Will 100LL really stop in 2029/2030?

172andyou said:
I mean, I guess that's fine for XC. But you really want something supersonic for intercontinental service. Concorde was way faster. Not even in the same ballpark.
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Sure, I suppose that's okay for intercontinental service if you're a poor. The International Space Station does 14,900kts across the ground, with no engine, no fuel stops, and doesn't care about wind. Way faster than Concorde. Not even in the same ballpark.
 
StraightnLevel said:
At 143 kts? Seriously?

Compare to Bonanza, SR22/22T, M-350, and Cessna twins. Not even in the same ballpark.
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StraightnLevel said:
At 143 kts? Seriously?

Compare to Bonanza, SR22/22T, M-350, and Cessna twins. Not even in the same ballpark.
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If you go to FlightAware's Flight Tracking by Type at a time where it's daylight over all of the USA, I think you'll found the most common GA non-trainer is the Cessna Skylane, and you'll also if you sum both versions of the SR22 it is approximately the same as the number of Skylanes. Bonanzas usually are half as numerous as Cirruses, and the number of owner flown twins are significantly less numerous than Bonazas.

You may not think of a Skylane as being a traveling machine, but it appears that their owners don't agree.
 
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wanttaja said:
As of 1 January 2026, the FAA active registry contained:

Cessna 172: 21,352
Cessna 182: 13,929
Cirrus SR models: 8,301
SR-20: 1,509
SR-22: 6,788
Bonanza (models 33, 35, and 36): 10,363

Ron Wanttaja
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I would be more curious about annual hours flown.

Tim
 
tspear said:
I would be more curious about annual hours flown.
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Harder to get reliable data on that. The FAA General Aviation Survey only issues annual hour estimates on broad aircraft classes, such as two-seat reciprocating, four-to-six-seat reciprocating, etc.

I have a system for estimating hours using the accident database...computing the age of each aircraft, comparing it to the number of hours the NTSB report states. I call this the Ron's Really Stupid System, though I admit for homebuilts, it seems logical (e.g., Fly Babies flying a lot less than RV-10s).

Anyway, I ran the RRSS on my database of ~5500 production-aircraft accidents. Here's what I get:

Cessna 172: 286 hours per year, 3100 accidents.
Cessna 150/152: 215 hours per year, 805 accidents
Cessna 210: 132 hours per year, 703 accidents
Cirrus SR-20/22: 254 hours per year, 231 accidents (57 SR20s, 174 SR22s)
Bonanza 36: 185 hours, 305 accidents
Piper PA-28: 128 hours, 556 accidents (PA-28-140 through PA-28-181)

[Edit: I should mention here that the number of accidents listed is over a different time period for each type of aircraft. This particular database was assembled from separate ones for each aircraft, with the primary reason to compare accident causes, not accident rates.]

Didn't include Cessna 182s in my database, so can't give the answer there.

The 172 is used a *lot* as a trainer, so that might explain the higher hours.

Note that this is way approximate method which may not have any relationship with reality....

Ron "Not called RRSS for no reason" Wanttaja
 
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wanttaja said:
Harder to get reliable data on that. The FAA General Aviation Survey only issues annual hour estimates on broad aircraft classes, such as two-seat reciprocating, four-to-six-seat reciprocating, etc.

I have a system for estimating hours using the accident database...computing the age of each aircraft, comparing it to the number of hours the NTSB report states. I call this the Ron's Really Stupid System, though I admit for homebuilts, it seems logical (e.g., Fly Babies flying a lot less than RV-10s).

Anyway, I ran the RRSS on my database of ~5500 production-aircraft accidents. Here's what I get:

Cessna 172: 286 hours per year, 3100 accidents.
Cessna 150/152: 215 hours per year, 805 accidents
Cessna 210: 132 hours per year, 703 accidents
Cirrus SR-20/22: 254 hours per year, 231 accidents (57 SR20s, 174 SR22s)
Bonanza 36: 185 hours, 305 accidents
Piper PA-28: 128 hours, 556 accidents (PA-28-140 through PA-28-181)

Didn't include Cessna 182s in my database, so can't give the answer there.

The 172 is used a *lot* as a trainer, so that might explain the higher hours.

Note that this is way approximate method which may not have any relationship with reality....

Ron "Not called RRSS for no reason" Wanttaja
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Ron,

I recall discussing hours flown with a Cirrus rep a few years ago. According to him, Cirrus was seeing an average close to 500 hours a year for the first five years, then declining to roughly 250 a year until ten years old, and 100 hours a year after ten years. Since all hearsay, take it with a grain of salt. But it does match anecdotal knowledge.

