of the fuel is not going to be a big concern. It's already $7-10/gallon and that is a pretty small component in the all-in hourly costs of operating an aircraft.
> It would be really cool if someone developed a new aircraft engine suitable for replacing all the old models and able to run on a wide range of fuels
As a recent article here talked about, nobody is making new aircraft for general aviation. Or at least, nobody is making anything innovative for it.
But there exist plenty of engines that are good enough for planes and can run on a wide range of fuels. They are just not getting into GA planes.
There is some interesting stuff happening in battery-electric aircraft as trainiers. You can only fly them about 45 minutes and within a local radius of the airport but they are good for people learning the stick-and-rudder basics of flying.
Gliders are even better for learning flight basics, do a better job of teaching you to anticipate and work with turbulence, and have a variable time limit.
Glider hours aren't going to count towards any useful type certification though? Unless you think someone is going to be qualified on a Twin Otter because of 1000 glider hours?
The problem is that they won't approve engines for general aviation that use unleaded gas. All the engines used in general aviation are basically 60 year old designs. General aviation is not a major concern for the FAA. It's an afterthought. And so they don't devote any time to approving new, modern engines and make it as difficult as possible.
Many, or even most, of the engines are indeed old designs. But e.g. Rotax offers certified version of some of its 900 series engines, which are a relatively new design, some with fuel injection, FADEC, etc.
The FAA legalized unleaded avgas recently, yes. The EPA (the agency this article is about) was waiting for a legal alternative before banning leaded avgas. Since the EPA can't authorize a fuel for use in aviation (that's the FAA's jurisdiction) they had no choice but to wait on the FAA approval. Since the EPA can now ban the leaded fuel.
Availability of the new unleaded fuel is extremely limited. It is also very expensive. I also believe there may be a fee involved per airplane to use it (one time for an STC). The fee I heard is nominal $250.
I have never flown to an airport with it yet. i have probably landed in over a dozen different airports in the last few months with a leaded gas engined plane.
You still have to purchase the STC for your airplane serial number and engine(s) serial number. What the FAA did was approve that all-model STC as being valid/legal to sell and "install" (which is just placards).
The problem is, "legalizing" it is like 0.1% of the work. The hard part is all the testing/certification you have to do for every single aircraft and engine design.
> The FAA signed on September 1 supplemental type certificates that allow General Aviation Modifications Inc.’s 100-octane unleaded fuel (G100UL) to be used in every general aviation spark-ignition engine and every airframe powered by those engines.
All piston engines and aircraft are certified for G100UL.
It’s actually very easy if you are the government; you just say from 5 years from now, using lead fuel is banned. And then someone else has to do the work.
Dick move to ban am additive that we've known for over a century has terrible toxic affects on people and the environment from a machine that would release it into the air? Maybe there isn't an alternative, but maybe it doesn't matter?
The amount of lead taken up from leaded avgas in the community is so close to zero
(compared to other sources) that it hasn't outweighed the damage done by essentially banning general aviation. Which is what banning leaded avgas would do without an alternative.
It's already nearly choked to death by regulation, but that was a step too far.
But they also clearly have been working to mitigate it, and now that they have an alternate are banning leaded avgas and launching it.
"General aviation" is the standard name for the part of aviation that is neither commercial, law-enforcement nor military.
If general aviation were to be banned, then as commercial pilots die off or retire, it would be difficult to hire new commercial pilots with as much experience as new commercial pilots have historically had.
This NIH study shows it as ‘small, but significant’ - accounting for anywhere from 2.1-4.4% of the lead found in children’s blood near piston airports.
Less than 5% of the amount of lead total in their blood from that source, literally for the highest risk segment you can find. Even if completely eliminated, the other 95% isn’t going anywhere.
Even if you don’t average it out across the population, it’s hard to argue that isn’t so close to zero that nearly any significant benefit anywhere else would make it not a rush.
Most airborne lead pollution now is industrial anyway, and that is clearly the calculus there. As is the #1 and #2 sources of lead ingestion for children, old paint and old pipes.
I’m glad they’re getting rid of it, but I’m not going to complain they didn’t drop everything to rush it. Especially since if they did, they’d almost certainly kill more people in the resulting plane crashes.
Glad to hear, it should have been phased out a long time ago. Assuming there aren't any issues with the only very recently legalized unleaded avgas I don't think there are any downsides.
TEL is incredibly bad stuff*, but it's rarely used in commercial flight operations as they predominantly use jet aircraft. Leaded avgas is completely unnecessary as non-TEL fuel formulations have been created and certified. The problem is they're not available anywhere, while leaded avgas is everywhere in GA. Municipalities should do like they did for leaded automotive gasoline: supersede commercial interests with public health regulatory ones and ban it. (The EPA only banned leaded automotive gasoline nationwide in 1996 after allowing 25 years for the phaseout.)
* In the same category of human harm as nerve agents, dioxin, and methylmercury.
The first general purpose non-TEL alternative was only certified last year. Before that, each variant had to be certified per-type, and then would need to be stocked everywhere. Which never was going to happen, and didn't.
Now they're going to ban leaded avgas, which should force the for adoption, since there IS now an approved general purpose alternative.
It’ll probably take another 10-20 years to outright ban it. Though the EPA might make it illegal to manufacture any engines that use leaded gas far sooner than that.
Now that there is an unleaded alternative, older planes will slowly replace their engines at the next engine rebuild. There is a grave pilot shortage already and the FAA loathes to make GA even more inaccessible than it already is so it’ll be a slow process.
>Will I have to modify my engine or aircraft to use G100UL avgas?
>Other than placards, no modifications are required. A small placard is attached to the engine and "stick-on" placards are applied to refueling ports. In addition, there is a short POH supplement added to the AFMS.
The engine change is shit pushed by the leaded-gas manufacturing lobby.
> There is a grave pilot shortage already and the FAA loathes to make GA even more inaccessible than it already is
Lol, inaccessible? Y'all don't even need airstrips to take on and off, for Part 103 ultralights technically not even a license. Meanwhile, here in Germany, first pay up thousands of euros for the ultralight cert, and you have to use dedicated airstrips instead of your farm's field. Oh and if you want to get beyond ultralight, do everything from scratch for the PPL, no credit/transfers.
There's also distribution problems. Jet fuel aside, most airports only have one tank for servicing avgas. Once they switch over to non-leaded, now they have a customer base that may not be able to buy from them. Those revenues go to fund the airport operation.
There's going to have to be a concerted effort to fix type certificates and fuel distribution all at the same time. A slow effort is going to be more problematic.
Not so fast. G100UL can be approved for all piston engine aircraft. There is not a blanket approval.
You still have to go here (https://stc.g100ul.com/aircraft/) and buy paperwork that makes your individual airframe and engine legal. What the FAA approved was for GAMI to sell that paperwork for all piston aircraft.
