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Comment by bushbaba | Hacker News Reader

To me, this is yet another case for reducing the number of large federal governing bodies. Shouldn't the fuel approved for use be a state (or local airport) decision in all but federal military airfields?

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It would be an overall nightmare if aviation was regulated state-by-state.

I’m generally in favor of “as local as practical”, but I think that the FAA, FCC, CDC, EPA, and a few others are cases where “as local as practical” ends up being federal.

The better question is, if this an obvious improvement over the current solutions, then what is it specifically that prevents this governing body from allowing the change? And, wouldn't that same issue be a worse problem for a smaller and less well funded governing body?

While I believe G100UL is an improvement over 100LL in every important dimension except cost (where the delta is small enough to be accepted) and a small density penalty (a gallon is 5% heavier than 100LL, but contains slightly more energy as an offsetting factor, but “full tanks” will now be heavier and if the fuel has been mixed, it’ll be heavier by an unknown amount), it still needs an amount of test cell and flight testing to demonstrate that it’s equal or better.

Right now, the law says “these airplanes are allowed to use these engines”, “these engines are allowed to use 100LL”, and “100LL has the following composition”. To be legal, you need paperwork that breaks one or more of those constraints, which is what GAMI is in the process of pursuing. To get that paperwork, they have to demonstrate functional equivalence and convince the FAA to issue a supplemental type certificate (the legal paperwork that would alter the second condition above). It’s not unreasonable for the FAA to need proof. Whether they need more proof than they have is self-evidently a point of disagreement between GAMI and their supporters (I count myself among this set) and the FAA.

Even the least cynical among us understands that a government agency is not just going to abolish itself, even if it were for the best, right?

So what happens if you takeoff in state A with fuel requirement X and land in state B with fuel requirement Y?

Different states have different requirements for gasoline and that seems to work just fine. Gas in California has higher ethanol content than most states. Oregon requires that someone else pump your gas. All the states have different taxes on gasoline. Yet you can gas up in one state and drive to another without issue.

Because cars have been designed to deal with it since the 80s at least. Airplanes not so. Sure, we could begin to manufacture airplanes with more tolerance for different gasolines (and in fact we have; many modern high compression aircraft engines can take unleaded car gas), but it's taken decades to get to even this point.

What engines really don't like is constantly switching between leaded and unleaded fuel. Deciding that on a per-state basis would mean you'd need a California plane that only operates in California, and another Nevada plane for Nevada. Crossing the state line would become dangerous. Cross-country GA would quickly die that way.

Or...if California banned leaded aviation fuel. All airports wanting to service CA airplanes would need to offer unleaded aviation fuel. Thus accelerating the change quickly with market forces.

Somehow cross country travel works without issue. Not sure how that is so different from a state "FAA" type agency.

Cars - when the switch came from leaded to unleaded fuel - were more robust machines by an order of magnitude, and engine failure in cars means you have to call a garage. Engine failure in a plane means you are likely dead.

I'm all for market forces - where they make sense. In aviation, oversight saves lives.

This might be true in the short-term but unfortunately all the oversight means that a huge proportion of GA aircraft are still running carbureted engines with manual mixture control.

Modern car engines are generally much more reliable than cars made 40+ years ago. It's quite possible that this oversight is actually costing lives by limiting innovation.

Outside of hobbyist circles (may their brains match their guts), car engines in planes have a rocky history.

There was a big push in the 1990s to put "modern car engines" into GA planes, mostly diesel. It ... didn't go well. Turns out these car-derived engines were a lot less reliable than the good old Lycoming IO series, and much more expensive to maintain due to higher complexity (not to mention heavier, which always is a concern with airframes). And then there was the question on how long the manufacturer would provide replacement parts...

There is a push to make car engines happen with some EU-based manufacturers, most notably Diamond Aircraft, today. We'll see how that works.

Add that to the fact that new aircraft are prohibitively expensive, and we'll see manual mixture control-based engines for decades to come.

Not in the slightest. Aviation gasoline is heavily regulated because it has to work flawlessly in every (piston) aircraft engine. 100LL exists because it has an extremely low knock rate; any new regulation needs to maintain that. This is a safety issue, not a political one.

This is a political issue. GAMI has gone miles above and beyond what they need to do to show that their fuel works.

But regional/local fuel regulation is patently insane. That's what OP was talking about.

Why is this insane? Seems to work for cars, building code, and many other areas without any issue.

Air travel sure seems a lot like interstate commerce - will planes need different fuel at each state border? Plus, I'd rather have the professionals at the FAA rather than whoever works in each state government.

Absolutely not. Fuel approval is an engineering matter, not a political one.

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