Tim
 
172andyou said:
I mean, I guess that's fine for XC. But you really want something supersonic for intercontinental service. Concorde was way faster. Not even in the same ballpark.
Click to expand...

wanttaja said:
Harder to get reliable data on that. The FAA General Aviation Survey only issues annual hour estimates on broad aircraft classes, such as two-seat reciprocating, four-to-six-seat reciprocating, etc.

I have a system for estimating hours using the accident database...computing the age of each aircraft, comparing it to the number of hours the NTSB report states. I call this the Ron's Really Stupid System, though I admit for homebuilts, it seems logical (e.g., Fly Babies flying a lot less than RV-10s).

Anyway, I ran the RRSS on my database of ~5500 production-aircraft accidents. Here's what I get:

Cessna 172: 286 hours per year, 3100 accidents.
Cessna 150/152: 215 hours per year, 805 accidents
Cessna 210: 132 hours per year, 703 accidents
Cirrus SR-20/22: 254 hours per year, 231 accidents (57 SR20s, 174 SR22s)
Bonanza 36: 185 hours, 305 accidents
Piper PA-28: 128 hours, 556 accidents (PA-28-140 through PA-28-181)

Didn't include Cessna 182s in my database, so can't give the answer there.

The 172 is used a *lot* as a trainer, so that might explain the higher hours.

Note that this is way approximate method which may not have any relationship with reality....

Ron "Not called RRSS for no reason" Wanttaja
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Love this "rough cut" of your database.

What jumps out at me is the incident rate - 172, 152, 21, and PA-28 seem to be accident prone from this view......
 
StraightnLevel said:
Love this "rough cut" of your database.

What jumps out at me is the incident rate - 172, 152, 21, and PA-28 seem to be accident prone from this view......
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Of course, the 172, 15X series, and the PA-28s are the most common aircraft in the fleet, so they'll naturally have more accidents.

Also, my production-aircraft database was put together to do rough comparison of accident causes; it's a hodgepodge of separate databases I put together in the past. It thus doesn't run from Year X to Year Y for all aircraft; the number of years (and the stop and end year) varies with aircraft types. Doesn't make a difference when you're looking at causes, but might give the impression that one aircraft has more or less than average when the only reason was a greater or fewer number of hours.

I'll edit my previous post to reflect that.

My most extensive production-aircraft database is that covering the 172, since I use that to compare accident rates with homebuilt aircraft. I look at the "Average Fleet Accident Rate"; the average number of accidents affecting that aircraft type in a given year. The Fleet Rate doesn't take flight hours into account.

Working from memory, the Average Fleet Accident Rate for overall homebuilts was 0.75%, while the rate for Cessna 172s was 0.60%. The RV-7 comes out at about half that.

Yet...this does not take into account the flight time flown by each type. The FAA General Aviation Survey says that four-seat reciprocating aircraft fly about 110 hours a year, while homebuilts fly 50. So this, in itself, would negate the apparent advantage of the RV-7 over the 172. If one goes by the data I posted above, it's even worse.

The problem here is equivalent use. Ideally, one would compare the RV-7 with 172s that are privately owned, flying for their owner's "education and recreation." Not trainers, many of which have instructors with Commercial tickets and undergo a more-strict maintenance schedule. No such data exists. The same FAA survey that estimates the annual hours also says the average four-to-six seat reciprocating-engine aircraft does the majority of its flying for commercial or professional purposes... vs. less than 10% for the homebuilts.

So anyway, some cautions about the data.....

Ron Wanttaja
 
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Seventy pages of the same information that has been published in the past. We have pillars and tranches, and we're leveraging our experience for a deep dive into acronym creation.
I'm reminded of the Digital Buzz Phrase Generator that I laughed at in high school. Industry is doing the work, bureaucrats...mostly impede progress. Some things never change.
 
"The information contained in this document is intended to be leveraged by relevant stakeholders..."

Uh-huh.

It's going to be great, but if it's not:

"Aircraft and engine modifications may go beyond using the fuel itself and may be motivated by other factors such as increased efficiency, the ability to utilize lower octane fuels, or to lower maintenance. Some examples include changes to ignition timing and replacement of certain materials within the fuel system. The TC/STC process can also be used to install anti-detonation injection systems, electronic ignition systems, or even to replace a spark-ignition piston engine with a compression-ignition engine..."​

So, we'll have this great new UL fuel, but if you can't use it you can always install a diesel engine. :dunno:
 
When I read that, it confirmed just how out of touch with reality they are.
Just swap engines. How hard can it be?
 
