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Per https://www.avweb.com/aviation-news/gami-awarded-long-awaited-stc-for-unleaded-100-octane-avgas/ https://www.avweb.com/aviation-news/gami-awarded-long-await

by bdash 5y ago

Per https://www.avweb.com/aviation-news/gami-awarded-long-awaited-stc-for-unleaded-100-octane-avgas/ https://www.avweb.com/aviation-news/gami-awarded-long-awaite..., this new unleaded fuel is currently only approved for Cessna 172s with Lycoming engines, with expansion to more aircraft types coming next year.

jcutrell 5y ago
Makes sense - the 172 is one of the most common training planes, getting a TON of low-altitude hours in the pattern. Also because of the low altitude flights 172s will probably run rich. Granted, they aren't burning a ton of fuel per hour - around 8g - but considering the sheer number of 172s out there this will make a reasonable dent in the total fleet of pistons. Though I expect the infra changes to actually support this will take a very long time to actually put in place, and many people will opt for 100LL for a long time because it is all that's available at their local airport or it is cheaper. I own a 182 that has the STC for auto-gas, and barely anyone sells auto-gas on-field. The only other option is to maintain my own tank, but that can't go on trips with me. Still good news in the long run.
- jeffbee 5y ago
  8 gallons of 100LL contains about 4 grams of lead, enough to measurably lower the IQ of over 100000 children.
  - deleted 5y ago
    [deleted]
  - SomeHacker44 5y ago
    Would love to see the source and data on that, given that I use 1000s of gallons of leaded fuel a year.
    - jeffbee 5y ago
      "The study found that for each 5-microgram [per deciliter] increase in blood lead, a person lost about 1.5 IQ points." https://jamanetwork.com/journals/jama/fullarticle/2613157 https://jamanetwork.com/journals/jama/fullarticle/2613157
      - deleted 5y ago
        [deleted]
      - unchocked 5y ago
        You're conflating chronic and acute exposure. Pop epidemiology 101.
    - kube-system 5y ago
      The saving grace is that your exhaust doesn't go directly into the bloodstreams of children, likely most of the lead ends up at other places on earth.
    - wffurr 5y ago
      >> The EPA's own studies have shown that to prevent a measurable decrease in IQ for children deemed most vulnerable, the standard needs to be set much lower, to 0.02 µg/m3. The EPA identified avgas as one of the most "significant sources of lead". Maybe stop?
      - sokoloff 5y ago
        That's the point of the GAMI fuel approval: it provides a practical path to stop using 100LL.
  - throwaway0a5e 5y ago
    You can't just take the mass of the lead and then assume it all winds up in humans. For a given amount of lead output into the atmosphere lead output over an airport is going to get into people's blood a lot less efficiently than lead output in an automotive context.
    - bpodgursky 5y ago
      ... so we're just going to slowly build up base-level contamination in the soil, water, and ecosystem? Let's not?
      - throwaway0a5e 5y ago
        I'm not endorsing lead emissions, just pointing out that emitting them not into people is a lot better than emitting them fairly directly into people. While obviously it would not be ideal to evenly distribute lead evenly throughout the surface of the earth lead is a fairly common element and exists in ground deposits more or less worldwide without poisoning people. It's not as common as iron but it was used for all sorts of thing historically specifically because of how common (and therefore cheap) it is/was.
        henearkr 5y ago
        Well, NO, lead tetraethyl is not naturally present. It's a human-made metallo-organic molecule.
      - lazide 5y ago
        Elemental lead is nearly completely insoluble and very difficult to absorb. If entrained in dirt, even more so. Breathing vapors or aerosolized fine powders isn’t great, but uptake even then isn’t high compared to many other toxic substances - that is usually the dominant form however. It usually requires some kind direct ingestion + acid exposure of a significant amount of lead, or breathing in a large quantity of lead vapor or fine dust to get notable exposure. Which is exactly what you get when every car in a city was burning tetra ethyl lead in large quantities, and/or kids were eating sweet tasting lead paint chips. Leaded AVgas is a concern, but dilution of the resulting lead from combustion gets diluted very widely very quickly resulting in actual low concentrations. And since it’s not ‘every car in the LA basin’, it just isn’t at the scope or scale of a problem you’re making it out to be. We’re probably having bigger issues from all the random new stuff companies put into tires (including carbon nanotubes now), which then gets ground up and dispersed as fine power at the million ton scale every day. Lead is not mobile in typical soil or water environments, and as long as the water isn’t strongly acidic, it settles out and stays where it lands. There is naturally occurring trace lead in most soils - it’s a somewhat common element.
- GekkePrutser 5y ago
  True we'd always run full rich during most of the pattern. Good point.

