7 ms·

In the US avgas (which has similar lead content to pre-phaseout automotive gasoline) is 0.14% of gasoline usage and declining at about 5%/year. Fuel supplied l

by jws 5y ago

In the US avgas (which has similar lead content to pre-phaseout automotive gasoline) is 0.14% of gasoline usage and declining at about 5%/year. Fuel supplied lead is a 99.86% solved problem which is solving itself. Congress has been funding a program to develop lead free fuel which can safely power aviation piston engines, it is ongoing. Intermediate results are largely not available because it is required to protect all commercial entities participating. https://www.faa.gov/about/initiatives/avgas/ https://www.faa.gov/about/initiatives/avgas/ Here is a nice article from someone involved in avgas lead removal: https://www.avweb.com/insider/going-to-the-moon-was-easy-compared-to-100ul/ https://www.avweb.com/insider/going-to-the-moon-was-easy-com...

55873445216111 5y ago
There is a big fight over Avgas going on in San Jose over Reid Hillview airport. Yes, while total use of leaded fuel now makes up a tiny percentage, it is still measurably significant to the people who live in the flight path of a municipal airport. https://sanfrancisco.cbslocal.com/2021/08/18/reid-hillview-airport-san-jose-lead-levels-closing/ https://sanfrancisco.cbslocal.com/2021/08/18/reid-hillview-a...
- outworlder 5y ago
  They are using that as an excuse to close the airport since that's in an area where real state is highly valued. Reid Hillview is a 'relief' airport - that means it is used to shift small GA traffic away from San Jose airport. Those aircraft will not disappear, they will just move to SJC a few miles away and pollute just as much. I seriously doubt that, if the lead was removed overnight, they would change their minds and stop complaining about the airport. This NIMBY fight is older than that. I feel similarly about my HOA who complains about noise pollution from SJC. The airport predates the houses by decades but now it is suddenly a problem. There should be far more outrage about lead in avgas than there is today - maybe then the FAA and EPA would stop bickering and issue some new regulation. Noone wants to take responsibility for the monetary damage and possible disasters stemming from the decision to phase out lead, so decades later we are still looking for the perfect avgas replacement. Meanwhile, European planes are transitioning to other fuels. Either Jet-A or motor gas. Diamond has developed great engines, but when their aircraft are sold in the US, guess which engines they use? People will ask specifically for lead burning Lycoming or Continental. If there was a penalty for doing that, maybe this would change.
  - jeffbee 5y ago
    Counterpoint: if we remove the habitat for civil aviation, it will, in fact, disappear. And we should: it's just a nuisance and serves no real purpose. The idea that civil aviators provide disaster relief, as advocated by those who favor keeping Reid-Hillview open, is completely absurd. A single flight of a real aircraft such as a C-5 at SJC would carry more materiel than 1000s of GA operations.
    - imoverclocked 5y ago
      KRHV and GA in general are part of an ecosystem. There is Angel Flight West for instance which is only possible because of small GA aircraft. A giant aircraft requires a giant amount of fuel, a giant runway and a pilot who has spent a whole lot of hours flying non-commercially. Without GA and small planes, we might also not have sustainable commercial-aviation. My CFI took off to go work for the airlines because of increased demand several months ago. Without GA he may not have had an opportunity to stay with aviation at all. One can not learn everything needed to fly an aircraft in a simulator.
  - RNCTX 5y ago
