This seems like such a cop-out excuse. We'd rather harm potentially millions of people with toxic materials rather than inconvenience a few dozen aviation enthusiasts. Progress moves forward, if these old engines can't function in this new world they should be scrapped and replaced with something that can do the job.

And BTW, general aviation has been asking for leaded avgas to be dropped for decades now. The holdup is not the pilots or plane owners but the goddamn FAA [0].

[0] https://www.avweb.com/insider/faa-continues-to-stall-on-g100...

Do you know of any research focused on lead-related health issues from areas of popular general aviation? Or around the supply chain for leaded fuel?

There are a few studies done. Here is one carried out by the NIH around NC. [0]

In summary they are noticeably elevated but not as high as, an example, Flint Michigan. Lead blood levels do fall off precipitously after ~2km.

[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3230438/

This is really good thank you. Worthy of a follow-up submission on HN of its own since we're pretty deep into comments here.

Note that this study is specifically focused on North Carolina. I'm curious if similar research has been done in the Western US. California in particular is very popular for GA. Here's the top 10: https://generalaviationnews.com/2020/02/03/top-10-busiest-ge...

edit: Another link: Santa Clara, CA recently banned sale of leaded fuel https://grist.org/transportation/california-county-bans-toxi...

To save people the full read, here is the most relevant sentence:

> children living within 500 m, 1,000 m, or 1,500 m of an airport had average blood lead levels that were 4.4, 3.8, or 2.1% higher, respectively, than other children.

Presumably 'valve gear components' could be designed to function without reliance on a toxic lubricant. Ultimately this comes down to being cheap.

Absolutely for new equipment that would be the case. Safely retrofitting existing equipment is quite a bit more challenging, and my suspicion (without having actual numbers) is that the vast majority of the fleet that would require those retrofits is quite old. Some of the manufacturers don’t exist anymore, so having them sign off on “this retrofit kit will safely transport you in the air for thousands of hours” wouldn’t be possible.

It’s not an unsolvable problem, but it’s thorny for sure both from a safety perspective and a cost perspective. You call it “being cheap” but my gut feeling is that retrofitting existing 40-year-old kit to handle unleaded Avgas safely would be capital-E Expensive.

General aviation is expensive certainly and for a select few very wealthy individuals. I call it cheap because there is a way to solve it, but owners of small planes are choosing not to do so (and they're not compelled to do so despite the known externalities of their outdated machinery).

Maintaining a beautiful car from the days of the Cold War is also not cheap, but it can be retrofitted to pass emissions tests. If you don't, you can't legally drive it. I don't see why the same doesn't apply to aircraft.

The trick is that there’s two tiers of expensive for GA:

- People buying, say, a new SR22 for $779,000

- People buying, say, a 1976 Cessna 172 for $72,000 and splitting it with 3 friends

Having Cirrus work on, say, regular Mogas by contracting Continental to develop a new engine would be expensive but the buyers aren’t particularly price sensitive and amortized across the typical lifetime of an aviation engine design (the IO-550 in the SR22 was first delivered in 1983) likely wouldn’t hurt much.

Trying to come up with an engine swap for the O-320 in that ‘76 172 is a whole other can of worms. Who’s going to even sign off on it? The whole aircraft is 50 years old and designed and certificated for that specific engine. There’s no financial incentive for Cessna to do it, and even if they did, the cost to do the swap would likely significantly exceed the financial capacity of many owners.

I absolutely would love to see a financially viable way to get past this! The use of LL fuel in 2022 is tragic. On the other hand, killing off a big chunk of the GA industry and leaving it solely in the purview of the Wealthy and not just dedicated hobbyists… that sucks.

For context, my family has an old Piper J3 sitting in a hangar on a farm. It definitely needs an overhaul, but to get it back in the air would likely be a low 5-figure bill; retrofitting a Mogas engine onto it in such a way that it doesn’t need to be categorized as “experimental” would be… prohibitive.

Thanks for this context. I'm not a pilot but I can absolutely relate to the joy such a machine could give.

I'd like to ask one thing further: Do you think the existence of these older cheaper planes is holding back the development of upstart companies aiming for a price point that's closer to the Cessna 172 than the SR22? If leaded fuel engines were banned by the FAA today, would that create an opportunity for new entries, maybe with EV/hybrid engines? Or are there fundamentally different manufacturing economics to safely put something like that up in the air at that price point today?

There are already alternative engines in wide use (particularly on ultralights and light-sport aircraft) that can run on regular, unleaded gasoline, like the Rotax 912[0]. The issue, as others have pointed out, is getting these newer engines certified for use on existing, older planes. This would require extensive testing to get a Supplemental Type Certificate (“STC”) to allow the engine to be installed on a certified aircraft (think anything manufactured, like a Cessna 172 or Piper Cub.)

0 - https://en.wikipedia.org/wiki/Rotax_912

I wonder if this extensive testing could be funded by a tax on leaded fuel. Seems like this would benefit everyone.

Sure, or the FAA could just go ahead and approve G100UL[0] and save everyone the trouble of an engine swap.

0 - https://www.avweb.com/insider/faa-continues-to-stall-on-g100...

Except the people who have to pay for an engine swap.

> Do you think the existence of these older cheaper planes is holding back the development of upstart companies aiming for a price point that's closer to the Cessna 172 than the SR22?

Things in aviation are incredibly expensive because of how much it costs to have things certified by the FAA for safety and reliability. I'm no legal expert but I don't think an upstart company has much wiggle room to get around that if they want to legally sell their aircraft in the US. As an example Cessna 172s are still made and AFAIK the modern ones haven't required leaded fuel for some time. A 172 is just about the most basic small airplane you can get but today a new one costs as much as a house, about $400k.

I mean, there's being cheap and then there's getting a new aviation engine FAA certified. Those aren't exactly the same thing and Bob the dentist who likes to take his Cessna 172 up on weekends can't simply approve a new engine.

This is why buying a new spec Cessna 172 from the factory floor today will still come with the good old Lycoming O-360 engine, introduced in 1955.

Cessna sells ~250 172s per year, nowhere near enough to justify new engine approval.

I'm no expert, but I'll express a wish: that modern supply constraints mean Lycoming O-360 engines may be noncompetitive to an engine design conceived today. Perhaps these old engines are suppressing the investment into an invention that turns a 250 person market into a 25,000 one?

> a select few very wealthy individuals

Whenever I see comments like this I always remember the airplane owner (Cessna 152) I used to know who drove a beat up old Toyota Corolla with the bumper sticker "My Other Car is an Airplane."