6 ms·

Exactly, I thought lead in fuel was banned a long time ago. This really shouldn't be determined by amateur pilots preference, or even the FAA, it is up to the

Exactly, I thought lead in fuel was banned a long time ago. This really shouldn't be determined by amateur pilots preference, or even the FAA, it is up to the rest of us who are having lead rained down on us, to demand change.

sokoloff 5y ago
Every single pilot flying for the airlines who didn't come via the military learned to fly in piston-engined airplanes. (Where would airline pilots get to the 1500 hours required since the Colgan 3407 crash?) Without a workable substitute for 100LL, banning it is not practical.
- alan-hn 5y ago
  Why is lead a requirement for piston-engine aircraft? Land vehicles seem to be doing just fine without leaded fuel
  - FL410 5y ago
    Because airplanes still use engine designs from 70 years ago. Your next question is: why? Same reason it takes 12 years to get a replacement fuel approved.
  - bombcar 5y ago
    Piston-based aircraft are built to survive numerous failures that wouldn't be a major issue for a land-based vehicle (or a boat) - both of those just kind of sit there when the power generator fails. A plane turns into a glider at that time. Off the top of my head, they mainly use magnetos instead other forms of ignition, have dual mag setups so that one can fail and the engine will still run. And lead-based fuel lubrication is simpler than other forms. Some work is being done on diesel: https://en.wikipedia.org/wiki/Aircraft_diesel_engine#Modern_developments https://en.wikipedia.org/wiki/Aircraft_diesel_engine#Modern_... - and jets of course run off of kerosene basically. And a brand-new plane is really hard to build out cost-wise, much of the aviation fleet is very, very old.
  - sokoloff 5y ago
    There's a multi-part answer. Legally (the subject that requires FAA approval) is that the type-certificate (the legal basis for certification and authority to operate) for these engines specifies the use of 100LL and the standard for 100LL is a composition-based standard, not a performance-based standard. If it doesn't have the prescribed amount of TEL, it's definitionally not 100LL, even if it would meet the performance requirement of the engine. Then, from an engineering standpoint (the subject that companies are working on in order to propose fuels to the FAA via PAFI or GAMI seeking multi-model Supplemental Type Certificate), aircraft engines are stone-age in complexity and are overwhelmingly air-cooled, fixed timing [except during starting], and operate for hours on end at 75%+ of rated power. Your auto is water-cooled, has variable timing, and typically runs at 8-15% of rated power. An aircraft engine has to run reliably with cylinder head temperatures of 460ºF or more (your car's cylinders are much more tightly controlled as a result of the water cooling). Why can't airplanes use a different engine? Airplanes are (legally) certified to use a specific engine and have had extensive flight testing to determine takeoff/landing distances, fuel consumption figures, etc. Those engines are (legally) certified to use a specific fuel [or list of fuels]. Automobile engines have a horrible track record when attempted to be converted to aviation usage. Small, normally aspirated engines are able to run on low-octane, ethanol-free pump gas. The aircraft with high-powered turbo-charged engines represent around 25% of the engines. Because of their higher utilization, those engines burn around 75% of the avgas purchased in a year. (These are the CapeAir fleet, skydive operators, etc.)
    - stoltzmann 5y ago
      >The aircraft with high-powered turbo-charged engines represent around 25% of the engines. Because of their higher utilization, those engines burn around 75% of the avgas purchased in a year. Wouldn't turbo-charged engines burn jet A-1 rather than avgas?
      - cjrp 5y ago
        Turbine engines would, but that's different from turbo-charged (piston) engines.