I wonder what the Venn diagram of single-engine plane owners and people who don't like being told what to do looks like.
[I am seriously curious; on the one hand, owning and flying a small plane is an expensive, privileged hobby which tends towards the lower-upper-class demographic, but it also requires complying with a shit-ton of government regulation and direction already.]
I'm in the car hobby and considering how many people just think stuff like noise regulation and air quality measures is just nonsense solely on the basis of "I do what I want, bitch", I'm not hopeful.
That doesn't seem to be the norm here and we're pretty lax on emissions testing requirements. It was a bigger issue in California when I was in the car scene there than anywhere else i've lived. And their emissions are stricter than most places (if not all) in the US.
> older planes will slowly replace their engines at the next engine rebuild
An alternative exists, but the FAA needs to certify it for each aircraft type. The majority of aircraft types are not certified for this. No A&P is going to do this because the plane won't be legal to fly in most cases.
And at the risk of editorializing, I've never seen the FAA do anything with the goal to making GA more accessible, at least not intentionally.
>> An alternative exists, but the FAA needs to certify it for each aircraft type.
They have. It's done. nobody needs to worry about liability for switching. Availability will be a short-term problem, and banning leaded fuel will get it fixed quickly.
Cruise just needs to move to flying airplanes. With all the anti-GA and anti-airport astroturfers there will be no one to fly them for their vacations.
People just can't see the end result of their ideologies.
I've got about 50 or 60 pilots from India and Venezuela doing circles around my local airport who would like to differ. What about using G100UL makes it inaccessible? Worst case scenario, if $1 per gallon makes that much of a difference, you can just drive your car less and ride your bike around the neighborhood to offset the cost of fuel.
Why are diesels so uncommon among piston aircraft, it's almost always avgas? Is it just "because that's how it's always been" or are there actual engineering reasons diesel are inferior? Cursory searching suggests it's mostly this inertia.
It'd be especially useful if they could run on regular jet fuel, then turboprops/jets and pistons could use the same fuel infra.
Diesel engines operate at higher pressures and must be considerably heavier to achieve the same performance & efficiency. Not a huge issue for ships, trains, or cars. Huge issue for flying stuff.
As the sibling comments have pointed out, power-to-weight is the main reason, but it doesn't make diesel engines completely unfeasible for light aircraft.
Diamond Aircraft have had success selling planes with diesel engines recently, and even started a subsidiary company to manufacture them: https://en.wikipedia.org/wiki/Austro_Engine
As others mentioned, diesels tend to have worse performance/weight due to heavier construction.
In the early days of aviation (like 1930's or such) there was some effort to introduce diesels for long-range aircraft, the idea being that the heavier powerplant would be offset by the lower required fuel load due to better fuel economy. But they weren't successful.
More recently there has been something of a renewed interest in aviation diesel engines, the motivation being they can run on Jet A-1 in addition to diesel fuel. Jet A-1 is what jet (and turboprop) aircraft use, and is available at basically every airport worldwide, is much cheaper than avgas, and no risk of being phased out like the leaded avgas being discussed in this article.
So I know absolutely nothing about chemistry, so can someone explain to me why lead was added to gasoline in the first place? Disregarding its toxicity, what benefit does lead buy you?
> It is a fuel additive, first being mixed with gasoline beginning in the 1920s as a patented octane rating booster that allowed engine compression to be raised substantially. This in turn increased vehicle performance and fuel economy.
If you want a fascinating story telling video with a lot of sciency stuff for the relative layman, here's an excellent one by Veritasium on how it happened.
"The Man Who Accidentally Killed The Most People In History"
https://en.m.wikipedia.org/wiki/Thomas_Midgley_Jr. He was a fascinating man, relatively non-famous. Probably singlehandedly contributed to more environmental damage than you can imagine. Died in a strange way too.
My understanding (and I'm no authority in this subject) is that adding lead to gasoline allows achieving better octane ratings (ie lower chance of self-ignition). This reduces engine knock, which makes the engine live longer, also allows pushing more fuel into a cylinder per ignition cycle more confidently.
These things are possible without lead as well, it just costs more money to do so.
It's about increasing the compression ratio without self-ignition. High compression ratios mean higher power for the same weight, and airplanes are all about minimizing weight. You also get higher efficiency. Again, lower fuel weight = good.
You can dump as much fuel in the cylinder as you want (in fact, most airplane operating handbooks call for a very rich mixture on takeoff because of the cooling effect).
Half the story is the lead acts as a octane booster, but raising the octane without lead chemicals is trivial. MTBE works, so does just selling pure toluene. The issue is that in addition to raising the octane, some metal lead deposits around the valves which maybe makes them seal better and switching away from lead could cause engine failures unrelated to octane.
It allows the fuel to withstand higher pressures without detonating in an uncontrolled manner. This is important in aircraft engines, which run at a significant fraction of their maximum power output for most of their working lives.
People have been looking for alternatives for a long time, but it's difficult because leaded aviation gasoline is not a very large market, and there are substantial regulatory obstacles.
So higher octane means it needs higher temp/ pressure to burn? I've completely misunderstood octane my whole life.. i always thought it meant "high octane make engine brrrrrr fast"
Higher octane allows it to get compressed more before it goes boom, which means you can make a more powerful engine.
But adding high-octane gas to a normal engine doesn't make it go any more boom, in fact, it goes less boom because it doesn't burn as much when it booms.
Modern engines can be designed to advance or retard timing based on knock, so they can run on different octanes and provide different power curves.
>But adding high-octane gas to a normal engine doesn't make it go any more boom, in fact, it goes less boom because it doesn't burn as much when it booms.
It’s probably not your fault. It always annoyed me when old (20-30 years ago) Shell gas commercials would imply that high-octane (read: much higher profit margin) gasoline would cause your engine to make more power. Now, they didn’t actually say that outright, because it’s not true.[0] But if you put Shell gasoline in your car, you were told that you’d “feel the power your car is capable of”, or some weasely bullshit. The word “power” was used a lot in that commercial, just never next to the word “more”.
I was a professional mechanic around that time, and I had coworkers that thought that not only would high-octane gas give more power, would also swear it increased fuel mileage. Neither is true. High-octane fuel has less energy per gallon than lower octane fuel, it can’t give better mileage. (Now, “mechanic” != “engineer”, but c’mon, guys.)
[0] Yes, Captain Pedantic, I’m aware of knock sensors and computerized ignition timing. It was a quarter century ago.
> I’m aware of knock sensors and computerized ignition timing. It was a quarter century ago.
This stuff started to show up in the late 1970's-- the 1981 280ZX Turbo my dad had was equipped with a knock sensor and would retard timing and add fuel.
