Avgas Endangerment Finding Expected This Week


The EPA is expected to formally issue an endangerment finding on leaded aviation fuel as early as Wednesday. In response, the Eliminate Aviation Gasoline Lead Emissions (EAGLE) initiative will be briefing the aviation media Wednesday on what life might be like in the wake of the finding. An endangerment finding gets the ball rolling on regulatory and legislative action to get rid of that danger, and EAGLE wants to stay ahead of the impacts on general aviation as it facilitates the move to unleaded aviation gasoline.

“We believe it is important to understand the finding, what it will mean to general aviation, what it will not mean, and the next steps in the ongoing commitment to eliminate lead from avgas,” EAGLE said in its invitation. Last week EAGLE held a similar briefing to explain the process and give the issue some pre-announcement profile. This week’s briefing, which will happen with NBAA-BACE as a backdrop, will include an expanded list of industry officials whose facilities and businesses will be directly affected by the finding. AVweb will be sitting in and reporting on the results. The EPA did not immediately respond to a confirmation request from AVweb.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.

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  1. As a (recent) plane owner – running a 1999 carbureted Lycoming O-360, I’ve been told my engine can run on unleaded and that doing so would greatly reduce the chances of spark plug fouling. I’ve wondered if this is really true and what additional considerations (other than the obvious one of finding aviation grade unleaded) there are. Could most existing GA piston engines be modified for unleaded at their standard overhaul interval – or are some completely intolerant of unleaded fuel?

    • Aviation fuel is a different blend; it has to be better at not boiling on hot days and at altitude. It also has to be stable enough to sit in fuel tanks in a wing with vents that are directly open to the atmosphere for many months at a time. It also has to reject absorbing water and not corroding sealants and gaskets used in the tanks, lines and carburetor.

      That being said, if they just removed the lead from AvGas, you’re engine would be better off and the “crisis” would be over. Unfortunately, simple answers have avoided the FAA/GA for going on some 40 years now.

    • As I understand it, most if not all GA piston engines could be modified to burn UL94 by installing different pistons that would slightly reduce the compression ratio. This would result in a power loss of several percent, roughly equivalent to increasing the effective density altitude by about 1,500 ft.

      However… It would require an STC, which would be expensive. Even if the FAA waived the STC requirement, the manufacturers would have to do their homework on the change, and that would be expensive.

      Then, the pistons would have to be replaced. That requires removing the cylinders, so it’s something you’d do at overhaul, as you suggest.

      Waiting until overhaul means we’d have a large population of aircraft, for a long time, that still need 100LL, so the transition would take many years to complete.

      So: less power, more expense, and a very long transition.

      Here’s the thing: back in the dawn of time, the C152 was certificated with a Continental engine that not only didn’t need lead, it was routinely fouled by lead. Most pilots flying today had not yet been born then – and we still haven’t made the transition. The big mistake, in retrospect, was continuing to build motors that required 100LL. If that hadn’t happened, there would be a relatively small conversion requirement today, for antique engines.

      But it did happen, and those of us who don’t need or want lead in our fuel are stuck with it, at least until some other highly toxic replacement we ALSO don’t need, can be found.

      • Thomas,
        The information about lowering compression on most GA engine’s is incorrect. Cessna and Lycoming have already approved the use of 94UL for the 172S with the IO-360L2A. Now for some turbocharged or supercharged aircraft the boost would/maybe be limited to operate on 94UL but for everyone else you can safely operate on 94UL and not have any issues or loss of power. Current fuel available by Swift have proven to be a perfect replacement without the drawbacks of leaded fuel (lead corrosion, oil contamination, valve guide buildup) Tetraethyl lead was a necessity in the 50’s/60’s for several mechanical reasons (prevent valve seat erosion, anti-knock for supercharged radial engines) but times and equipment have changed dramatically. With updating avionics with engine monitoring one can easily and safely operate Hi-Power engines. The biggest point I would like to get accomplished is how uneducated comments drag us back into the dark ages and prevent us as pilots to enjoy something we love so much..

        • So if I understand correctly, you’re saying that most of the engines could be operated on 94UL without even changing the compression ratios, by changing the boost limits and engine monitoring?