Phillips 66 told the FAA it was not possible back in 2024 when they dropped out of the effort.
The gears grind slowly.
 
I wasn't able to go to the VP/Lyondell talk at Osh but this is what was said per an AOPA article:

"Mark Walls, VP Racing’s director of research and development, said that some high-performance or turbocharged engines will need minor timing adjustments to maintain safety margins, but that those changes will not affect engine performance or fuel economy.

“You're going to hear, ‘Yes, you're going to have to pull some timing out of this engine or that engine,’ and the main concern is, ‘Oh, we're going to lose a lot of power or we're going to lose fuel economy.’ The data's not showing that. The data's showing that there's really no negative effects on power and fuel economy across these engines,” said Walls."
 
I have a question about the prospect of changing timing to accommodate the new fuel:

In my experience (as limited as it is) even small changes in timing made fairly large differences in power, smoothness and mostly ease of startup (especially hot start). But all of my experience with changing timing is in aircraft engines using the same fuel (100ll). Could there be something about these new unleaded 100 octane fuels that makes up for the timing change so that the total effect of (for instance) 3 degrees isn't such a big deal?

I'm just throwing spitballs here because I have no better ammunition.
 
NealRomeoGolf said:
I wasn't able to go to the VP/Lyondell talk at Osh but this is what was said per an AOPA article:

"Mark Walls, VP Racing’s director of research and development, said that some high-performance or turbocharged engines will need minor timing adjustments to maintain safety margins, but that those changes will not affect engine performance or fuel economy.

“You're going to hear, ‘Yes, you're going to have to pull some timing out of this engine or that engine,’ and the main concern is, ‘Oh, we're going to lose a lot of power or we're going to lose fuel economy.’ The data's not showing that. The data's showing that there's really no negative effects on power and fuel economy across these engines,” said Walls."
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I suspect Mr. Walls is saying performance won't be affected when using the different timing with VP 100R, but he's not addressing how performance might change with 100LL and the new timing. Transition to an UL fuel won't be quick; we'll be going back and forth, and running mixtures of UL and 100LL for years.
 
Half Fast said:
I suspect Mr. Walls is saying performance won't be affected when using the different timing with VP 100R, but he's not addressing how performance might change with 100LL and the new timing. Transition to an UL fuel won't be quick; we'll be going back and forth, and running mixtures of UL and 100LL for years.
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What makes you think that? There is less than an effective three year window. And FBOs are not going to be wanting to left holding 100LL when 12/31/2030 hits and they can no longer legally sell it. So once there is any market accepted solution, expect most FBOs to start switching. There will likely be very little overlap, maybe a year at most.

Tim
 
tspear said:
What makes you think that? There is less than an effective three year window. And FBOs are not going to be wanting to left holding 100LL when 12/31/2030 hits and they can no longer legally sell it. So once there is any market accepted solution, expect most FBOs to start switching. There will likely be very little overlap, maybe a year at most.

Tim
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What makes me think that is that it's only 2026 and the FAA is already saying they will need to extend the 2030 deadline (that assumes someone will make TEL, of course). Even if they don't get the extension, we'll probably see more and more FBOs selling an UL fuel over the next couple of years while others continue with 100LL. The FAA, like much of the USG, tends to move at the speed of a turtle chasing a snail across a field of peanut butter, and the FAA still has a bunch of work to do, so I suspect a transition will take a while.

Even if you're correct, a year is still significant. Your timing is adjusted for 100R, let's say, but your tank is 1/4 100R and 3/4 100LL. What's your performance? Worse yet, suppose it's 1/4 100R, 1/4 Swift UL100, 1/4 G100UL, and 1/4 100LL. Maybe enough paint and o-rings will fall off so that the weight reduction will give you back full performance.....
 
Half Fast said:
t he's not addressing how performance might change with 100LL and the new timing. Transition to an UL fuel won't be quick; we'll be going back and forth, and running mixtures of UL and 100LL for years.
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This, precisely.

G100UL appears to not have this caveat.

Pick your poison.....or just buy a turboprop.
 
tspear said:
What makes you think that? There is less than an effective three year window. And FBOs are not going to be wanting to left holding 100LL when 12/31/2030 hits and they can no longer legally sell it. So once there is any market accepted solution, expect most FBOs to start switching. There will likely be very little overlap, maybe a year at most.