And just to highlight and explicitly explained the weird edge case that GP mentioned...
On many modern cars, high octane gas gives you more boom. They are designed for high octane gas, but the engine management computer is able to detect low octane gas and prevent damage from predetonation-- giving up some power.
This is probably not true of modern naturally aspirated cars. Maybe they could lean out the mixture a little to get a bit more efficiency on higher octane, but they largely can't leverage the higher octane fuel as well as a car with an electronically controlled turbocharger system.
>They are designed for high octane gas
The vast majority of modern engines are designed for 87 octane, and not downrated to 87 octane, because that would give you poorer performance than a clean sheet 87 octane design, and single digit percentages matter here.
> This is probably not true of modern naturally aspirated cars.
There's a whole lot of cars that say "Use premium fuel only" with compression ratios of >10.5:1, but rely upon anti-knock sensors to retard timing (and adjust mixture) to avoid detonation with 87 octane fuel.
Great comments on the subject here - pardon the gross over simplifications please. I'll add what I know. "Octane" can be thought of as "Resistance To Pre-ignition" where the higher the octane number, the more resistant the fuel mixture is to ignition/burning. Lower octane fuel can have a tendency to pre-ignite via cylinder compression (compression on the upstroke raises cylinder temperatures to the point of combustion) rather than ignite when the spark plug fires. This is whats called "knocking" as in the benign case it cause the engine to make a knocky-rattling sound ( not unlike a diesel which in fact relies on compression ignition as a feature of its design ). In the bad case, pre-ignition can cause catastrophic engine damage where engines "grenade" themselves.
More or less, if you want to build a light weight/high power engine you want a higher compression ratio. As the piston travels upward on the compression stroke higher pressures are achieved and this allows designers to take advantage of different crank/cylinder characteristics to make more power in a smaller, lighter package.
We used lead in car gas because engine timing technology and fuel delivery technology were analog/mechanical and really very limited in terms of tuning potential. The cheap hack was just to use a fuel that was more resistant to burning in the first place. Just add a hotter spark/ignition system and it was good to go design wise. Given the old tech running in most GA planes, this was a natural thing to do at the time and the problem was well understood. To point here, modern non-lead additives have been around for a long time and the problem can be adequately solved with a non-lead substitute.
If you wanna get deep with this, take your old normally aspirated car and bolt a turbo on it!
Waiting for the Tesla of the aviation as that lead vs. unleaded feel like something ancient.
Lets look at numbers as of today:
Cesna 172 - 75kw engine, on 50kw power makes 1000km as 200km/hr. Engine plus fuel weight 350kg. The engine costs $26K.
Today's lithium batteries like ones used by Tesla is 280wh/kg. At retail similar batteries cost $400/kwh.
So, we can have 75kw electric engine and 100kwh battery at the same weight as ICE engine plus fuel on Cesna 172 and at a retail cost of $50K and have 2 hr flight of 400km. That isn't a worse starting point than what Tesla had 15 years ago against ICE cars.
Any aircraft mechanics care to comment on this? I know lots of small privately owned aircraft are really really old. Like 50s or 60s or older. Is this going to screw up their fuel system gaskets and seals?
I suspect what needs to happen is that someone (ASTM?) comes up with a spec for unleaded 100 octane avgas, and then the FAA can give a blanket approval for that spec for any plane certified for 100LL.
Can't (realistically) be done. The specification for most airplane engines say "100LL" and the specification for 100LL is a composition specification (ASTM D 910), not a performance specification.
If your fuel meets ASTM D 910, it contains lead. If it doesn't contain lead, it doesn't meet ASTM D 910 and therefore definitionally isn't 100LL, so if your engine type certificate data sheet calls for 100LL, it unavoidably calls for lead.
If you are flying an aircraft that is thus-certified, flying it with a different fuel is, per the FAA definition in 14CFR3.5, flying an unairworthy airplane.
"Airworthy means the aircraft conforms to its type design and is in a condition for safe operation."
That's the legal reasoning that the Gami STC is required: to change the TCDS of the engine and airframe to permit a fuel other than 100LL and still be considered airworthy. (The STC process is totally workable and, IMO, doesn't need to be "fixed" and Gami has basically done the work you're asking to be done AFAICT.)
Weren't many of the planes in operation today certified before 100LL became the only available grade (excluding things like 115/145 or even more exotic brews which I guess today are used only at Reno air races and such)? E.g. 80/87 for lower performance engines, and 100/130 for higher performance ones. So presumably they were somehow grandfathered in when 100LL replaced these grades? So why can't the same be done for a hypothetical "100UL" spec?
Based on the type certificates for the common airplanes and engines I looked at, the type certificates were re-issued with 100LL as an/the approved fuel under the type design. (This would be done after testing as required by FAA.)
That’s what the STC process does legally, just being done by the engine/airframe manufacturer instead of third party (presumably because they wanted to continue selling engines/airframes).
Maybe. Most automotive engines ran just fine for a normal lifespan without changing the valve seats. When you work the engine hard you need it, but if you are not racing you generally got by with it. Of course the change for automotive was the early 1980s when engines were not as reliable and didn't last as long.
Don't forget that aviation engines are require a lot of regular rebuilds. In a car you wait until something breaks, in an airplane you replace parts long before they might fail to ensure it doesn't break when in the air. So for many we can just add replace the seats/valves in the next tear down and be okay.
Gee if only the FAA could have certified unleaded gas some time in the last 3 decades. It’s not like us GA enthusiasts enjoy depending on an expensive leaded gas.
"Do no harm at all costs" regulatory bodies need to be overhauled. E.g. NRC, FAA
IMHO, it'd be much better to have an explicitly adversarial and separately-funded dual-track system at such agencies, similar to how the justice system works.
E.g. FAA-Innovation (responsible only for their goal) makes their strongest case and presents research on why unleaded gas should be adopted ASAP. FAA-Safety (responsible only for their goal) makes their strongest case on why no change should be made.
All arguments and facts are published in public. Then higher-level decision makers arbitrate and make a call.
The root of all evil is that from a career perspective, "defer and take no action" is always safer for individuals in positions of regulatory authority. Worst case, something that's always been wrong explodes, and you blame it on the last person.
In the current blended safety+innovation system, it's too easy to obfuscate intentional inaction in endless "more study is needed" bullshit.
The "separately-funded dual-track" is already there - It's the EPA, or congress. The FAA's mandate is to ensure safe flight. it shouldn't be up to them to be setting environmental rules. Environmental rules should be set for them, and they should figure out how their industry can meet those rules.
The exemption for leaded fuel in GA should have expired a long time ago. It's ridiculous that the FAA was allowed to keep punting this issue essentially forever, and the only reason a transition is happening now is because they finally decided to take responsibility for it, rather than because there was any legal requirement for it.
