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It’s definitely the only reason leaded fuel is still being burned. No one has been able to find a practical replacement anti-knock compound, and apparently it’

It’s definitely the only reason leaded fuel is still being burned. No one has been able to find a practical replacement anti-knock compound, and apparently it’s been decided that the safety tradeoff is worth it (slightly poisoning the atmosphere vs. risk of in-flight engine failures).

sokoloff 8y ago
There are a couple of companies working on a high-octane unleaded aviation fuel. The FAA PAFI program has largely fallen apart (my interpretation of what’s going on), but there seems to be some hope that GAMI’s G100UL (unleaded) may be workable as a drop-in replacement for today’s 100LL (“low lead” or “avgas”) and a lesser chance (again, IMO) of Swift’s fuel being viable. G100UL is flying in some experimental aircraft today. (These include originally factory-built airplanes/engines converted to experimental use for the purpose of this testing.) It’s probably 5+ years away in the very best case, as there’s a science/engineering problem to clear, but then an even larger regulatory hurdle remaining to clear, as the majority of avgas sold today is sold for airplanes only certified to run on 100LL, so there’s a certification change needed at some level. If that doesn’t apply to the whole fleet, it’s a logistics nightmare for airport fuel vendors. Disclaimer: I casually know one of the principals at GAMI and have visited their test lab. I have no financial connection to them, however. I want them (or anyone else with an all-fleet solution) to succeed so that I can stop burning leaded avgas.
- AWildC182 8y ago
  Swift also has 94UL which I believe all the Cirrus aircraft are certified for and I imagine most of the other high performance turbos could get an STC for. There's also the mogas STCs if we could drop the stupid ethanol corn subsidy. Personally I'm currently working on an EAB that will run E10 without issue because I'm so sick of the 100LL shit. There's a LOT of lead in 100LL (despite the name) and aircraft operations naturally expose you to a lot of it.
  - sokoloff 8y ago
    I mentioned Swift as well, but don’t think they have as good a chance to be an all-fleet fuel. The Cirrus factory turbos are low compression engines (7.5:1). That gives a greater margin against detonation (at the cost of efficiency). That won’t extend to 8.5:1 compression, big-bore engines near as easily, whether turbo or normally aspirated. (This also means that I doubt it will work in the Tornado Alley turbo-normalized Cirrus.) I too want to get the lead out of my life, especially since my kids fly in the airplane and are going to have exposure to it incidentally, even as I try to minimize it. It may well end being faster to just make more money and switch to Jet-A than to wait for a viable unleaded fuel to take over the market.
  - jabl 8y ago
    AFAIU 94 is about what you get if you remove the lead from 100LL.
- jabl 8y ago
  Here's a recent article about the PAFI program: https://www.avweb.com/blogs/insider/Unleaded-Avgas-All-on-the-Same-Page-Not-231381-1.html https://www.avweb.com/blogs/insider/Unleaded-Avgas-All-on-th...
maxerickson 8y ago
There's also no one spending money getting replacement engines that don't need lead rated. Like if you wanted to make a safety tradeoff you'd just ban general aviation (Imagine, they poison everyone a little bit, by taking pretty high personal risks).
- AWildC182 8y ago
  That's going to be a no-go with the current wildfire situation, full stop. GA is actually pretty important and the US has enjoyed a lot of benefits from having a strong GA sector. Keep in mind that the US trains the lions share of the world's pilots because in the rest of the world it's either too expensive or too restrictive (many governments don't like the idea of people having access to airplanes). Either way though, I'm going to make you defend the personal risk statement as ground fatalities from GA accidents are exceedingly rare by any reasonable metric. There is a lot of money going into replacement engines but they're mostly diesel since the most dominant fuel in aviation is Jet-A (essentially diesel/kerosene). These have found some success in Europe where 100LL is much more expensive as the operating costs of the diesels is much greater given their complexity, maintenance needs, and initial acquisition costs.
  - sokoloff 8y ago
    Indeed. In addition to fire fighting and pilot training, avgas burning aircraft provide critical transport in rural areas and a portion of the crop-dusting fleet is piston-powered. Many more people are killed by dog bites in America than ground GA fatalities (turbine and piston combined). I’d no sooner make a safety argument to ban dogs than piston airplanes.
    - maxerickson 8y ago
      I was talking about the people in the plane exposing themselves to risk by flying, not ground fatalities, so uh? I wonder how "high personal risks" would lead to the misunderstanding. It looks like crashes result in about 300 annual deaths (of people on the planes) and dog bites 20 or 30. It seems that flying in a small plane is only somewhat more dangerous than driving the similar distance. But driving isn't really safe in the US either.