    • Yes, most aircraft engines would run much better on unleaded fuel. Lead causes spark plug fouling and contaminates the oil. In people, lead poisoning causes lower mental and anti-social behavior. While I doubt that the amount that GA uses causes harm to the general public, I worry about people pumping fuel and maybe mechanics. One of my local airstrips which has mostly experimental aircraft with Rotax engines sells only unleaded fuels. We had an incident about a month ago when a plane with a Rotax engine was brought in for service. On a test flight, one cylinder quit firing because of spark plug fouling which was linked to the use of leaded fuel.

      Some high-performance and especially turbo-charged aircraft engines require higher octane fuels which is because out-dated air-cooled aircraft engines have hot spots. One solution would be water-alcohol injection with the amount depending on manifold pressure. Technically, this would fairly simple except that the FAA would need to be involved. This system was used in WW2 aircraft and with Reno racers. It would require a second tank and another fluid to be replenished but not worse than DEF for diesel engines.

      • Yeah, there are any number of solutions. Unfortunately, every one involves the FAA and people who can be sued nearly every time a plane crashes whether it’s even remotely possible they had anything to do with it.
        That means for any solution we have to figure how to pay off the insurance for everyone AND satisfy every obstinate bureaucrat involved as well.
        As recently demonstrated by the House Republicans and many third world communists back in the Cold War, this means we will do exactly whatever the most obstinate people involved desire, and they don’t even have to reveal that until they deem to do so.
        I’m becoming someone willing to yell and scream before they win, because I’m getting tired of yelling and screaming afterwards.

        • Similar to me in screaming at all the irresponsible voters who vote for despots like Joey. Most all easily throw blame at the wrong party to justify their ignorance. With that they are ruining this country and setting it back to the dark ages. I continue to yell and scream for those to stop because I refuse to be committed to an internment camp with you or anyone else that subjected us to by their ignorant voting policy.
          Get the right evidence before blaming.

    • Just for the record, those of us at Ground Zero for “Lead Wars” at Reid Hillview Airport in San Jose CA have been at an airport where sale of 100LL has been prohibited since the end of 2021. And our Comanche 180 based there (Lycoming O-360-A1A) has been happily burning Swift’s UL94 Avgas since October of 2021, with cleaner oil and no plug fouling compared to 100LL. So have all the training aircraft of all 4 major flight schools at the airport. Swift’s UL94 is essentially 100LL minus the lead. And their unleaded 100R is nearing final testing and ASTM certification and should be available in limited markets sometime in 2024. For all those Cirrus and Bonanza and T-210 owners, there is going to be a 100 octane unleaded fuel on the market sooner than 2030 that won’t require new pistons or altered timing or any other physical mods beyond potentially a paper STC.

      • Happy to hear about the 0-360 A1A and Swift UL94 – because that’s the engine I have! Also, it’s in an Vans RV (Experimental) which gives me more flexibility than those flying certified aircraft (I beleive that would also apply to my fuel selection).

    • Thanks to everyone that provided insight into the potential effect of switching to a no-lead altrenative. Fortunately for me it seems my Lycoming 0-360 A1A is well positioned to use Swift’s UL94. Also, I now own a Vans RV (Experimental) which likely means I wouldn’t need an STC to make the change if forced to in the future. As an aside, I’m still learning about – and amazed by – the flexibility owning an Experimental gives me. Frankly, after 20+ years of flying Archers, I’d be hard pressed to ever buy a certified aircraft if I can find an Experimental that meets my needs.

  2. When a government directs findings to what they want and then uses that to force people to comply, it’s usually called subjugation.

    I’ve read the “study” and who conducted it and (like co2 research) began with a conclusion already written.

  3. As with any study, look to see who is writing the check. I recently saw the statement “ Science is irrefutable – scientists go to the highest bidder.”

    • Man, that’s totally wrong, and you obviously don’t know scientists!

      They are not so easily swayed by a single big check. They do the bidding of the powerful who offer long term security and benefits. Think of the academy as something like a Ferrari dealership. You can’t just walk in and get your name on the list for the next great thing. You have to be somebody, or at least be approved of in the right circles.