  - rlpb 5y ago
    Certifications work on a per-aircraft-type and per-engine-type basis. Converting a single aircraft type to a different engine is possible, but every single combination would need to be tested (I think this also includes flight testing) and certified individually. This is not economic. So what remains is for the existing fleet to eventually be retired and replaced by newer aircraft that use newer engines. But most light single piston aircraft being sold today still use older engine designs that require leaded fuel! And newer aircraft are so expensive, it's more economical to keep aircraft from the seventies still going. Newer aircraft are expensive because the certification and insurance requirements are extremely expensive. For example, aircraft manufacturers get sued for accidents caused by pilot error on a regular basis, and so they need insurance for that. "Average cost of manufacturer's liability insurance for each airplane manufactured in the U.S. had risen from approximately $50 per plane in 1962 to $100,000 per plane in 1988, according to a report cited by the Bureau of Labor Statistics,[14] a 2,000-fold increase in 24 years." --https://en.wikipedia.org/wiki/General_Aviation_Revitalization_Act https://en.wikipedia.org/wiki/General_Aviation_Revitalizatio... So light aircraft are stuck running ancient engine designs that require leaded fuel. There is some progress. One manufacturer uses a modern engine that runs on jet fuel (basically a diesel piston engine like in some cars). But that doesn't stop new aircraft being extremely expensive, so it looks like we're still stuck with mostly an old fleet that uses lead for a long time yet.
  - DebtDeflation 5y ago
    None of the above answers actually answer your question. Lead was historically used in gasoline for two reasons - 1) to increase the octane rating (a measure of knock resistance) ans 2) to lubricate the valve seats in the cylinder head. There are multiple other chemical additives that can accomplish #1 (the fuel in the article uses one of them). For #2, the solution in the automotive world starting in the 1970s was to use hardened valve seats that didn't require lead in the fuel to lubricate. The actual answer to your question is "because the FAA won't allow it".
  - p_l 5y ago
    Lead isn't actually a requirement for piston-engine aircraft. It's just that most piston engines available with: 1) world-wide certification 2) world-wide base of trained mechanics 3) already widely deployed (you can't just "swap" engines on a plane design) Are piston engines whose original design happened ages ago when leaded gasoline was the cheapest fuel with necessary performance (and that includes not just octane rating, but also things like evaporation rate at given atmospheric pressure - you don't want your fuel tank to explode due to gasoline vapors). Several newer designs in Europe have been playing around with Diesel engines again, because thanks to being heavier fraction it doesn't have as much evaporation problem of gasoline, and also diesels are by design very tolerant of fuel types. Most importantly, a plane with an aviation diesel engine can just as well use non-ethanol-added diesel from car gas station, or any of the Jet-A1 compatible fuels available on airfields (pretty sure everything that isn't accidental leftover of SR-71 blackbird operation will work just fine).
    - garaetjjte 5y ago
      >also diesels are by design very tolerant of fuel types While combustion process is tolerant, modern high-pressure pumps not so much. I don't think you can run automotive engine on Jet-A without detrimental effects on lifetime of injection system (as it uses fuel as lubricant). Does these aviation diesels use some specially hardened pumps?
- coryrc 5y ago
  There are substitutes that work in most engines. The others can be re-engined. Continuing to spray poison should not be in the table. But plane owners are rich and have money and time to lobby.
  - sokoloff 5y ago
    Most [piston] engines? Yes. Most gallons of avgas bought per year? No (or at least until G100UL has an all-model certification to replace 100LL). I posted more details in a sibling comment here. (I want nothing more than to be able to buy G100UL.)
    - coryrc 5y ago
      https://www.aopa.org/advocacy/advocacy-briefs/regulatory-brief-avgas-100ll-alternatives https://www.aopa.org/advocacy/advocacy-briefs/regulatory-bri... Notice "not poisoning children" is not on their list of requirements. No, just that it doesn't cost you any money. If I just took TEL and sprayed it over your house, I'd be arrested and have to pay tens of thousands for remediation. But do it in a plane? No problem! You don't have to fly. You choose to poison us.
  - jonititan 5y ago
    Most car engines? Yes with the exception of those with ethanol mixed into them. For aircraft engines it's a definite no. Several accidents caused by putting pump gas in aircraft.
- AnIdiotOnTheNet 5y ago
  I'm personally getting kind of sick of "it's not practical" as an excuse for why the general population has to suffer being poisoned and having their environment destroyed. Maybe we just don't need so many pilots and planes if it is so impractical to train and fly them?
