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mr_toadtoday at 6:10 PM1 replyview on HN

Only in piston engines, which are a minority of propeller planes. Most commercial propeller aircraft are turboprops, and they use jet fuel. And diesel engines are slowly taking over from gasoline in piston engines.


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mh-today at 6:26 PM

Correct. For others reading this though: virtually all piston-engine GA aircraft in the US today are still burning 100LL (leaded), and there are nearly 200,000 of them actively flying.

There is a timeline to transition to UL, but very low collective confidence it'll happen by the 2030 goal.

edit: to the commenter that fired off the reactionary reply and deleted it before I could help you. No, not because "[rich people] won't do the right thing." It's because lead is an anti-knock additive for piston engines, and a safe replacement has to go through unimaginable amounts of testing. Once it's certified, one must still figure out scaling production, distribution, etc. Aviation is a very slow moving industry and regulatory environment, which I'm personally thankful for.

PDF (77pgs): https://download.aopa.org/advocacy/2026/2026-01_Draft-Unlead...

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