Drop-in 100LL Replacement "Impossible"?

[mondtster]

They should have spent another dollar and designed a proper experiment. Off my snarky soap box now…..

Perhaps it is a better experiment than you think. Bladders have been made from various materials over the years, some of which have held up better than others. People aren’t going to be happy if their 60+ year old bladders suddenly won’t hold the new fuel.

 

[WDD]

That was Swift 94UL that was tested at UND. The "test" was not well run from a scientific perspective. No control group, no baseline data. It was suspended when there was some valve recision.
It was not 100UL and I'm pretty sure GAMI demonstrated the valve issue UND had would not have happened with 100UL.

Ah - my bad. Appreciate the correction.

 

[WDD]

Perhaps it is a better experiment than you think. Bladders have been made from various materials over the years, some of which have held up better than others. People aren’t going to be happy if their 60+ year old bladders suddenly won’t hold the new fuel.

Yes - a test to show that old planes would work well with 100UL would be good. But that wasn’t a good test design.

 

[robin ardoin]

Perhaps it is a better experiment than you think. Bladders have been made from various materials over the years, some of which have held up better than others. People aren’t going to be happy if their 60+ year old bladders suddenly won’t hold the new fuel.

Hmmm Put it in 60 year old bladders then blame the fuel when the bladder fails. I understand your point but, in the example you suggest, when inevitably the bladder fails, one would not know if it would not have failed at the same time in service had 100LL continued to be used. It would be hard to normalize aged bladders for controlled testing. Even a bladder in one wing could have issues unrelated to fuel that the identical bladder in the other wing did not encounter. GAMI has done the best controlled testing in the lab using material samples. In the field with old bladders, truly controlled testing is not possible.

 

[Checkout_my_Six]

Hmmm Put it in 60 year old bladders then blame the fuel when the bladder fails. I understand your point but, in the example you suggest, when inevitably the bladder fails, one would not know if it would not have failed at the same time in service had 100LL continued to be used. It would be hard to normalize aged bladders for controlled testing. Even a bladder in one wing could have issues unrelated to fuel that the identical bladder in the other wing did not encounter. GAMI has done the best controlled testing in the lab using material samples. In the field with old bladders, truly controlled testing is not possible.

Why didn't the other 60 yo bladder with the 100LL fail.....?

 

[Capt. Geoffrey Thorpe]

Why didn't the other 60 yo bladder with the 100LL fail.....?

Why did only one of the whole bunch of year old bladders that were both run on 100LL fail?

Thick black sticky residue under my wing.

When I was pre-flighting my plane I noticed I had overfilled my fuel tanks and had some blue dye on my landing gear which is typical when I put too much fuel in however when I was looking down there I noticed significant streaks of black mixed in with the blue. The only way to describe it is...

www.pilotsofamerica.com

 

[robin ardoin]

Why didn't the other 60 yo bladder with the 100LL fail.....?

Prove cause and effect. My point is, it may have been from components of G100UL, it may have been that the time was up. The AOPA Baron issue was likely overfill spillage leaking around the bladder causing dissolution of the tape adhesive...common with 100LL also. Again, this is why a true controlled trial in the field is hard to accomplish. We will only know when very large numbers of aircraft are using G100UL.

 

[Checkout_my_Six]

Over fill will not cause that.....

 

[mondtster]

Yes - a test to show that old planes would work well with 100UL would be good. But that wasn’t a good test design.

Depends on what was being tested. I have my doubts that bladders were the focus.

 

[robin ardoin]

Over fill will not cause that.....

If it leaks around the exterior of the bladder it will.

 

[William Pete Hodges]

As George says, "it's about DATA"... something that GAMI has... and apparently of which the other parties had/have very little. Could it be that GAMI has the most capable aviation piston engine test stand in the country/world?

I believe they do. I took their advanced pilot course and have read articles and seen interviews about the test stand, it's capabilities, and what they learned about engine operating characteristics. The information they learned contributed directly to the building of GAMI injectors and other products as well as the creation of G100UL avgas. It is all fascinating stuff. What they have accomplished is nothing short of amazing. We owe them our thanks and support.