  - throwaway0a5e 5y ago
    We can't solve everything all at once. We're simply not that rich. The reason leaded avgas isn't solved yet is because by itself it's a pretty small problem as far as things that are poisoning us and out planet go. Obviously we're making progress, because people still care, but it's not getting resources in the same way that clean electrical energy is because it's a much smaller problem.
- tialaramex 5y ago
  I wouldn't be surprised if there are some pilots who learned in a small (prop) jet at this point. Such planes are not cheap, but they do exist and it's not as though the airline wants you to have specifically piston experience because the airline only owns jets anyway.
  - iamtheworstdev 5y ago
    You can rent a small prop plane like a C152 for less than $100 an hour in the US in some places. I would be surprised if there's a turbine out there that can be rented for less than $1000.
  - frosted-flakes 5y ago
    There are plenty of commercial passenger prop planes flying today. For example, Billy Bishop Airport (YTZ) on Toronto Island only permits prop planes because of the close proximity of the airport to the city, and nearly 3 million passengers pass through YTZ each year, mostly with Porter, a regional airline.
    - tialaramex 5y ago
      Maybe this isn't obvious to frosted-flakes, or to some other readers: The propeller on a prop plane can be attached to either a piston or a jet engine. (Or mostly in smaller or experimental planes, an electric motor) So, in the example of Porter, those are Dash-8s and that's a jet engine. Yes it has the propellers on the front like those old-timey aeroplanes you saw in black and white, but you'll notice that the propellers are on the front of a jet engine. See, the engine needs spinning blades inside it to work, compressing air to run the engine, but you can choose whether to expend the resulting energy on producing yet more spinning motion for propellers (a turboprop engine) or to shove lots of fast air out of the back (a turbofan engine) A jet engine does not use leaded gasoline, that would be crazy. Whether it is spinning a propeller or just shoving fast moving air out the back, the jet engine runs on kerosene. This is still nasty stuff, but it does not have lead in it.
      - frosted-flakes 5y ago
- jacknews 5y ago
  This problem is purely a result of the engine certification regime, leading to decades-old designs that rely on lead often being the only viable options. Just relax the certifications. It's surely less dangerous to the overall population than continuing to spew lead.
- NelsonMinar 5y ago
  The article we're discussing is about a workable substitute for 100LL and how the FAA has dragged its feet for over a decade in evaluating it.

sokoloff 5y ago

Every single pilot flying for the airlines who didn't come via the military learned to fly in piston-engined airplanes. (Where would airline pilots get to the 1500 hours required since the Colgan 3407 crash?) Without a workable substitute for 100LL, banning it is not practical.

alan-hn 5y ago
Why is lead a requirement for piston-engine aircraft? Land vehicles seem to be doing just fine without leaded fuel
- FL410 5y ago
  Because airplanes still use engine designs from 70 years ago. Your next question is: why? Same reason it takes 12 years to get a replacement fuel approved.
- bombcar 5y ago
  Piston-based aircraft are built to survive numerous failures that wouldn't be a major issue for a land-based vehicle (or a boat) - both of those just kind of sit there when the power generator fails. A plane turns into a glider at that time. Off the top of my head, they mainly use magnetos instead other forms of ignition, have dual mag setups so that one can fail and the engine will still run. And lead-based fuel lubrication is simpler than other forms. Some work is being done on diesel: https://en.wikipedia.org/wiki/Aircraft_diesel_engine#Modern_developments https://en.wikipedia.org/wiki/Aircraft_diesel_engine#Modern_... - and jets of course run off of kerosene basically. And a brand-new plane is really hard to build out cost-wise, much of the aviation fleet is very, very old.
