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> some local governments are taking action to ban leaded avgas from being used at airports in their jurisdictions. What happens if a 100LL aircraft lands at su

by p1mrx 5y ago

> some local governments are taking action to ban leaded avgas from being used at airports in their jurisdictions. What happens if a 100LL aircraft lands at such an airport? Do they have to disassemble/tow it, or is there some sort of financial penalty?

lamontcg 5y ago
From what I can google it looks like they ban the sale of leaded avgas at those airports. If you run out of gas at one of those airports I imagine you're purchasing it elsewhere and one way or another arranging for it to be delivered to you at the airport at your expense + hassle.
downrightmike 5y ago
can't it just run unleaded, albeit with slightly less power?
- p1mrx 5y ago
  I assume based on this article that running unleaded would have violated FAA regulations.
  - Robotbeat 5y ago
    I honestly think there should be civil consequences for the FAA slow-rolling the sunsetting of leaded avgas. Red tape is causing very real harm to vast numbers of people.
    - brendoelfrendo 5y ago
      As with many problems with hard-to-see externalities, I think the FAA can't win here. If a plane falls out of the sky because of a fast-tracked approval, or people go out of business because of a fast-tracked ban, then the FAA is the bad guy. The number of people with the ability to assess the impact of atmospheric lead is much smaller.
- colechristensen 5y ago
  In general: no. In aviation you don't do "this should probably work so let's do it". You follow approved guidelines and procedures and only approved guidelines and procedures. When there are a hundred separate things that can go wrong and kill you, you don't stray outside the lines. And the issue isn't only slightly less power.
- noveltyaccount 5y ago
  I know nothing about this and was surprised to learn leaded fuel is still a thing in any gas. Found this: https://www.faa.gov/about/initiatives/avgas/ https://www.faa.gov/about/initiatives/avgas/ Avgas is the only remaining lead-containing transportation fuel. Lead in avgas prevents damaging engine knock, or detonation, that can result in a sudden engine failure. If engine knock can knock you out of the sky, it's probably not something you want to just take a chance with.
  - Robotbeat 5y ago
    Internal risk (&/or cost of a better engine) vs externality of lead slowly poisoning the population.
    - hugh-avherald 5y ago
      The risk of getting hit by a plane whose engine has failed is probably the bigger externality.
- lutorm 5y ago
  To somewhat expand on the other answers: The only reason there are cars that "require 93 octane but can run 87 with lower power" is that they have knock sensors and ECUs that can limit ignition timing to avoid knock. This is a sophisticated system and nothing like it is available in any aviation engine, being designs from the 50s (except maybe some new experimental engines.) The effect of running too low octane fuel in an aviation engine is not "slighly less power", but likely detonation and catastrophic engine failure. And that's why it's a violation of FAA regs to run aircraft on non-approved fuels.
  - tuxinator 5y ago
    Just because something is old doesn't mean it should get a free pass on continuing to use leaded fuel though... there must be other reasons why leaded is still used besides simple knock sensors and ignition timing.
    - Baeocystin 5y ago
      Exhaust valve seats. If you don't use appropriately hardened seats, you need lead to help cushion the wear between the exhaust valves and their seats in the head. If your perfectly reasonable next question is, why aren't standard aircraft engines just built with the appropriate seats, well, then... The answer is low market volume coupled with high regulatory hurdles. There aren't any villains here, just written-in-blood safety regs coupled with a small enough market that there is a lot less money available to fight inertia.
      - mateo1 5y ago
        Exactly. Flying for sport is expensive as it is today because safety has to be a priority (as it should). Add a requirement for new engines or major overhauls on old planes and the cost will spiral out of control. Besides, leaded fuel was a problem when literally every single car on the street was burning it. The total volume of fuel consumed by aviation piston engines is a joke compared to that.
      - ericpauley 5y ago
- Baeocystin 5y ago
  No. The compression ratio is fixed, as is the type of valve seat, and both need specific octane ratings or anti-wear additive, respectively.
- dalrympm 5y ago
  The Pilot Operating Handbook (POH) contains numerous tables that pilots use to calculate what will be safe operating conditions for an aircraft. These include how much runway will be required at specific temperatures/elevations to clear obstacles. Those numbers were based on a 100 octane fuel so if the fuel is changed, those values must be determined once again and I believe that is largely done with flight testing. To do that on the entire fleet would be prohibitive. Without these small planes the misery you experience flying commercial would increased greatly due to the lack of pilots. It's pretty bad as it is.