Tim
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The only question would be if production can ramp up fast enough. Since they're just swapping tel for etbe, it seems like that could be done almost overnight. The issue will be getting all the airplanes modified. There might be some rural airports that are sitting on tanks of 100ll for a couple months, but all the ones that move fuel will be switched over within a few weeks.
 
StraightnLevel said:
This, precisely.

G100UL appears to not have this caveat.

Pick your poison.....or just buy a turboprop.
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If most planes can burn mogas, I hope that most FBOs will offer it, independent of the complexities related to 100LL replacement.
 
MountainDude said:
If most planes can burn mogas, I hope that most FBOs will offer it, independent of the complexities related to 100LL replacement.
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"Most planes" isn't the goal, nor should it be.

Most planes don't fly enough hours or burn enough fuel to drive the decision. Note the data posted above, and look at the average hours for the high-performance engines.

Auto fuel won't solve the problem, and FBOs aren't going to install a whole new set of tanks to sell fuel for a small portion of the fleet that doesn't buy very much fuel in the first place.
 
i'm not understanding, the faa puts out a document basically acknowledging the reality of the situation and stating they've heard all our arguments, everyone is still unsatisfied... wth. would it be better if they just released the fuels and let what may be may?
 
Reading this thread has been like binge watching a uboob of the 5 stages of Coping in 1.5x. To quote that clownshoe PBD: I am "valuetained".


737steve said:
Phillips 66 told the FAA it was not possible back in 2024 when they dropped out of the effort.
The gears grind slowly.
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No, they dropped out because their specific manganese brew retk'd the test stand lawnmower. That doesn't mean it isn't possible. To wit, Gami proved it's possible...with paint thinner.
:biggrin:
 
MackMooney said:
i'm not understanding, the faa puts out a document basically acknowledging the reality of the situation and stating they've heard all our arguments, everyone is still unsatisfied... wth. would it be better if they just released the fuels and let what may be may?
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The FAA is run by idiots. If you have to be ordered to make a road map and can't come up with that idea yourself, you need to go back to leadership school.
 
NealRomeoGolf said:
I wasn't able to go to the VP/Lyondell talk at Osh but this is what was said per an AOPA article:

"Mark Walls, VP Racing’s director of research and development, said that some high-performance or turbocharged engines will need minor timing adjustments to maintain safety margins, but that those changes will not affect engine performance or fuel economy.

“You're going to hear, ‘Yes, you're going to have to pull some timing out of this engine or that engine,’ and the main concern is, ‘Oh, we're going to lose a lot of power or we're going to lose fuel economy.’ The data's not showing that. The data's showing that there's really no negative effects on power and fuel economy across these engines,” said Walls."
Click to expand...
Their is however an egt increase when you retard the timing. Which could matter on turbo charged engines. That increase was shown on their own data.
 
StraightnLevel said:
"Most planes" isn't the goal, nor should it be.

Most planes don't fly enough hours or burn enough fuel to drive the decision. Note the data posted above, and look at the average hours for the high-performance engines.

Auto fuel won't solve the problem, and FBOs aren't going to install a whole new set of tanks to sell fuel for a small portion of the fleet that doesn't buy very much fuel in the first place.
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I have not seen good data that supports your statement "a small portion of the fleet that doesn't buy very much fuel".
If most 172s and 182s can burn mogas, that is already most of the fleet. And they fly a lot.
 
So I had a really good discussion with Claude about the fuel burn number. It pulled the data from the '24 FAA Survey....a couple interesting things:

- as we know, the piston twin freight dog is extinct. All piston twins account for 10% of hours flown
- personal+business use hours are about equal to training hours.

Most business travel will be HP. "Personal" is probably about an even spilt because you have to account for club planes doing local burger runs (a lot) as well as guys like me flying across the country (fewer, but more hours). Most training, but not all, will be engines that could use 94 octane.

The guess we came up with was about 50% of the fuel burned could be displaced by 94ul/mogas.

One wrinkle: remember a year or so ago when UND went to 94UL in their trainer fleet and started getting major valve recession? I know some people burn mogas successfully, but even planes that are supposed to be capable can have issues. I suspect it has a lot to do with "conscientious owner" vs "full rental power".
 
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So, the Assistant Deputy FAA whatnot who just pronounced that the 2030 deadline will slip is leaving the FAA. I wonder what the next version of "this is the final word" pronouncement will be made by his successor?
 
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