 

[Half Fast]

Depends on what was being tested. I have my doubts that bladders were the focus.

I assume that in order to get the fleet-wide airplane STC, GAMI had to show compatibility with fuel tanks, bladders, pumps, hoses, seals, etc., etc. I'm curious whether they also had to show compatibility with repair materials, adhesives, oil additives like CamGuard, and so forth, things that aren't part of the original type certificate.

Maybe @Martin Pauly knows more?

 

[Bell206]

I assume that in order to get the fleet-wide airplane STC, GAMI had to show compatibility with fuel tanks, bladders, pumps, hoses, seals, etc., etc. I

All STC holders are required to show their alteration is compatible with the original TC they are "supplementing." If it doesn't and they are acceptable to the FAA, those differences will be listed in the STC Conditions and Limitations section.

I'm curious whether they also had to show compatibility with repair materials, adhesives, oil additives like CamGuard, and so forth, things that aren't part of the original type certificate.

Most approved STC documentation will have a statement similar to this: "The installer must determine whether this design change is compatible with previously approved modifications." So any compatibility requirements for items added to the aircraft outside its original TC fall to the installer of the STC and not the STC holder.

 

[Checkout_my_Six]

Depends on what was being tested. I have my doubts that bladders were the focus.

They claim that they were. They had several bladder tanks (a variety of new and old) full of fuel circulating at elevated temperatures for months....with no leaks or degradation to the materials.

 

[mondtster]

I assume that in order to get the fleet-wide airplane STC, GAMI had to show compatibility with fuel tanks, bladders, pumps, hoses, seals, etc., etc. I'm curious whether they also had to show compatibility with repair materials, adhesives, oil additives like CamGuard, and so forth, things that aren't part of the original type certificate.

Maybe @Martin Pauly knows more?

I know that some component testing like you suggested was done a while ago (prior to the STC for the fuel being issued). My response was primarily targeted at the comments suggesting that the "testing" done in the Baron wasn't worthwhile because it wasn't a properly constructed test. I have my doubts that there was really much purpose to this "test" other than to drum up publicity and prove that the fuel actually exists and that engines do run on it.

As far as I'm concerned, the STC has already been issued for the fuel so GAMI must have proven that there was at least some acceptable level of compatibility with fuel system components. But, I also wouldn't be the least bit surprised if we were to find out that whatever accelerated testing was performed to prove compatibility missed the mark and some unexpected surprises pop up once the fuel starts being used in various aircraft rather than just select test aircraft. The leak on this Baron may be an example of a surprise.

 

[tspear]

As far as I'm concerned, the STC has already been issued for the fuel so GAMI must have proven that there was at least some acceptable level of compatibility with fuel system components. But, I also wouldn't be the least bit surprised if we were to find out that whatever accelerated testing was performed to prove compatibility missed the mark and some unexpected surprises pop up once the fuel starts being used in various aircraft rather than just select test aircraft. The leak on this Baron may be an example of a surprise.

I suspect the issue is either one or a combination of the following that leads to this unexpected surprise (and I think part of the reason AOPA did the test).
1. Accelerated aging, does not perfectly match actual aging.
2. Repairs done with unapproved sealants that are incompatible.
3. Crud in the tank/bladder had "dried" and effectively became a crust which "sealed" the cracks/leaks/pin holes. G100UL actually dissolves some of this crud which previously plugged the leak. A friend had this happen to his diesel tractor when he switched from ag diesel to a bio-diesel. In that case, the tank had rusted out, and he never had bothered to repair it.

Tim

 

[Capt. Geoffrey Thorpe]

I suspect the issue is either one or a combination of the following that leads to this unexpected surprise (and I think part of the reason AOPA did the test).
1. Accelerated aging, does not perfectly match actual aging.
2. Repairs done with unapproved sealants that are incompatible.
3. Crud in the tank/bladder had "dried" and effectively became a crust which "sealed" the cracks/leaks/pin holes. G100UL actually dissolves some of this crud which previously plugged the leak. A friend had this happen to his diesel tractor when he switched from ag diesel to a bio-diesel. In that case, the tank had rusted out, and he never had bothered to repair it.