The FAA would have been totally happen, probably ecstatic, to allow an external mandate from someone like the EPA end leaded avgas while they had no replacement, effectively killing general aviation. They could have pointed fingers at the EPA who would have pointed back at the FAA, meanwhile GA would be dead.
yeah, that's always the threat - "following basic environmental safety rules will kill ____". but just because you say it, doesn't make it true.
GA flying is important for a lot of industry, and a lot of remote communities. it might have taken some work, but they could have found a way to use unleaded fuel in airplanes in fewer than 50 years.
I've often thought about an evolutionary model of organizations, in which a challenge is presented, an A/B test is created, an the winning process would win out over the loser, making the organization more effective over time.
Having written this, it almost seems like too obvious of an idea to even post about...
I worked at HubSpot for a year before their IPO and a year after. They used this approach of basically spinning up multiple different teams in different orgs to solve more or less the same problem.
For example, before they figured out how to sell and onboard SMBs, there was at least three teams working on solving that problem while I was there, including mine.
Once there was a “winner”, that team would get more funding (aka budget) and the people on the other teams tended to be absorbed into the winning team or would be repurposed onto other projects.
This wasn’t a codified, explicit operating system, but basically is how they worked for awhile (but I’m unsure how it works now.) The gist was to hire smart people and let them figure it out.
Approved but not available. Believe me, everyone wishes we could just move on from leaded avgas, but it seems like the FAA wants to drag this out as long as possible.
Lack of options should never have prevented lead being outlawed. Ask anyone on the street "Would you like to drink this potion making you dumber so that someone else can fly a plane up there" and everyone will say no.
Clearly it isn't okay to harm someone without their knowledge or consent.
Where exactly do you think your airline pilots come from? You know, the ones there is a giant shortage of right now… Do you think they grow on trees? They learn to fly in those small piston planes.
as a diesel engine mechanic ive always figured there was some amazing conspiracy about leaded avgas. Here on the ground, diesel regulations and formulations are basically a yearly theatricality. new scrubbers, new regenerators, fuels you can use and fuels you can never use, and special locations and applications for the fuels if you use them at all. The regulations are pretty rigorously developed and enforced.
I remember conversations about using unleaded gas in aviation 40 years ago. And the pro side's argument is auto grade gasoline is highly regulated with better quality control and standards than leaded aviation gas. And pointed out that cars run just fine at the altitudes light aircraft fly at. SO I hear you on that. It's a bit inane.
If there is a conspiracy I suspect it's the government exerts a light hand on things rich people do.
What surprises me is the refineries didn't tell the light aviation industry they weren't going to make leaded gas anymore. If they'd done that the Feds would have kicked them some cash to develop an unleaded version.
Apart from specialty applications, auto engines run at a small fraction of their full power output the overwhelming majority of the time.
Aero engines run at a substantial fraction of their rated power output basically full time[0].
The fact that auto engines can be run on unleaded, lower octane gas at 10,000' or more doesn't really tell us that the same low octane unleaded gas is suitable for an aero application.
> What surprises me is the refineries didn't tell the light aviation industry they weren't going to make leaded gas anymore.
You can just add lead to unleaded gas (which was legal until 1996 in the US), so even if you could convince them to be altruistic in this way others could just work around it.
Its not so much a conspiracy as just not as big of an issue compared to diesel consumption
About 11 thousand barrels of 100ll are produced every day in the US. Compare that to 4.9 million barrels of diesel daily, and you can see why it is a bigger priority. In this case 100ll is a literal drop in the bucket.
But also its a rich guy hobby that generally isn't very visible.
If your standard diesel engine fails it’s generally not a life threatening emergency though so change is much safer. Aviation has safety and regulatory habits written in blood.
These are multi redundant and generally hospital patient monitoring systems have additional batteries of their own to make sure people don't die, and in the case of a major clusterfuck there are emergency procedures in which it's specified how power will be restored assuming a grid and backup generator failure (usually it involves the fire department shuttling a generator pack to the hospital site).
With engine failures in aircraft however, the consequences can be way more dire - particularly in GA where it's (at least in the US) even being allowed to fly without a license at all (Part 103 ultralights), and forget about regular legit simulator training on what to do in that case.
It's very easy to run emergency backup generators in parallel.
Take your total load (10MW) divide by 5 (2MW) and you need 5 2MW generators, buy 7 and run 6/7 and your "down for yearly maintenance" generator can be offline while your "oh shit we installed the wrong fuel filter and the injectors clogged" generator also fails.
Especially since rarely does anyone care about how heavy the emergency generators are. But if you add 100 lbs too much in the wrong place on a GA plane, everyone is almost certainly going to die.
It sounds like this is setting the stage for the FAA to be forced to make a move...
> the FAA has a statutory mandate to prescribe standards for the composition or chemical or physical properties of an aircraft fuel or fuel additive to control or eliminate aircraft emissions which the EPA has found endanger public health or welfare under section 231(a) of the Clean Air Act. In issuing these final findings, the EPA is making such a finding for emissions of lead from engines in covered aircraft.
The saga of unleaded avgas has been long, expensive, and slightly ridiculous. It's not just FAA - not by itself, although regulatory capture is, of course, a frickin' plague. You had a big ol' mob of aerospace companies racing to lock in their engine designs for the next forever via mandated fuel specifications. This is the Golden Fleece in this industry: if you can get to write the next mandated spec, you can relax on your money bed for the rest of time.
One of my friends that helped me build hours does experimental aircraft and just runs his c172 on 91 unleaded from a highway fuel pump. Pretty sure he has a lycoming IO-360M1A on it. He does have to haul fuel in, however.
American aviation does need an overhaul. I used to fly with some guys out of a private hanger and a few nearby FBOs. Pilots would occasionally grumble about changes made to flight regulations and airport procedures during the 1980’s. Even the most staunch republican would bad mouth Regan for it.
I bought some unleaded AVGAS in 2017 at an airport in Falmouth, MA.
Power tools run much better on it because it contains no ethanol.
My portable generator starts much more easily after sitting for a few months if I use AVGAS instead of what I buy at the pump. It's because the ethanol gums up the carbonator.
Yup. Old small piston airplanes had an exemption to use leaded gas "for safety". Mind you, these are the engines running on 1950s tech that still have carburetors. The failure to test and approve an unleaded fuel lead is a long and unpleasant story.
I mean, brand new single-engine prop planes with modern fuel-injection systems are also running on leaded gas, so the fact that really old planes also are is kind of obvious/irrelevant. With a handful of exceptions, single-engine prop planes are only certified to run on 100-octane leaded gasoline. For many (maybe even most, but I don't know the exact numbers) certified aircraft there is no legal path to get it to run on any other type of fuel. Certain planes have supplemental type certificates to allow an expensive conversion but it's far from the norm.