- sokoloff 5y ago
  There's a multi-part answer. Legally (the subject that requires FAA approval) is that the type-certificate (the legal basis for certification and authority to operate) for these engines specifies the use of 100LL and the standard for 100LL is a composition-based standard, not a performance-based standard. If it doesn't have the prescribed amount of TEL, it's definitionally not 100LL, even if it would meet the performance requirement of the engine. Then, from an engineering standpoint (the subject that companies are working on in order to propose fuels to the FAA via PAFI or GAMI seeking multi-model Supplemental Type Certificate), aircraft engines are stone-age in complexity and are overwhelmingly air-cooled, fixed timing [except during starting], and operate for hours on end at 75%+ of rated power. Your auto is water-cooled, has variable timing, and typically runs at 8-15% of rated power. An aircraft engine has to run reliably with cylinder head temperatures of 460ºF or more (your car's cylinders are much more tightly controlled as a result of the water cooling). Why can't airplanes use a different engine? Airplanes are (legally) certified to use a specific engine and have had extensive flight testing to determine takeoff/landing distances, fuel consumption figures, etc. Those engines are (legally) certified to use a specific fuel [or list of fuels]. Automobile engines have a horrible track record when attempted to be converted to aviation usage. Small, normally aspirated engines are able to run on low-octane, ethanol-free pump gas. The aircraft with high-powered turbo-charged engines represent around 25% of the engines. Because of their higher utilization, those engines burn around 75% of the avgas purchased in a year. (These are the CapeAir fleet, skydive operators, etc.)
  - stoltzmann 5y ago
    >The aircraft with high-powered turbo-charged engines represent around 25% of the engines. Because of their higher utilization, those engines burn around 75% of the avgas purchased in a year. Wouldn't turbo-charged engines burn jet A-1 rather than avgas?
    - cjrp 5y ago
      Turbine engines would, but that's different from turbo-charged (piston) engines.
- rlpb 5y ago
  Certifications work on a per-aircraft-type and per-engine-type basis. Converting a single aircraft type to a different engine is possible, but every single combination would need to be tested (I think this also includes flight testing) and certified individually. This is not economic. So what remains is for the existing fleet to eventually be retired and replaced by newer aircraft that use newer engines. But most light single piston aircraft being sold today still use older engine designs that require leaded fuel! And newer aircraft are so expensive, it's more economical to keep aircraft from the seventies still going. Newer aircraft are expensive because the certification and insurance requirements are extremely expensive. For example, aircraft manufacturers get sued for accidents caused by pilot error on a regular basis, and so they need insurance for that. "Average cost of manufacturer's liability insurance for each airplane manufactured in the U.S. had risen from approximately $50 per plane in 1962 to $100,000 per plane in 1988, according to a report cited by the Bureau of Labor Statistics,[14] a 2,000-fold increase in 24 years." --https://en.wikipedia.org/wiki/General_Aviation_Revitalization_Act https://en.wikipedia.org/wiki/General_Aviation_Revitalizatio... So light aircraft are stuck running ancient engine designs that require leaded fuel. There is some progress. One manufacturer uses a modern engine that runs on jet fuel (basically a diesel piston engine like in some cars). But that doesn't stop new aircraft being extremely expensive, so it looks like we're still stuck with mostly an old fleet that uses lead for a long time yet.
- DebtDeflation 5y ago
  None of the above answers actually answer your question. Lead was historically used in gasoline for two reasons - 1) to increase the octane rating (a measure of knock resistance) ans 2) to lubricate the valve seats in the cylinder head. There are multiple other chemical additives that can accomplish #1 (the fuel in the article uses one of them). For #2, the solution in the automotive world starting in the 1970s was to use hardened valve seats that didn't require lead in the fuel to lubricate. The actual answer to your question is "because the FAA won't allow it".
- p_l 5y ago
  Lead isn't actually a requirement for piston-engine aircraft. It's just that most piston engines available with: 1) world-wide certification 2) world-wide base of trained mechanics 3) already widely deployed (you can't just "swap" engines on a plane design) Are piston engines whose original design happened ages ago when leaded gasoline was the cheapest fuel with necessary performance (and that includes not just octane rating, but also things like evaporation rate at given atmospheric pressure - you don't want your fuel tank to explode due to gasoline vapors). Several newer designs in Europe have been playing around with Diesel engines again, because thanks to being heavier fraction it doesn't have as much evaporation problem of gasoline, and also diesels are by design very tolerant of fuel types. Most importantly, a plane with an aviation diesel engine can just as well use non-ethanol-added diesel from car gas station, or any of the Jet-A1 compatible fuels available on airfields (pretty sure everything that isn't accidental leftover of SR-71 blackbird operation will work just fine).