  4. This whole thing is just absurd. We all saw the beginning of the end of leaded gasoline in the 1970’s – at least 40 years ago. Cars have been totally unleaded since 1/1/96. Pilots like to talk about the really small percentage of gas that piston airplanes burn (out of the total amount of gasoline burned in the US), but what about the really small percentage of piston aircraft engines that haven’t had a major overhaul since 1995? Or since 1980, when we know the lead was eventually going away? There really is no excuse for GA not to have completed this change 10 or 15 years ago. But we, as a group (pilots, probably the engine companies, probably the FBO’s) just dug our heels in and said “NOOOO! You can’t make us change!!!! It’s not fair!!!!
    We’ve made our bed, and now we’ll have to lay in it.

    • Pull the bandaid off, it’s time. A few operators will complain for a few months and then it’ll be over. We’ll all be better off when it’s done.

      • How democrats always get their way force it down their throats, dismiss their complaining for a few months and they’ll give it up. Go Brandon.

    • Here we go with the distributed guilt thing again. I was raised by a Catholic woman, and you need better skills to manipulate me like that.

      I’m blaming the FAA first, last, and only. I’ve made the case many times. They have made bringing new engines, fuels, and airframes to market too expensive. They have treated certified GA planes like it was the 60’s without ever taking any risks despite what changed. The story of the Starship pretty much describes the problem.

  5. I don’t see what ya’ll are worrying about. The mythical “they” will just raise the taxes on avgas and then everything will be OK. Simple. $10/gal avgas. Besides, all those electric airplane vaporware ads are showing that there’s an easy alternative. Just run your airplane on D cells. What a crock!

  6. Like electric vehicles being rammed down our throats…follow the money. GAMI received the STC without the assistance of the ‘approved’ pressure groups like AOPA and the like, so, like investigations of favored political animals, any further expansion outside of the ‘approved’ pressure groups will be slow-rolled because they were caught wanting…and there is nothing more vicious than a lobbying group caught wanting.

    This has been in the cards for years. We knew it was coming. But, I wonder just how much of an impact that 100LL seriously has on the environment. And it won’t be fully implemented and a replacement available until the ‘approved’ pressure groups, in concert with the oil companies (they couldn’t really give a flying fig about avgas, let’s face it…worldwide, avgas’ effect on their revenue is in the rounding error of the balance sheets) and the bureaucrats have all the wordsmithing done and proper ‘donations’ made for whatever flavor of the month favorite agenda item is satisfied.

    IOW, politics as usual, regardless of party affiliation.

  7. Faa to pull their heads out end just do it. Something that should have been done 40 years ago.

    What else is going on in GA besides lead and batteries? Those horses are a bloody pulp already.

  8. Lots of braying from those not involved in aviation for SUPPORT of the ban–but hardly ANY comments from pilots and aircraft owners that SUPPORT the ban–(or for the equally unpopular support for “electric airplanes” as well.)

    Imagine telling car drivers that “you can’t drive your CAR or HEAT YOUR HOME unless it meets these new standards that WE THINK are important!” That kind of ban would be unenforceable.

    How about a timeline for conversion–say “10 years.”
    Or perhaps a special authorization–like the lack of modern anti-pollution devices on autos over a certain age? These vehicles can still have limited use if licensed as “antiques.”
    Or–if they REALLY believe this is a major problem–a stipend for a set period of time for aircraft owners to convert their aircraft–it gets the job done NOW, while mitigating the cost to owners that spent the money to buy government-approved engines and parts.

    The 100 octane scare has claimed its first victims. Here in Minnesota, we have one refinery that makes it–they succumbed to pressure, and stopped making it. Now, we have to have 100 octane trucked up from Kansas (almost 500 miles)–and if they don’t have enough, from Tyler, Texas–over 1000 miles. The other option is to bring it across the border from Manitoba–500 miles, AND pay the import fee. All this extra freight and resulting pollution in the name of “ecology” (and don’t forget that the trailers that haul 100 octane have to be returned to the originating refinery because they can’t be used for anything else–DOUBLING THE COST OF DELIVERY!

    Yet ANOTHER EXAMPLE OF “GOVERNMENT DO-GOODERS”–every one of their proposals has the opposite of the desired effect of cutting pollution.