Tim

4) bladder was old, patched, and would have failed if they had kept on using 100LL just like all the other bladders that eventually fail with 100LL.

 

[PaulMillner]

a high-octane unleaded replacement for 100LL says it's impossible, according to Aviation Week. "There is no such thing as a drop-in unleaded fuel to replace 100 [LL]," Dan Pourreau...
www.avweb.com

Dan appears to be making the common mistake of confusing *inspection* criteria of a fuel with *core properties* of the fuel. The core properties are generally established in this case by full-scale testing on aircraft engines... then, a diligent engineer will identify which inspection criteria to use in the field to verify that a given fuel sample is adequate relative to the core properties. Octane test engine tests alone are not adequate to do that, since octane test engines don't accurately represent the full operating envelope of an aircraft engine. That's why avgas specifications include *other* composition controls as well.

GAMI has in fact come up with a formulation that meets or exceeds the requirements for all piston engines in the fleet. Unfortunately, Lyondell/VP-Racing and Swift Fuels have not.

Sounds like a possibly terminal case of sour grapes. Take two tankfuls of G100UL and call me in the morning.

Upton Sinclair wisely explained that it is very difficult to explain something to someone whose employment is dependent on them NOT understanding it.

G100UL doesn't quite fall within all the ASTM specifications of 100LL - I think it's slightly too dense or something like that - which is one of the reasons they aren't part of the PAFI/EAGLE program.

Actually, the 100LL ASTM specification, D910, doesn't limit fuel density. It only requires that the manufacturer report density. Most 100LL is less dense than G100UL, but on occasion, there are batches of 100LL that are as dense as G100UL. In any case, that wasn't the reason GAMI didn't join PAFI, and PAFI doesn't require candidate fuels to meet D910, the 100LL spec. The FAA foolishly tried to make that happen for 20 years, and failed... that's when they launched PAFI.

it may well be that the ASTM standards are unnecessarily restrictive.

That certainly is true, and the basis of the FAA's failed 20 year effort... but then, they only wasted a $200 million or so of the taxpayers' money, so no harm, no foul, eh?

It would have been easier and less costly (except for the piston owner) than this 50 year fuel fiasco for someone to have come up with an STC that involves a knock sensor that modifies anything (timing, fuel, rpm) if a ham fisted pilot or bad fueled engine begins to detonate. Buick figured it out for their turboed production vehicles in the 1980's. Then the need for lead would go away. Lead fouls O2 sensors, so there's that chicken & egg thing.

Now, now... the FAA's only been at it for 33 years. Patience, grasshopper! GAMI solved the problem in a year, but then it took 12 years to get the FAA to approve it, lightning speed by comparison. The problem with a knock sensor, if you can make it work with all the white noise generated by the prop, is that whatever you do to STOP the knock also reduces the engines power output... and for certification reasons, that's a non-starter... now your allowable gross weight, balked landing performance, climb rate... other safety important performance attributes, change in some undefined fashion. That requires that the airplane go through certification over again. No one has the time or funds to recertify all the aircraft in the fleet via flight testing, etc.

Big oil has been a dismal failure in developing an alternative to 100LL.

Big oil isn't very excited about avgas one way or the other, it's such a tiny product volume. And the FAA stepped in around 1991 and told the oil companies that the FAA would lead the effort. When folks tried to color outside the lines, the FAA exerted coercive force to keep folks in line... Remember, if the FAA decides your *jet fuel* isn't acceptable, that can be a huge expensive problem. And certain FAA folks reportedly threatened to do just that. So although unfortunate, I can't fault big oil too much for not pointing out to the FAA that the emperor has no clothes. OTOH, there are those in big oil who want to ride the lead donkey as LONG as possible... as long as there's lead, this small volume but high margin product is protected from new market entrants. If you make avgas without lead, all kinds of folks might get in on the act, and compete away those tasty margins.

making noise that to be a commercial product and protect against liability, the fuel must meet an {ASTM} spec.