  - garaetjjte 5y ago
    >also diesels are by design very tolerant of fuel types While combustion process is tolerant, modern high-pressure pumps not so much. I don't think you can run automotive engine on Jet-A without detrimental effects on lifetime of injection system (as it uses fuel as lubricant). Does these aviation diesels use some specially hardened pumps?
coryrc 5y ago
There are substitutes that work in most engines. The others can be re-engined. Continuing to spray poison should not be in the table. But plane owners are rich and have money and time to lobby.
- sokoloff 5y ago
  Most [piston] engines? Yes. Most gallons of avgas bought per year? No (or at least until G100UL has an all-model certification to replace 100LL). I posted more details in a sibling comment here. (I want nothing more than to be able to buy G100UL.)
  - coryrc 5y ago
    https://www.aopa.org/advocacy/advocacy-briefs/regulatory-brief-avgas-100ll-alternatives https://www.aopa.org/advocacy/advocacy-briefs/regulatory-bri... Notice "not poisoning children" is not on their list of requirements. No, just that it doesn't cost you any money. If I just took TEL and sprayed it over your house, I'd be arrested and have to pay tens of thousands for remediation. But do it in a plane? No problem! You don't have to fly. You choose to poison us.
- jonititan 5y ago
  Most car engines? Yes with the exception of those with ethanol mixed into them. For aircraft engines it's a definite no. Several accidents caused by putting pump gas in aircraft.
AnIdiotOnTheNet 5y ago
I'm personally getting kind of sick of "it's not practical" as an excuse for why the general population has to suffer being poisoned and having their environment destroyed. Maybe we just don't need so many pilots and planes if it is so impractical to train and fly them?
- throwaway0a5e 5y ago
  We can't solve everything all at once. We're simply not that rich. The reason leaded avgas isn't solved yet is because by itself it's a pretty small problem as far as things that are poisoning us and out planet go. Obviously we're making progress, because people still care, but it's not getting resources in the same way that clean electrical energy is because it's a much smaller problem.
tialaramex 5y ago
I wouldn't be surprised if there are some pilots who learned in a small (prop) jet at this point. Such planes are not cheap, but they do exist and it's not as though the airline wants you to have specifically piston experience because the airline only owns jets anyway.
- iamtheworstdev 5y ago
  You can rent a small prop plane like a C152 for less than $100 an hour in the US in some places. I would be surprised if there's a turbine out there that can be rented for less than $1000.
- frosted-flakes 5y ago
  There are plenty of commercial passenger prop planes flying today. For example, Billy Bishop Airport (YTZ) on Toronto Island only permits prop planes because of the close proximity of the airport to the city, and nearly 3 million passengers pass through YTZ each year, mostly with Porter, a regional airline.
  - tialaramex 5y ago
    Maybe this isn't obvious to frosted-flakes, or to some other readers: The propeller on a prop plane can be attached to either a piston or a jet engine. (Or mostly in smaller or experimental planes, an electric motor) So, in the example of Porter, those are Dash-8s and that's a jet engine. Yes it has the propellers on the front like those old-timey aeroplanes you saw in black and white, but you'll notice that the propellers are on the front of a jet engine. See, the engine needs spinning blades inside it to work, compressing air to run the engine, but you can choose whether to expend the resulting energy on producing yet more spinning motion for propellers (a turboprop engine) or to shove lots of fast air out of the back (a turbofan engine) A jet engine does not use leaded gasoline, that would be crazy. Whether it is spinning a propeller or just shoving fast moving air out the back, the jet engine runs on kerosene. This is still nasty stuff, but it does not have lead in it.
    - frosted-flakes 5y ago
jacknews 5y ago
This problem is purely a result of the engine certification regime, leading to decades-old designs that rely on lead often being the only viable options. Just relax the certifications. It's surely less dangerous to the overall population than continuing to spew lead.
NelsonMinar 5y ago
The article we're discussing is about a workable substitute for 100LL and how the FAA has dragged its feet for over a decade in evaluating it.