    • We’ve had 50 years. Lycoming and Continental have held back this transition since the 1980s (Continental even started to make the transition back then, with its smaller motors).

      I’ve had to deal with lead fouling of engines my entire, now very lengthy flying career. I’m way past “enough already”.

      • No, we haven’t been really given any years. If you had tens of millions of dollars to throw away and a few Congressmen on payroll, you had 50 years.
        Why don’t you just give in to what they really want?

        • The Cessna 152 was introduced in 1977 with an engine designed for unleaded fuel – and that engine has had trouble with lead fouling ever since. We all knew unleaded was coming even before the 152 arrived. 1977 is 46 years ago, not 50, but you see my point.
          As for today, many people are already thinking about aircraft engines that burn jet fuel, because the writing is on the wall for avgas; the market for this highly-specialized fuel is just too small.

    • Yes, Jim – imagine telling car drivers that! Imagine telling them that we were going to stop selling leaded gasoline! Oh wait, we did that already and the sky didn’t fall.

  9. The endangerment finding was expected and nearly meaningless. It MAY create some additional sense of urgency, but the reality is it will only trigger the FAA rule making process which will take years. Those that benefit from continuing to sell and burn 100LL as long as possible will continue to drag their feet. I don’t see that this action will motivate government and corporate bureaucrats to reconsider their self-imposed target date of 2030 for a transition from leaded avgas. I hope the market will speak sooner than that.

    • You really believe anyone wants to be selling 100LL? I think what they want is to not have business they invested in suddenly ripped away.

    • That’s pretty much how I see it to. The finding will have no real impact, other than causing more money to be funneled to EAGLE to slow-roll their preferred (i.e. cooperative) industry players’ eventual 100LL replacement formulation (which will probably be inferior to GAMI or Swift’s replacement). But finally getting the lead out of aviation fuel will ultimately be a good thing, even excluding any potential environmental or health reasons.

  10. GAMI figured out how to get the lead out revisiting late WWII formulations.

    It appears to run most any aviation piston engine at about a buck a gallon more than 100LL.

    Others can run most anything wihout ethanol already from a local pump, but transporting it yourself due to the dearth of airport pumps for it are a pain.

    Anything these lobbies, associations and gummint touch is going to raise the $/gallon 50%.

    Rotax options that run ethanol (food, gee, thanks corn lobby) oxygenated also have transport vs dearth of airport pump options- but have the least question marks when lead leaves.

    Just dropping in lower compression pistons will not be a solution for most. I’d sell know amd get into something Rotax 916IS powered and never forward to lead leaving and at airport pumpable options increasing.

    Pricey, but had 30 years to plan ahead.

  11. The issue has been beat to death. Debating it here is pointless. We can only hope that industry and government will finish developing and approving the replacement(s) without further foot-dragging.

  12. I pump my own 91/ETOH free mogas and could run 87 if it were available in a 230 HP continental. 4000 hours one overhaul and the engine remains solid at TBO #2. I flew C150s when AVGAS 80 was plentiful had little or no lead, and the engines ran fine. The current airplane ran 80 as well. The local airport used to have Mogas (after 80 disappeared) and there are a lot of airplanes that used it. I came to town after it was phased out. The FBO mgmt was not happy with me pumping my own and I made a promise to them if they put Mogas in their empty on field tanks, I’d start buying it. No deal.

    I was also around with leaded car gas phase out.

    This is a solvable problem and Continental and Lycoming are capable along with the refiners. Both of them produced 80 Octane powered engines for years. Then engines were redesigned to use 100LL. Why on earth would they go this route 20 years after we phased out lead in automotive fuels? We have known about lead hazards in internal combustion engines for half a century, and yet we are now back to the future of 1972 automobile engines.

    I now run electronic ignition, burn less gas and have not noticed a difference in power or engine performance, with the poor induction systems we have now. And continue to burn mogas, warm summers, cold winters, middle altitudes and low. Engine instrumentation and sensors are a long ways from where they were in ’72 as are engine control modules. It is time Lycoming and Continental call a few Ford engineers and figure it out. Volkswagen diesel engineers can advise the FAA on acceptable methods.

  13. This argument reminds me of lessons learned as an investor. As long as you are in the 51%, all is good; others remain bitching and moaning. Safety first!