Why do we still use leaded petrol in small airplanes

[MattA7]

leaded petrol is now banned in every country in the world for road vehicles with Algeria being the last to quit using it in 2021 because of the health/environmental damage it does however almost worldwide it’s still widely used in aviation.

The most common avgas 100LL is the equivalent to the old 5 star petrol formerly used in the UK so contains a significant amount of TEL (Tetraethyl lead) and the original avgas 100 has even higher amount.

Is there a reason behind the continuing use of small piston aircraft still being manufactured with leaded petrol engines or is it simply a lack of desire to switch to unleaded.

 

[Bletchleyite]

Because most of them are ancient, perhaps?

Also because lead was a local pollution issue, if you're spending much time breathing in pollution from planes then there's something a bit odd going on, and if you're concerned about birds we should ban planes.

 

[Ediswan]

leaded petrol is now banned in every country in the world for road vehicles with Algeria being the last to quit using it in 2021 because of the health/environmental damage it does however almost worldwide it’s still widely used in aviation.

The most common avgas 100LL is the equivalent to the old 5 star petrol formerly used in the UK so contains a significant amount of TEL (Tetraethyl lead) and the original avgas 100 has even higher amount.

Is there a reason behind the continuing use of small piston aircraft still being manufactured with leaded petrol engines or is it simply a lack of desire to switch to unleaded.

There is recent news on this: https://www.aopa.org/news-and-media/all-news/2022/september/01/closer-to-an-unleaded-future

The FAA signed on September 1 supplemental type certificates that allow General Aviation Modifications Inc.’s 100-octane unleaded fuel (G100UL) to be used in every general aviation spark-ignition engine and every airframe powered by those engines. The move was hailed by the industry as a major step in the transition to an unleaded GA future.

 

[birchesgreen]

Because most of them are ancient, perhaps?

Also because lead was a local pollution issue, if you're spending much time breathing in pollution from planes then there's something a bit odd going on, and if you're concerned about birds we should ban planes.

Mind you most cars switched quite easily to unleaded, i suspect its more a case of being something obscure enough to slip under the radar (so to speak, not literally like Mattias Rust's Cessna) until now.

 

[70014IronDuke]

Because most of them are ancient, perhaps?

I doubt that.
I suspect it's because of the original reason for adding lead to fuels - namely to increase the compression ratio in the engine to get more oooomph from the smallest (and lightest) motor you dare fit to get the performance you want from the aircraft.

 

[edwin_m]

I doubt that.
I suspect it's because of the original reason for adding lead to fuels - namely to increase the compression ratio in the engine to get more oooomph from the smallest (and lightest) motor you dare fit to get the performance you want from the aircraft.

But per post #3 that's been solved now. Have any new aviation piston engine designs in the last couple of decades been able to use standard automotive unleaded?

The original impetus for unleaded petrol was because catalytic converters were needed to reduce local pollutants from cars, and the lead poisoned the catalyst. Planes have never had catalytic converters, and this may be part of the reason for their exemption.

 

[70014IronDuke]

But per post #3 that's been solved now. Have any new aviation piston engine designs in the last couple of decades been able to use standard automotive unleaded?

I''d better read it then! <slaps wrist>.

I am told Rotex (Rotax?) engines use standard automotive fuels - so I presume unleaded. Or at least some of their designs. I claim no direct knowledge - just talking with super-light aircraft designers.

 

[Ediswan]

Mind you most cars switched quite easily to unleaded, i suspect its more a case of being something obscure enough to slip under the radar (so to speak, not literally like Mattias Rust's Cessna) until now.

As per the link in post #3, it has definitely not been obscure in the US, especially so in California. Has received little mention in the UK as the UK general aviation market is small.

GAMI cofounder George Braly said, “This is a big day for the industry. It means that for a lot of our general aviation communities, and especially for a high fraction on the West Coast, relief is on the way. And it means that our industry will be able to go into the future and prosper, and provide the essential infrastructure for this country for everything from Angel Flights to critical training of our future airline pilots.”