> With a handful of exceptions, single-engine prop planes are only certified to run on 100-octane leaded gasoline.
This was true up until last year, when G100UL was approved as a drop-in replacement for 100LL. It does require a STC and the associated paperwork, but this is apparently pro forma and quite cheap, and doesn't require any modification to the aircraft apart from some placards. The problem, of course, is that G100UL isn't really available anywhere yet, while 100LL is still ubiquitous.
> "For many (maybe even most, but I don't know the exact numbers) certified aircraft there is no legal path to get it to run on any other type of fuel."
Until recently this was true. But since September 2022, G100UL is legal and certified for "every spark ignition piston engine and every airframe using a spark ignition piston engine in the FAA’s Type Certificate database.”
You're right, some GA engines use fuel injection, also a 1950s technology. I used to fly a Cardinal with Lycoming IO-360. We got the fancy GAMIjectors and it made a huge improvement. Yes, the big exciting 2000s technology was "the holes in the injector are sized to provide calibrated fuel flow".
While I'm rambling, the dual spark in a GA engine is really interesting.
Yes, I understand using leaded gas in older designs. But what was the manufacturer's excuse to keep designing engines that require leaded gas even on fuel-injected, ECU equipped newer designs?
Not a rhetorical question, I am genuinely curious.
New and old designs have been tested and can work with unleaded fuel. (Edit: there are surely some exceptions here, so I don’t mean this to be all encompassing)
New designs must work with leaded fuel since that is the fuel which is available - until avgas contains no lead this will continue to be the case.
Side note, most new planes are sold without an ecu.
Sure there are, but the 100 in 100 octane avgas refers to MON, not RON. 100 MON fuel is a bit trickier to be done without lead, although we now have G100UL which does it.
"older ICE powered prop planes" in this context means any prop plane, and about 95% of those used for GA. Brand new ones require leaded gasoline as well because with the exception of fuel injection the engine designs are basically identical to those 50s and 60s era planes.
Being more pedantic, turboprops use gas turbine engines to power the propeller. "Jet engine" is incorrect when referring to gas turbine engine other than turbojets, such as turboprops, turbofans and turboshafts. Turbojets were the first variant of gas turbine engine to be put into use so "jet engine" ended up being used as a common term. Modern "jet planes" often use turbofans for their greater efficiency at similar performance levels, but "fan plane" sounds silly. The M1 Abrams uses a turboshaft engine but I've never heard it called a "jet tank" (which sounds badass).
They don't require leaded gasoline, they require 100-octane gasoline. It's just that until recently, a certified, unleaded 100-octane avgas did not exist.
IIUC, it's both, but you're right lubrication is not it's primary purpose, but I think the reason leaded fuel is hard to replace is that the lubricating properties are difficult to replicate.
> wherein it served as an effective antiknock agent and reduced exhaust valve and valve seat wear.
Until very recently, you legally weren't allowed to fly most GA aircraft on anything other than 100LL. Thank the FAA for dragging their feet on certifying a replacement.
Not much thankfully. It's only small General Aviation piston aircraft and there aren't many of them relatively speaking. It's not like in the 60s when there were thousands of car engines per city constantly pumping it out. More like 10-20.
This is why the FAA wasn't in a huge hurry but at the same time they were WAY too slow. It should have been a crash priority honestly.
It's likely that every kilogram of lead you atomize into the air has a far worse impact on people and the environment than a kilo of lead in, for example, electronics, paint, or flashing.
Increased lead in crops grown within a few miles of airports has been noticed.[1].
As had reduced IQ's in children living near airports. [2]
Yeah, they should have ended 100LL a long long time ago. It's crazy how such a small amount can cause so many problems. Imagine what it was like back in the 60s. Utter insanity and they KNEW that it would cause problems.
Unfortunately there is growing evidence that lead stays in soils for decades or maybe centuries. I can imagine in the future that lead contamination of farmland might mean that we end up with a kinda crazy reversal - we end up growing all our food in undeveloped places like south america that never had as much lead contamination, and food from the USA and other developed countries is so lead contaminated that it gets exported to places like africa where they don't have strict regulations against contaminated food.
Undeveloped countries stopped using lead way after the USA. Lead contamination was a huge issue in Africa and the Middle East. It wasn't until 2014 that lead use in auto fuel was ended worldwide.
Luckily lead is very heavy and chemically active which makes it much easier to remove from soils than some of the nastier contaminants. You can essentially break it down with sulphur amendments to acidify the soil and then let the plants do the rest of the work. Eventually dilution does the rest of the work until it reaches background levels.
No, but our understanding of 'acceptable' lead levels keeps getting lower. One day, the amount of lead in our crops which we might today consider acceptable, in the future we might not.
Imagine if 100 years from now, Brazil is an up and coming economic powerhouse, and economists figure out that they are doing so well because their strategists, businesspeople, scientists and engineers are all smarter because their food contains less lead than ours does. We'd quickly start outlawing high lead food, which in turn might make big swathes of our cropland unusable for food.
Yes and there's some areas near popular flight schools with significantly elevated lead levels because there are constantly planes flying overhead using leaded Avgas. It was a special carveout because recertifying every engine that was designed to use leaded gas is a pretty big lift and has significantly higher safety implications when the engine is in a plane instead of a car. It is only for some types of engines but those are more common on the older more affordable planes.
> recertifying every engine that was designed to use leaded gas is a pretty big lift ... instead of a car
Wrong on all accounts. There are orders of magnitude less engine models used in air than cars. Profit margin for airplane companies are higher than cars (though volume is much lower). cars use the same model worldwide and pass certification all at once, planes sell in one country and customers are mostly responsible for 'acclimatization' or whatever they call it in your parts, but it usually is about lights color and placements or some nonsense.
the one thing that made planes be so slow, is that people who own planes have much more voice over legislation than people who own cars. Nothing else. That's why the whole industry used tax payer money to certify one special new gas type that will work on all existing engines (again, possible because much less variety, making it easier technically). You breathed lead for 60 years of legal lethargy just so a few people didn't have to spend a few pennies on their plane maintenance.
If a car engine fails or is suffering more long term damage due to knocking the car doesn't have an immediate emergency on the same order of magnitude a plane does. A failed plane engine is an immediate life threatening emergency to everyone on board.
While there are fewer models, the amount of paperwork per model is orders of magnitude higher. And many of the manufacturers for the most common models no longer exist in the form they were when the engines and planes were originally designed and certified.
Oh, and unlike with a car or truck, engine failure in a light plane, especially during takeoff, is VERY likely to result in death or serious injury.
Pretty low. Even in the highest risk populations (children in very close proximity to piston aircraft airports), less than 5% of the body lead burden can be attributed to that source. I linked to the NIH study elsewhere in here.