by bdash 5y ago

jcutrell 5y ago

Makes sense - the 172 is one of the most common training planes, getting a TON of low-altitude hours in the pattern. Also because of the low altitude flights 172s will probably run rich. Granted, they aren't burning a ton of fuel per hour - around 8g - but considering the sheer number of 172s out there this will make a reasonable dent in the total fleet of pistons. Though I expect the infra changes to actually support this will take a very long time to actually put in place, and many people will opt for 100LL for a long time because it is all that's available at their local airport or it is cheaper. I own a 182 that has the STC for auto-gas, and barely anyone sells auto-gas on-field. The only other option is to maintain my own tank, but that can't go on trips with me. Still good news in the long run.

jeffbee 5y ago
8 gallons of 100LL contains about 4 grams of lead, enough to measurably lower the IQ of over 100000 children.
- deleted 5y ago
  [deleted]
- SomeHacker44 5y ago
  Would love to see the source and data on that, given that I use 1000s of gallons of leaded fuel a year.
  - jeffbee 5y ago
    "The study found that for each 5-microgram [per deciliter] increase in blood lead, a person lost about 1.5 IQ points." https://jamanetwork.com/journals/jama/fullarticle/2613157 https://jamanetwork.com/journals/jama/fullarticle/2613157
    - deleted 5y ago
      [deleted]
    - unchocked 5y ago
      You're conflating chronic and acute exposure. Pop epidemiology 101.
  - kube-system 5y ago
    The saving grace is that your exhaust doesn't go directly into the bloodstreams of children, likely most of the lead ends up at other places on earth.
  - wffurr 5y ago
    >> The EPA's own studies have shown that to prevent a measurable decrease in IQ for children deemed most vulnerable, the standard needs to be set much lower, to 0.02 µg/m3. The EPA identified avgas as one of the most "significant sources of lead". Maybe stop?
    - sokoloff 5y ago
      That's the point of the GAMI fuel approval: it provides a practical path to stop using 100LL.
- throwaway0a5e 5y ago
  You can't just take the mass of the lead and then assume it all winds up in humans. For a given amount of lead output into the atmosphere lead output over an airport is going to get into people's blood a lot less efficiently than lead output in an automotive context.
  - bpodgursky 5y ago
    ... so we're just going to slowly build up base-level contamination in the soil, water, and ecosystem? Let's not?
    - throwaway0a5e 5y ago
      I'm not endorsing lead emissions, just pointing out that emitting them not into people is a lot better than emitting them fairly directly into people. While obviously it would not be ideal to evenly distribute lead evenly throughout the surface of the earth lead is a fairly common element and exists in ground deposits more or less worldwide without poisoning people. It's not as common as iron but it was used for all sorts of thing historically specifically because of how common (and therefore cheap) it is/was.
      - henearkr 5y ago
        Well, NO, lead tetraethyl is not naturally present. It's a human-made metallo-organic molecule.
    - lazide 5y ago
      Elemental lead is nearly completely insoluble and very difficult to absorb. If entrained in dirt, even more so. Breathing vapors or aerosolized fine powders isn’t great, but uptake even then isn’t high compared to many other toxic substances - that is usually the dominant form however. It usually requires some kind direct ingestion + acid exposure of a significant amount of lead, or breathing in a large quantity of lead vapor or fine dust to get notable exposure. Which is exactly what you get when every car in a city was burning tetra ethyl lead in large quantities, and/or kids were eating sweet tasting lead paint chips. Leaded AVgas is a concern, but dilution of the resulting lead from combustion gets diluted very widely very quickly resulting in actual low concentrations. And since it’s not ‘every car in the LA basin’, it just isn’t at the scope or scale of a problem you’re making it out to be. We’re probably having bigger issues from all the random new stuff companies put into tires (including carbon nanotubes now), which then gets ground up and dispersed as fine power at the million ton scale every day. Lead is not mobile in typical soil or water environments, and as long as the water isn’t strongly acidic, it settles out and stays where it lands. There is naturally occurring trace lead in most soils - it’s a somewhat common element.
GekkePrutser 5y ago
True we'd always run full rich during most of the pattern. Good point.