by p1mrx 5y ago

lamontcg 5y ago

From what I can google it looks like they ban the sale of leaded avgas at those airports. If you run out of gas at one of those airports I imagine you're purchasing it elsewhere and one way or another arranging for it to be delivered to you at the airport at your expense + hassle.

downrightmike 5y ago

can't it just run unleaded, albeit with slightly less power?

p1mrx 5y ago
I assume based on this article that running unleaded would have violated FAA regulations.
- Robotbeat 5y ago
  I honestly think there should be civil consequences for the FAA slow-rolling the sunsetting of leaded avgas. Red tape is causing very real harm to vast numbers of people.
  - brendoelfrendo 5y ago
    As with many problems with hard-to-see externalities, I think the FAA can't win here. If a plane falls out of the sky because of a fast-tracked approval, or people go out of business because of a fast-tracked ban, then the FAA is the bad guy. The number of people with the ability to assess the impact of atmospheric lead is much smaller.
colechristensen 5y ago
In general: no. In aviation you don't do "this should probably work so let's do it". You follow approved guidelines and procedures and only approved guidelines and procedures. When there are a hundred separate things that can go wrong and kill you, you don't stray outside the lines. And the issue isn't only slightly less power.
noveltyaccount 5y ago
I know nothing about this and was surprised to learn leaded fuel is still a thing in any gas. Found this: https://www.faa.gov/about/initiatives/avgas/ https://www.faa.gov/about/initiatives/avgas/ Avgas is the only remaining lead-containing transportation fuel. Lead in avgas prevents damaging engine knock, or detonation, that can result in a sudden engine failure. If engine knock can knock you out of the sky, it's probably not something you want to just take a chance with.
- Robotbeat 5y ago
  Internal risk (&/or cost of a better engine) vs externality of lead slowly poisoning the population.
  - hugh-avherald 5y ago
    The risk of getting hit by a plane whose engine has failed is probably the bigger externality.
lutorm 5y ago
To somewhat expand on the other answers: The only reason there are cars that "require 93 octane but can run 87 with lower power" is that they have knock sensors and ECUs that can limit ignition timing to avoid knock. This is a sophisticated system and nothing like it is available in any aviation engine, being designs from the 50s (except maybe some new experimental engines.) The effect of running too low octane fuel in an aviation engine is not "slighly less power", but likely detonation and catastrophic engine failure. And that's why it's a violation of FAA regs to run aircraft on non-approved fuels.
- tuxinator 5y ago
  Just because something is old doesn't mean it should get a free pass on continuing to use leaded fuel though... there must be other reasons why leaded is still used besides simple knock sensors and ignition timing.
  - Baeocystin 5y ago
    Exhaust valve seats. If you don't use appropriately hardened seats, you need lead to help cushion the wear between the exhaust valves and their seats in the head. If your perfectly reasonable next question is, why aren't standard aircraft engines just built with the appropriate seats, well, then... The answer is low market volume coupled with high regulatory hurdles. There aren't any villains here, just written-in-blood safety regs coupled with a small enough market that there is a lot less money available to fight inertia.
    - mateo1 5y ago
      Exactly. Flying for sport is expensive as it is today because safety has to be a priority (as it should). Add a requirement for new engines or major overhauls on old planes and the cost will spiral out of control. Besides, leaded fuel was a problem when literally every single car on the street was burning it. The total volume of fuel consumed by aviation piston engines is a joke compared to that.
    - ericpauley 5y ago
Baeocystin 5y ago
No. The compression ratio is fixed, as is the type of valve seat, and both need specific octane ratings or anti-wear additive, respectively.
dalrympm 5y ago
The Pilot Operating Handbook (POH) contains numerous tables that pilots use to calculate what will be safe operating conditions for an aircraft. These include how much runway will be required at specific temperatures/elevations to clear obstacles. Those numbers were based on a 100 octane fuel so if the fuel is changed, those values must be determined once again and I believe that is largely done with flight testing. To do that on the entire fleet would be prohibitive. Without these small planes the misery you experience flying commercial would increased greatly due to the lack of pilots. It's pretty bad as it is.