Regulators, lawyers, and insurance companies don't think so. Those spreading FUD (fear, uncertainty, and doubt) have found this refrain useful, but the facts don't support it.

Paul

 

[Racerx]

That was Swift 94UL that was tested at UND. The "test" was not well run from a scientific perspective. No control group, no baseline data. It was suspended when there was some valve recision.
It was not 100UL and I'm pretty sure GAMI demonstrated the valve issue UND had would not have happened with 100UL.

I believe erau ran the Gami gas for a bit

 

[Hang 4]

I believe erau ran the Gami gas for a bit

You're correct. Quote from an AOPA article on the state of unleaded development

Embry-Riddle Aeronautical University did a complete FAA engine durability test of GAMI’s unleaded avgas, combined with 170 hours of in-flight functionality and reliability testing as a part of the FAA certification program. Embry-Riddle found G100UL to be acceptable on all accounts.

 

[Pinecone]

Depends on what was being tested. I have my doubts that bladders were the focus.

They were. George has a Bonanza and a T-34, both with bladders.

 

[mondtster]

They were. George has a Bonanza and a T-34, both with bladders.

As was mentioned already, bladder testing was performed previously. Years ago at this point if I’m not mistaken. If this test was really a test for bladders, don’t you think it is a bit late or the STC was issued prematurely if GAMI is now all the sudden concerned about it? And if they’re concerned about it now, that should cause everyone concern.

Further, if this was a bladder test because George has aircraft with bladders in it why would he wait until the fuel is approved and perform testing in someone else’s aircraft that he has minimal control over?

From my point of view, this was a PR “test”. They’re getting a different kind of awareness than they were probably hoping for.

 

[Jeff Oslick]

From my point of view, this was a PR “test”. They’re getting a different kind of awareness than they were probably hoping for.

An awareness that 50-year old, patched bladders can leak? Any bladder more than 30 years old should be considered working on borrowed time.

 

[mondtster]

An awareness that 50-year old, patched bladders can leak? Any bladder more than 30 years old should be considered working on borrowed time.

No. Awareness that the fuel actually exists (at least sort of) and that it isn’t just vaporware. People keep trying to claim this Baron is involved in some kind of “test”. I’m not convinced it is, as any testing necessary should have occurred before the STC was issued.


The reason I addressed bladders in the first place was because they are a mixed bag. Bladders from the 1950s are often in better shape and more repairable than ones that are much newer, thanks to the difference in materials used. It will be interesting to see how well the various materials withstand the new fuel in the real world; the bladders in my early Bonanza had never been out of the aircraft and didn’t leak when I sold it a couple of years ago. They were close to 70 years old at that point.

 

[Hang 4]

No. Awareness that the fuel actually exists (at least sort of) and that it isn’t just vaporware. People keep trying to claim this Baron is involved in some kind of “test”. I’m not convinced it is, as any testing necessary should have occurred before the STC was issued.

Well there's a million gallons in a tank in Louisiana produced by Vitol. The hold up is distribution. The why of that is less clear, but it appears that some of the majors and Swift are throwing up a ton of roadblocks. The majors have some leverage over the distributors and my guess would be that's the biggest issue.

The fuel was tested extensively as part of the STC process. The AOPA Baron is less a test and more a demonstration.

 

[Capt. Geoffrey Thorpe]

Obviously fake. The A-26 did not have dual controls.

"A World War II era medium bomber, the Douglas A-26 Invader took off Wednesday from its home base of Ada Regional Airport on a flight over Lake Atoka, Oklahoma, while operating on a unleaded fuel - G100UL high octane unleaded avgas"

G100UL

Find out more about GAMI's G100UL® high octane unleaded aviation gasoline.

www.g100ul.com

 

[SCCutler]

Obviously fake. The A-26 did not have dual controls.

"A World War II era medium bomber, the Douglas A-26 Invader took off Wednesday from its home base of Ada Regional Airport on a flight over Lake Atoka, Oklahoma, while operating on a unleaded fuel - G100UL high octane unleaded avgas"

G100UL

Find out more about GAMI's G100UL® high octane unleaded aviation gasoline.

www.g100ul.com

Plane seems pretty happy with it.