It's notable, and is being banned for it. But when it's gone, it won't make any significant difference.
Look, nobody is defending the FAA on this. GA pilots have wanted this for decades.
There was a carve out because plane engines are expensive and old (the most common engine today is a 50 year old model). Presumably it was expected that carve out would just be temporary while we worked on finding an off ramp to unleaded avgas. Nobody wanted the FAA to just ignore the problem for decades.
For the public it's a relatively minor issue except where you have both high levels of traffic and low level flights of the kinds of planes that use leaded av gas. Without that combination the effect on real gas levels are minor. Ideally we have no lead emissions of course but the effects are tiny if you don't have those two factors.
Double or triple that of a car, for a small plane, because of the higher fuel consumption.
But this only affects avgas, which is high-octane gasoline for propeller-driven aircraft. Jet-A1, which is light diesel fuel or kerosene-like for jets doesn't contain lead.
Can anyone get this page to work? I typed in about a dozen different airports I've flown into and not a single one shows up, but if I type random characters I can get some airports to show.
This could be an incredibly useful tool if it worked (and wasn't limited to just a few years worth of data).
Don't know about the US, but we had leaded petrol (gas) for cars much later here in the UK, ~2000 at least. I remember my mum's Austin Metro (which was from the early 90s/late 80s) ran on it, and we only replaced that car once I was in high school (and that was in 2001)
No, commercial airplanes all use unleaded jet fuel. But the small, 2 and 4 seater general aviation planes you see are almost all using 60-year old engine designs that run on leaded fuel because the FAA doesn't want to devote time to approving new engines for general aviation.
Pretty sure no one's defending it, just explaining why it stuck around. It seems pretty unanimous "spraying lead everywhere is bad so leaded fuel is bad."
Nobody as far as I can tell is defending leaded fuel. Just explaining why there was initially a carve out. Having that carve out made sense at the time. Having it last until 2023 is malpractice.
Since according to another post in this thread, 11000 barrels of leaded are produced each day, vs 4.9 million barrels of diesel fuel seem to be the numbers, not a huge amount. However it is still good that the law now allows unleaded.
Safety regulations are written in blood. There should be a long and careful process before any so-called improvements from modern technology are forced upon us. In making new kinds of gasoline, chemical engineers should really consider safety and ethics. And every one of them should first be required to study the humanities.
Stop making guinea pigs out of normal people. Gasoline is a volatile substance. Just changing it willy-nilly without extensive testing is unethical. There's a reason the FAA hasn't certified it. Safety regulations are written in blood.
I’ve never met a group more resistant to change than GA enthusiasts. They think they have a God-given right to fly the same way they did in the 1940’s.
I was getting into it right as the ADS-B rules were coming into play. It is a cheap and easy (by aviation standards anyway) technology designed to prevent mid air collisions, and you’d have thought the FAA was requiring them to murder their children.
change has only ever been bad for GA. GA is now just a really expensive sport for old people who bought their planes 40 years ago when Beechcraft ran ads in National Geographic. Of course they are going to be resistant to change, and possibly rightfully so because GA is 1 or 2 steps away from being completely dead.
As one of those grumpy old pilots, I can understand it. Change (especially regulatory change) in GA usually translates into one of the following: 1. Making this very expensive hobby even more expensive, 2. Making this inaccessible hobby less accessible, 3. Moving more from the hobbyists to commercial interests (airliners).
There have been great exceptions (Medical reform + BasicMED, small recent changes around experimental/amateur-built category, and the upcoming MOSAIC reform), but I think the old fogies have a point about the damage change tends to bring to this activity.
This is fine though. Much as I loved when my grandpa would fly me around in his cessna, and taking flying lessons myself, there's no "right" to a GA hobby, or any hobby with huge externalities. Some things belong in the past.
No sympathy. Where I live, there are strong noise restrictions on holidays and Sundays. A huge proportion of the population support this - it is very nice to have days without lawnmowers, chainsaws or whatever.
Who is exempt? Aviation. One plane makes noise over tens of thousands of people. The absolute worst are the stunt planes.
I don't disagree with your statement, but I'll note that as it pertains to engines in the GA world, there's not a lot of options that weren't designed in the 40s.
In neighborhoods or cities that happen to sit under take-off or approach paths for, or downwind of, very-busy airports that see a lot of prop plane traffic? Maybe a measurable amount.
I'm concerned about everyone. When you start getting lead into corn and wheat, it gets into flour and bread and pasta, and before long, everyone has eaten some.
Sure - some have eaten more, and others less. But everyone has been impacted. Half of the US population has blood lead levels above the CDC 'safe' level.
> Half of the US population has blood lead levels above the CDC 'safe' level.
That's a bogus statistic. I went to look up what you could be talking about, and it appears to be pretty shoddy alarmism, not on your part but poorly or shadily written reports. (disclaimer/reassurance: Lead is bad for us, and heavy metal exposures are cumulative over a lifetime, so the lower the better, and we should keep lowering.) But what you quoted implies that we are not succeeding quickly enough, and from things I looked at, that is not a conclusion that can be drawn.
I didn't spend a lot of time on it, but just from a few headlines and an abstract, it's clear that the lead levels under consideration have been lowered recently (and for what I'm about to say, undoubtedly previously lowered other times), and are not toxicity levels but more like "hey, there's lead in this neighborhood". And the lead exposures they are talking about are "retroactively" encompassing the elderly who were exposed as children before the new levels (and unleaded gas) were a thing.
So, they're saying "Among the entire population, half of people have previously received during childhood lead exposures when we didn't have current standards that we would now consider to be, not even unsafe, but where geographically we should focus our attention looking at the sources."
2021, CDC updated the blood lead reference value (BLRV) from 5.0 μg/dL to 3.5 μg/dL. A BLRV is intended to identify children with higher levels of lead in their blood compared with levels in most children... It is not a health-based standard or a toxicity threshold... should be used as a guide to 1) help determine whether medical or environmental follow-up are recommended and 2) prioritize communities with the most need for primary prevention of exposure. .. BLRV is a population-based measurement that now indicates that 2.5% of U.S. children aged 1–5 years have BLLs at or above 3.5 μg/dL.
Considerable effort is expended to protect today's children from lead exposure, but there is little evidence on the harms past lead exposures continue to hold for yesterday's children, who are victims of what we term legacy lead exposures. We estimate that over 170 million Americans alive today were exposed to high-lead levels in early childhood, several million of whom were exposed to five-plus times the current reference level [which is not a health or toxicity level]. Our estimates allow future work to plan for the health needs of these Americans and to inform estimation of the true contributions of lead exposure to population health. We estimate population-level effects on IQ loss and find that lead is responsible for the loss of 824,097,690 IQ points as of 2015.
