Without a workable substitute for 100LL, banning it is not practical.
(I want nothing more than to be able to buy G100UL.)
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.
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_... - 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.
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.)
Wouldn't turbo-charged engines burn jet A-1 rather than avgas?
(Note that what aviation considers high-compression is laughably low-compression in modern automobiles.)
(For airplanes vs. car engines, probably other effects are more significant, like higher head temps, poorer mixture due to carburetors, fixed ignition and whatnot.)
An IO-550 is a very common 6-cylinder aircraft engine. 550 cubic inches (just over 9 liters) of displacement from 6 cylinders (5.25” bore x 4.25” stroke, redline typically 2700 RPM).
This is one of the reasons why I think almost all of the innovation in GA, including modern powerplants, electronic ignitions, advanced avionics electronic systems, and even safety systems, is happening in the Experimental category, not in certified factory-built airplanes. If I owned a Cessna and decided to so much as run a USB charger out to the panel, the FAA would come down on me like a ton of bricks. But I could replace the engine monitor or autopilot on my E/AB category airplane, and the FAA doesn't even care. Hell, I could replace the entire engine with something I invented in my basement, and all I have to do is re-do Phase I testing.
(BTW, your USB charger example is a minor modification, able to signed off by an A&P.)
The FAA says no such thing. There are modern FADEC piston engines:
* https://www.lycoming.com/engines
* https://en.wikipedia.org/wiki/Austro_Engine_E4
and you can new planes with them:
* https://www.flyingmag.com/we-fly-diamond-da40-ng/
It's just there are (over) 100K pre-FADEC planes out there with perfectly fine "stone-age" engines, and few people want to spend US$ 40K on a new engine when they can overhaul their current one for half the price when the time comes.
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_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.
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)
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).
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?
I would be surprised if there's a turbine out there that can be rented for less than $1000.
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.
To be even more technical, the difference between turbine and piston engines is in the combustion chamber: open combustion in the case of a turbine and closed in the case of a piston.
Finally, there are turbine engines that run just fine on LL100 (leaded avgas). Garrets, for example. One can even mix gas and jet-A in those. It is not recommended to run avgas for more than 1000 hours though due to potential issues with lead deposits. Some military jets engines are designed to run on almost anything combustible except maybe coal dust (I am exaggerating somewhat, of course).
Just relax the certifications. It's surely less dangerous to the overall population than continuing to spew lead.
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.