    Diamond has not developed great engines. There's a video floating around of them quite literally taking stock Mercedes taxi diesels apart and putting different oil coolers on them. The only difference in design besides those oil coolers was their gearbox, which was a joke from day one. Firstly, diesel produces RPMs similar to what a small aircraft propeller wants so even having a gearbox is either a revenue-generating design intended to fail, or an exercise in stupidity. You can tell me which, I honestly don't know. Nor has Diamond developed great aircraft in other aspects, either. Their stick rather than a yoke design was also a cost-cutter, but no one wants to ride around with a piece of metal hitting them in the balls, either. Socata and Cirrus did a much better job of interior design than Diamond, which is why they're still making ever-more-complex airplanes, and Diamond is flirting with bankruptcy. The solution to general aviation getting rid of leaded gas is someone to make small turbines, and the only thing holding that back is the FAA.
    - 5y ago
- imoverclocked 5y ago
  That airport has 100 octane mogas available now. Pilots from other airports have been flying there to fuel up instead of using the 100LL at their local airport. Source: I fly at KRHV
  - idubrov 5y ago
    Interesting. When I was doing my research on ULPower engines (which can burn 100LL, but they would prefer non-leaded), there were very few airports who offered unleaded fuel (UL94). I think, San Carlos / KSQL was the only one I found? I wonder what KRHV closure would mean for unleaded fuel? So everybody would just switch back to 100LL? How is that supposed to help? Wouldn't be more practical (from the point of lead pollution) to enforce non-leaded fuels in those small airports instead? My cursory research shows that lot (?) of these light planes (and, perhaps, the majority of the trainer/weekend hobby aircrafts) would happily burn non-leaded fuel (UL94, for instance), with corresponding STC.
    - outworlder 5y ago
      > Wouldn't be more practical (from the point of lead pollution) to enforce non-leaded fuels in those small airports instead Definitely. It solves one problem. It doesn't solve the "this airport takes space that could be used for parking lots" problem.
andrepd 5y ago
> Intermediate results are largely not available because it is required to protect all commercial entities participating. Ironically, "protecting commercial interests" is why the whole lead fuel catastrophe came to be.
cellularmitosis 5y ago
Can you help us laypersons understand why leaded gas is still needed in GA engines? Is this as simple as using better valve seats or something? I mean cars haven’t needed leaded gas for a long time, why can’t GA aircraft just use modern parts / engines?
- throwaway0a5e 5y ago
  Because they were designed for leaded gas and you can't just modify certified aviation stuff without spending millions on the process of getting your modification approved.
  - MaxBarraclough 5y ago
    I think it's more that most aviation piston engines were originally approved for use with leaded fuel, and things have been slow to change. At least some of them apparently run fine on the right unleaded fuel. https://en.wikipedia.org/wiki/Avgas#UL94_(formerly_94UL) https://en.wikipedia.org/wiki/Avgas#UL94_(formerly_94UL)
- DebtDeflation 5y ago
  Not an aviation guy, but a car guy. Lead has historically been used to raise the octane rating of gasoline. Octane rating expresses the resistance of the fuel to "knock" which is the sudden explosion of the air-fuel mixture inside the cylinder versus a controlled burn and which can damage the engine. The main factor that raises the octane requirement of an engine is the compression ratio (max cylinder volume to min cylinder volume). High compression ratios generate more horsepower but require higher octane fuel. The other thing is that lead lubricates the valve seats preventing excess wear, but that's a solved problem with hardened valve seats.