...and you can't add IQ points like that, most especially if you are part of the substantial segment of the population that says that IQ is a bogus measurement, a segment that heavily overlaps with environmentalism.
While the effects of lead compound over a lifetime, the measured figure is blood lead levels, which will drop to zero if you stop consuming lead, with a half life of 28 days.
Therefore, the measurements made in 2023 mostly reflect lead actually consumed by humans in 2023.
except the sentence I quoted from the report says it's talking about previous exposure in childhood. The original point I was responding to say half the population; children are less than a quarter of the population.
"...yesterday's children, who are victims of what we term legacy lead exposures. We estimate that over 170 million Americans alive today were exposed to high-lead levels in early childhood, several million of whom were exposed to five-plus times the current reference level"
Probably a negligible amount, 100LL is pretty much only used in single engine GA planes and each one produces the pollution equivalent of a few cars. There might be a measurable effect near GA airports but over the entire country? Basically no change.
If my maths is correct, general aviation emits 380 tons of lead per year into the atmosphere.
If just 0.1% of that eventually ends up in a human (remembering many plants humans eat, like potatoes, bioaccumulate lead. Also, some lead may be consumed multiple times, since biosolids are used to fertilize crops, allowing the same lead to be consumed twice), the dose is still 100x the daily max consumption for every single american.
The NIH study I linked elsewhere shows less than 5% of the lead in the highest risk populations can be attributed to leaded AVGAS. It's waaay lower for everyone else. Those are young children within 500m of a piston/GA airport. The other 95% isn't going anywhere after this.
Good to get rid of it? Yes. A serious factor in society wide human lead exposure? No.
Would you consider elaborating upon this? I don't have a reason to doubt you, but I am also picturing the people who fly airplanes as being sympathetic to older machines.
And I'm in that camp of unscientific people who figure a 23 old truck (specifically using unleaded fuel) that doesn't need to be rebuilt anew is actually kinder to the earth than the alternative.
I remember the legal precedent set during the trial of US President Bill Clinton. He claimed the law he was being sued under (sexual harassment) was unconstitutional, which it was. The problem was that he signed it into law, and not even The President can not be that big of a hypocrite in an American court room. So he lost. If someone is blatantly hypocritical, I have a great desire to hoist them with their own petard (to use their argument against them.)
Since the people who fly the largest private planes openly demand I stop driving my old pickup, I make the much more moderate demand that their airplanes meet each and every single emissions and fuel economy requirement that my old pickup has had to meet to stay on the road all these years.
I 100% support grounding all civilian air travel, world wide. I would give them the same time I would have if my old pickup failed an inspection to come up to standards, or their planes would be scrapped. Good luck to them getting catalytic converters on jet engines.
> I wish to point out that those who fly private airplanes (including those using leaded avgas) are the most likely to demand I stop driving my 23 year old pickup.
Citation needed. Did you actually experience this, or is this a hypothetical?
I do not know why pilots would be giving you a hard time with a truck given that most general aviation aircraft in operation are older than your truck.
What I have seen is people driving brand new trucks calling all GA aircraft a 'rich person's toy' even when they cost much less than their shiny trucks.
> banning all civilian air travel
If we calculate fuel economy per mile, planes do pretty good for long trips. Planes are (obviously) very aerodynamic and light. Getting up to altitude takes a lot of fuel but, once there, they sip fuel. Mind you that there are general aviation planes running with standard gasoline that are most likely more efficient than a 23 year old trucks and, most likely, even more efficient than new trucks, once you consider the speed they travel at and how light and aerodynamic they are compared to a truck.
And, since you said All civilian air travel, that includes airliners. Now we are talking efficiency per set per mile. The numbers are actually pretty good; you can look them up.
All that said, can we, collectively, stop antagonizing people that live a different lifestyle than we do, for no reason?
>> I wish to point out that those who fly private airplanes (including those using leaded avgas) are the most likely to demand I stop driving my 23 year old pickup.
> Citation needed. Did you actually experience this, or is this a hypothetical?
> I do not know why pilots would be giving you a hard time with a truck given that most general aviation aircraft in operation are older than your truck.
The airframe likely is older than the truck, but the engine is usually considerably newer. GA aircraft engines require overhauls or replacement be done every 1200-2000 hours of run time.
Overhauling an engine every 2000 hours does not change that it is a 1960s design which relies on a very rich mixture and stupidly high octane fuels to not blow itself up to make what would today be very mediocre performance figures.
Rotax has some newer designs that are fuel injected, have modern piston head designs, and sometimes have turbochargers, and those represent what a "new" aircraft engine looks like.
While this is true, the frequency and ease in which engines are swapped does allow the potential for innovation to creep into the space. We’ve made ICE engines smaller and more efficient over the last 3/4 of a century - but the FAA doesn’t seem to car about GA and likely won’t let anything innovative into non-experimental aircraft, which is a shame. Their argument is always safety, but we have ways to test for that and most of the GA engine designs we still see are from an era where they were not as concerned and were effectively grandfathered in.
A curious assertion? I don't know that many pilots anymore, but I don't recall that being an anti car crowd. They were usually mechanical enthusiast of all types.
I'd love for the plane I fly to use G100UL, which is unleaded aviation gas, but it's just not feasible. Unleaded aviation gas is truly wonderful – it extends engine lifespan and reduces the frequency of oil changes. Sadly, after talking to GAMI at Oshkosh, they said I can't run it due to the high compression ratio.
People will still travel long distances, and because American passenger trains aren't of very high quality, they will be driving. The gallons per seat per mile of airliners are way better than basically any car, for example the 747 has 91 Passenger-miles/US gallon. Even some of the better gas cars struggle to get above 30 miles per gallon.
Additionally, its not really a massive win. Air traffic only makes up 8% of less than 30% of American emissions. Cars, on the other hand, make up more than 75% of that same 30%[0]. Switching to aircraft might actually make more sense for the environment.
I wouldn't expect the ban to occur in isolation of other actions. If we're at the point where personal air travel is being axed, then fuel taxes for automobiles would likely also be prohibitive.
But here in Canada our carbon tax is facing strong opposition from populists, and I expect that the next Government is likely to axe it. The current Government is already putting in place boutique exclusions; for instance, home heating fuel is excluded for the next three years. As an alternative, to discourage a major common form of driving, we should consider ways in which to make businesses find operating office space impossibly expensive.
Why not a ban on personal travel outright? No one needs to take a vacation, and you don’t strictly need to see your family either.
Maybe we could have some kind of a permitting system where you could apply for permission to travel to see, for instance, your dying parent. But you would need to submit a letter from a doctor stating they are likely to die in the next 7-14 days, of course.