sokoloff 8y ago

There are a couple of companies working on a high-octane unleaded aviation fuel. The FAA PAFI program has largely fallen apart (my interpretation of what’s going on), but there seems to be some hope that GAMI’s G100UL (unleaded) may be workable as a drop-in replacement for today’s 100LL (“low lead” or “avgas”) and a lesser chance (again, IMO) of Swift’s fuel being viable. G100UL is flying in some experimental aircraft today. (These include originally factory-built airplanes/engines converted to experimental use for the purpose of this testing.) It’s probably 5+ years away in the very best case, as there’s a science/engineering problem to clear, but then an even larger regulatory hurdle remaining to clear, as the majority of avgas sold today is sold for airplanes only certified to run on 100LL, so there’s a certification change needed at some level. If that doesn’t apply to the whole fleet, it’s a logistics nightmare for airport fuel vendors. Disclaimer: I casually know one of the principals at GAMI and have visited their test lab. I have no financial connection to them, however. I want them (or anyone else with an all-fleet solution) to succeed so that I can stop burning leaded avgas.

AWildC182 8y ago
Swift also has 94UL which I believe all the Cirrus aircraft are certified for and I imagine most of the other high performance turbos could get an STC for. There's also the mogas STCs if we could drop the stupid ethanol corn subsidy. Personally I'm currently working on an EAB that will run E10 without issue because I'm so sick of the 100LL shit. There's a LOT of lead in 100LL (despite the name) and aircraft operations naturally expose you to a lot of it.
- sokoloff 8y ago
  I mentioned Swift as well, but don’t think they have as good a chance to be an all-fleet fuel. The Cirrus factory turbos are low compression engines (7.5:1). That gives a greater margin against detonation (at the cost of efficiency). That won’t extend to 8.5:1 compression, big-bore engines near as easily, whether turbo or normally aspirated. (This also means that I doubt it will work in the Tornado Alley turbo-normalized Cirrus.) I too want to get the lead out of my life, especially since my kids fly in the airplane and are going to have exposure to it incidentally, even as I try to minimize it. It may well end being faster to just make more money and switch to Jet-A than to wait for a viable unleaded fuel to take over the market.
- jabl 8y ago
  AFAIU 94 is about what you get if you remove the lead from 100LL.
jabl 8y ago
Here's a recent article about the PAFI program: https://www.avweb.com/blogs/insider/Unleaded-Avgas-All-on-the-Same-Page-Not-231381-1.html https://www.avweb.com/blogs/insider/Unleaded-Avgas-All-on-th...

maxerickson 8y ago

There's also no one spending money getting replacement engines that don't need lead rated. Like if you wanted to make a safety tradeoff you'd just ban general aviation (Imagine, they poison everyone a little bit, by taking pretty high personal risks).

AWildC182 8y ago
That's going to be a no-go with the current wildfire situation, full stop. GA is actually pretty important and the US has enjoyed a lot of benefits from having a strong GA sector. Keep in mind that the US trains the lions share of the world's pilots because in the rest of the world it's either too expensive or too restrictive (many governments don't like the idea of people having access to airplanes). Either way though, I'm going to make you defend the personal risk statement as ground fatalities from GA accidents are exceedingly rare by any reasonable metric. There is a lot of money going into replacement engines but they're mostly diesel since the most dominant fuel in aviation is Jet-A (essentially diesel/kerosene). These have found some success in Europe where 100LL is much more expensive as the operating costs of the diesels is much greater given their complexity, maintenance needs, and initial acquisition costs.
- sokoloff 8y ago
  Indeed. In addition to fire fighting and pilot training, avgas burning aircraft provide critical transport in rural areas and a portion of the crop-dusting fleet is piston-powered. Many more people are killed by dog bites in America than ground GA fatalities (turbine and piston combined). I’d no sooner make a safety argument to ban dogs than piston airplanes.
  - maxerickson 8y ago
    I was talking about the people in the plane exposing themselves to risk by flying, not ground fatalities, so uh? I wonder how "high personal risks" would lead to the misunderstanding. It looks like crashes result in about 300 annual deaths (of people on the planes) and dog bites 20 or 30. It seems that flying in a small plane is only somewhat more dangerous than driving the similar distance. But driving isn't really safe in the US either.