by jws 5y ago

55873445216111 5y ago

There is a big fight over Avgas going on in San Jose over Reid Hillview airport. Yes, while total use of leaded fuel now makes up a tiny percentage, it is still measurably significant to the people who live in the flight path of a municipal airport. https://sanfrancisco.cbslocal.com/2021/08/18/reid-hillview-airport-san-jose-lead-levels-closing/ https://sanfrancisco.cbslocal.com/2021/08/18/reid-hillview-a...

outworlder 5y ago
They are using that as an excuse to close the airport since that's in an area where real state is highly valued. Reid Hillview is a 'relief' airport - that means it is used to shift small GA traffic away from San Jose airport. Those aircraft will not disappear, they will just move to SJC a few miles away and pollute just as much. I seriously doubt that, if the lead was removed overnight, they would change their minds and stop complaining about the airport. This NIMBY fight is older than that. I feel similarly about my HOA who complains about noise pollution from SJC. The airport predates the houses by decades but now it is suddenly a problem. There should be far more outrage about lead in avgas than there is today - maybe then the FAA and EPA would stop bickering and issue some new regulation. Noone wants to take responsibility for the monetary damage and possible disasters stemming from the decision to phase out lead, so decades later we are still looking for the perfect avgas replacement. Meanwhile, European planes are transitioning to other fuels. Either Jet-A or motor gas. Diamond has developed great engines, but when their aircraft are sold in the US, guess which engines they use? People will ask specifically for lead burning Lycoming or Continental. If there was a penalty for doing that, maybe this would change.
- jeffbee 5y ago
  Counterpoint: if we remove the habitat for civil aviation, it will, in fact, disappear. And we should: it's just a nuisance and serves no real purpose. The idea that civil aviators provide disaster relief, as advocated by those who favor keeping Reid-Hillview open, is completely absurd. A single flight of a real aircraft such as a C-5 at SJC would carry more materiel than 1000s of GA operations.
  - imoverclocked 5y ago
    KRHV and GA in general are part of an ecosystem. There is Angel Flight West for instance which is only possible because of small GA aircraft. A giant aircraft requires a giant amount of fuel, a giant runway and a pilot who has spent a whole lot of hours flying non-commercially. Without GA and small planes, we might also not have sustainable commercial-aviation. My CFI took off to go work for the airlines because of increased demand several months ago. Without GA he may not have had an opportunity to stay with aviation at all. One can not learn everything needed to fly an aircraft in a simulator.
- RNCTX 5y ago
  Diamond has not developed great engines. There's a video floating around of them quite literally taking stock Mercedes taxi diesels apart and putting different oil coolers on them. The only difference in design besides those oil coolers was their gearbox, which was a joke from day one. Firstly, diesel produces RPMs similar to what a small aircraft propeller wants so even having a gearbox is either a revenue-generating design intended to fail, or an exercise in stupidity. You can tell me which, I honestly don't know. Nor has Diamond developed great aircraft in other aspects, either. Their stick rather than a yoke design was also a cost-cutter, but no one wants to ride around with a piece of metal hitting them in the balls, either. Socata and Cirrus did a much better job of interior design than Diamond, which is why they're still making ever-more-complex airplanes, and Diamond is flirting with bankruptcy. The solution to general aviation getting rid of leaded gas is someone to make small turbines, and the only thing holding that back is the FAA.
  - 5y ago
imoverclocked 5y ago
That airport has 100 octane mogas available now. Pilots from other airports have been flying there to fuel up instead of using the 100LL at their local airport. Source: I fly at KRHV
- idubrov 5y ago
  Interesting. When I was doing my research on ULPower engines (which can burn 100LL, but they would prefer non-leaded), there were very few airports who offered unleaded fuel (UL94). I think, San Carlos / KSQL was the only one I found? I wonder what KRHV closure would mean for unleaded fuel? So everybody would just switch back to 100LL? How is that supposed to help? Wouldn't be more practical (from the point of lead pollution) to enforce non-leaded fuels in those small airports instead? My cursory research shows that lot (?) of these light planes (and, perhaps, the majority of the trainer/weekend hobby aircrafts) would happily burn non-leaded fuel (UL94, for instance), with corresponding STC.
  - outworlder 5y ago
    > Wouldn't be more practical (from the point of lead pollution) to enforce non-leaded fuels in those small airports instead Definitely. It solves one problem. It doesn't solve the "this airport takes space that could be used for parking lots" problem.

andrepd 5y ago

> Intermediate results are largely not available because it is required to protect all commercial entities participating. Ironically, "protecting commercial interests" is why the whole lead fuel catastrophe came to be.

cellularmitosis 5y ago

Can you help us laypersons understand why leaded gas is still needed in GA engines? Is this as simple as using better valve seats or something? I mean cars haven’t needed leaded gas for a long time, why can’t GA aircraft just use modern parts / engines?

throwaway0a5e 5y ago
Because they were designed for leaded gas and you can't just modify certified aviation stuff without spending millions on the process of getting your modification approved.
- MaxBarraclough 5y ago
  I think it's more that most aviation piston engines were originally approved for use with leaded fuel, and things have been slow to change. At least some of them apparently run fine on the right unleaded fuel. https://en.wikipedia.org/wiki/Avgas#UL94_(formerly_94UL) https://en.wikipedia.org/wiki/Avgas#UL94_(formerly_94UL)
DebtDeflation 5y ago
Not an aviation guy, but a car guy. Lead has historically been used to raise the octane rating of gasoline. Octane rating expresses the resistance of the fuel to "knock" which is the sudden explosion of the air-fuel mixture inside the cylinder versus a controlled burn and which can damage the engine. The main factor that raises the octane requirement of an engine is the compression ratio (max cylinder volume to min cylinder volume). High compression ratios generate more horsepower but require higher octane fuel. The other thing is that lead lubricates the valve seats preventing excess wear, but that's a solved problem with hardened valve seats.