How about a ban on recreational activities like hiking and skiing? If we’re serious about this being an existential threat, this should be an easy decision.
The great thing about that idea is that I don't care about personal air travel, so a ban costs me nothing. I can feel good about myself without needing to think about my own excesses.
The airplanes this is about mostly are relatively fuel efficient. They burn a lot of gas per hour, but they also go faster than a car and so per distance efficiency is about the same as a gas car.
Jets are different - they go a lot faster. Commercial jets when full are about the same as a small car. Private jets generally have much less people on board, if you filled them to capacity with people they do well.
Most everyone I know in aviation, especially on the propeller/piston end of the spectrum, tend very much "live and let live" in mentality and politics, and many of them tend towards gear-head/old car enthusiast.
There are other demographic categories of people who are far more likely to demand you stop driving that pickup.
No need to ban it, but I'm happy to support a carbon tax on aviation equivalent to the current market cost of CCS, so something like $200/t.
So, for instance, Elon Musk's private jet is estimated to have emitted 2,112 tons in 2022. Elon would have to pay a $400,000 carbon tax.
Ideally these taxes would flow through fuel, but that presents some challenges, since planes can re-fuel in jurisdictions without those taxes, although that's certainly harder to do in the United States. I think in the US, it might be hard enough to do that that just taxing the aviation fuel is fine.
The only problem is that all the fuel used in all of private aviation is a drop in the bucket of total carbon emissions. It's not low-hanging fruit. It's not really fruit at all.
Yes, but I was commenting about the idea of a "carbon tax" on aviation fuel.
Now a lead tax might be something to think about if the non-leaded fuel costs more for some reason, lead being more of a concern than carbon in this instance. Tax the lead to make it the more expensive option.
That is the issue at hand in this story, but not really the comment I was replying to (at least primarily).
Leaded avgas is coming from piston-engine aircraft, and I don't think that was really what OP was talking about when commenting about the people flying private aircraft while publicly demanding people stop driving pickup trucks.
For leaded gas, we can simply ban the leaded gas, as the cost of performance in piston-engine aircraft. I'm not really an expert, but at a first glance I see no particularly compelling reason not to do it, so I'm not opposed to that at all.
Carbon is either a pollutant, or it's not. It's either good to put into the atmosphere, or it's not. All you can hope with a carbon tax is to shift the problem around without really accomplishing anything.
It's complicated. Overall it's better to do most anything to protect kids' development, but doing so is tough.
Leaded avgas mainly benefits turbines, which are a minority of GA planes but the majority of avgas users, because they're the always-running commercial subset.
The benefit is in time between overhauls. Every replacement fuel has resulted in more engine deposits and more maintenance -- essentially requiring $20K overhauls at 1,500 hours instead of 3K. For non-turbine GA, typically age catches up to the engine before hours, but for commercial turbines it can be a make-or-break decision, since a company might own only one or two.
Reid-Hillview airport in San Jose is an example of an airport closed over leaded fuel concerns, because they reportedly found an increase in lead in children's blood in a few who lived right next to the airport. That increase was minimal compared to elevated levels found in Oakland and elsewhere due to ingestion of 60+-year-old leaded paint, but it's essential to remove whatever sources there are.
The EPA has often complained, but the FAA has persisted. This particular move is noise before the next election (timed for the just-approved FAA appointee). It's unclear if it will result in anything faster than the decades-delayed process already in play, but it does give communities huge leverage in their lawsuits.
Local airports often have a lot of land being used for essentially nothing. When local communities take federal money to develop or maintain airports, they legally agree that the airport is to remain in near-perpetuity. It can take decades of refusing federal money to get out from those obligations. The redevelopment opportunity presented by closing an airport in San Jose or Santa Monica is in the billions of dollars. So there are strong economic interests supporting anything that turns a community against the local airport. And since few people want to have planes overhead, those neighborhoods are typically lower-income and often under-represented politically, raising environmental justice concerns and making for concealed politics as monied interests fund advocacy campaigns and scientific research.
Commercial turbine operators, GA owners, and local businesses using general aviation typically have fixed assets that commit them to protecting the airport.
The price of avgas runs 50-150% over automotive fuel. For refiners, it's a production shift and a run that lasts 1-2 weeks per year (and hence some storage costs as well). They also have fixed assets, though distribution networks have in some cases been outsourced in anticipation of moving in or out of the avgas market. They do it mostly to keep people happy, since it's not a big profit maker.
A big issue is ethanol. It's seasonally mixed into automotive fuel almost everywhere, but it attacks most of the current fuel systems. With engine re-certification for avgas, there are only 1-3 manufacturers running a few engines through time on test beds and some pilot programs. That's much, much easier than retrofitting fuel systems of many, many models of planes. In most cases, the manufacturer is no longer in operation, or they would love to see the old planes die so they can sell new ones (often having bought minimal name and assets out of bankruptcy).
Electric is unlikely to replace turbine ICE unless the energy density improves in ways that would transform the entire world. It's more likely smaller jet engines could replace them, but it's not clear who would do that engineering for a relatively small market.
So a pessimistic prediction is that this might help some local land grabs, but is not likely to help a lot of kids. Let's hope for more than that.
> Leaded avgas mainly benefits turbines, which are a minority of GA planes but the majority of avgas users,
Eh? No. Turbine (i.e. jet) aircraft engines burn Jet-A, which is essentially kerosene and doesn't have any lead in it. Jet-A is not avgas. Reciprocating piston aero engines use 100 octane low lead avgas (today). That's the subject of the EPA thing in the article.
Yeah, the original post has to be the most poorly informed and off target post in this thread.
Leaded gas should never be burned in a turbine or for that matter any engine not specifically called for it. I've known motorcycle owners who do it, the spark plug, cylinder head, & piston wind up covered in a layer of lead
Lead deposits happen for aviation engines too. Wouldn't surprise me if at some point after leaded fuel is gone, engine manufacturers start to increase TBO intervals.
It's not complicated at all. On one hand we have a mostly recreational activity. On the other hand we have a massive public health and environmental issue.
If that's the only angle you care about, then consider that a population free of lead-induced brain damage provides a stronger economy in the long run as more of them are able to enter the workforce rather than prison [1] or a grave [2].
I enjoy AVWeb on YT for AV news (really, I just enjoy the humor/personality of Paul Bertorelli lol), here are a few insightful videos that summarize the story:
The Long, Twisted And Slightly Ridiculous Story of Avgas Part 1 (14:22) https://www.youtube.com/watch?v=9F-WngVMJBQ
Part 2 (15:15) https://www.youtube.com/watch?v=Mvse4Xhzwuk
and
G100UL Approved Now What? (When the FAA approved the first unleaded 100-octane avgas a year ago) https://www.youtube.com/watch?v=ibIkuyBL9i8