Based on the G100UL fuel leak thread what's your position?

[redbaron1982]

2 minutes ago, Pinecone said:

Yes, and have been flying in planes without changing the O-rings for those same number of years.

The paint stripping seems to be when there is a slight leak and the fuel is allowed to sit, WET, for periods of time

How do you know they haven´t changed o-rings?

[Pinecone]

Do you think they are stupid enough to know about the O-rings and not said anything? 

It is not like it would not come out.  And now a lot more planes are using it, and no reports of O-ring issues?

The recommendation for Vitron sounds like they know they may swell, but not that there are big issues.

[Schllc]

After watching that YouTube video I can’t believe this didn’t come up in gami’s testing. 
that experiment is damning. I have zero interest in using g100ul until they resolve this issue. 

[MikeOH]

14 minutes ago, Pinecone said:

Do you think they are stupid enough to know about the O-rings and not said anything? 

It is not like it would not come out.  And now a lot more planes are using it, and no reports of O-ring issues?

The recommendation for Vitron sounds like they know they may swell, but not that there are big issues.

I will say, your ability to turn your eyes away from that video is quite impressive!  As even @GeeBee said, "That is some disturbing results"... yet you soldier on with no concerns; amazing!

[Marc_B]

Out of curiosity, does anyone know how the underside of the AOPA Baron wings are fairing? I know the original issue was reported as fuel bladder leaks but asking if since then have noted any damage to the paint under the wing?

Seems like there would be a case control there as well as both bladders were leaking…one 100LL and the other G100UL. 

[EricJ]

3 hours ago, Pinecone said:

Do you think they are stupid enough to know about the O-rings and not said anything? 

Braly said at the session I attended at the Buckeye Air Fair, to not get it on your paint and it may be harsher on seals and gaskets.   I got the impression that he was understating things, because he was there to promote the fuel.  

I suspect they knew.   They may have just been hoping it wouldn't be bad.  Since he promotes the stuff, he's not going to be the one who sheds much light on the downsides.  

3 hours ago, Pinecone said:

It is not like it would not come out.  And now a lot more planes are using it, and no reports of O-ring issues?

Those may take more time to appear.    I hope the issues won't be found as the result of incidents, but that may very well be what happens.

3 hours ago, Pinecone said:

The recommendation for Vitron sounds like they know they may swell, but not that there are big issues.

There are lots of important seals, gaskets, and hoses in the fuel system.    It doesn't take much of a problem to become a "big issue".

It's also a little scary that this stuff hasn't been out in the wild for very long, and already we're seeing some important drawbacks.   The o-rings are a significant issue, and there's also any lurking issues for materials that haven't been tested, like cork seals, gaskets, other materials, etc.    In the latest vid, 100% of the items tested essentially failed in the presence of G100UL.   I don't think that means that everything else is going to be okay.

 

[MikeOH]

The most shocking aspect of that video was how little time was required for significant damage to occur.

Actually, that may be a good thing; I'd rather the problems quickly manifest themselves versus more subtle, long term failures that could be falsely attributed to other causes.

[EricJ]

24 minutes ago, MikeOH said:

The most shocking aspect of that video was how little time was required for significant damage to occur.

Actually, that may be a good thing; I'd rather the problems quickly manifest themselves versus more subtle, long term failures that could be falsely attributed to other causes.

The effects on other materials are still not evident.   It could be that degradation in things with other materials like hoses, gaskets, whatever, may be slower and create more latent failures over time.   I'm worried for people who use this that might experience in-flight failures due to latent issues from seal, hose, or gasket degradation over time.

Since hearing Braly talk at Buckeye I've been suspicious that this might be the way this all goes, i.e., it's not ready or not good for the fleet, or just not a good solution or even the best solution to the problem.   It is the solution that has had a vocal advertiser and self-promoter, and that's really the main thing that appears to have been propelling it.

Since the current formulation is what has been approved, I don't think there's an easy path for a reformulation that will correct these issues.   A different formulation may need to go through all the testing again and re-apply for approval and result in a different STC due to a different specification.   G100UL is probably only going to be what it is now, and that appears to be pretty undesirable, especially with the unknowns regarding other materials in the fuel systems, including sealant.

I'm not personally worried, because the remaining players in the US are experienced fuel formulators and distributors, and are taking their time with a longer process.   That's not a bad thing, that's a good thing, as we're more likely to wind up with solution(s) that are closer to a drop-in replacement than G100UL appears to be.

[Marc_B]

There are comments about o-rings and hoses in the G100UL ICA, but it comments when replacing as practical, rather than ensure your equipment does not have....

HANDLING, SERVICE AND MAINTENANCE OF AIRCRAFT AND ENGINES WITH G100UL Avgas
Storage and handling G100UL Avgas is the same as for other aviation grade fuels. All precautions and warnings that apply to 100LL also apply to G100UL.
When replacing seals or O-rings in the fuel systems of aircraft or engines operating on G100UL Avgas replace Buna N or nitrile fuel system components with components made of silicone or fluoropolymer elastomers (such as Viton) where practical.
When replacing flexible fuel hose assemblies utilize tetrafluoroethylene (Teflon) lined hose assemblies per TSO C53a or TSO C140 where practical.

https://www.g100ul.com/dl/GAMI G100UL ICA Rev C.pdf

[Z W]

I learned some things about O-rings from all this. I guess I shouldn't be surprised the world continues to use and sell inferior-grade materials that are a few pennies cheaper.

Viton O-rings appear to be easily available for purchase for not a lot of money.

[Sabremech]

11 minutes ago, Z W said:

I learned some things about O-rings from all this. I guess I shouldn't be surprised the world continues to use and sell inferior-grade materials that are a few pennies cheaper.

Viton O-rings appear to be easily available for purchase for not a lot of money.

We use the part numbers listed in the relevant IPC. When I order o-rings, I don’t get to specify what it’s made from. Unless the manufacturer updated their IPC to include alternate P/N’s made from different materials, we risk not using the correct parts and potentially causing other issues, which could be catastrophic. 

[Z W]

Mr. Braley posted some guidance from the FAA recommending replacing nitrile O-rings with equivalent Viton or Fluorosilicone. I'm certain some A&P legal scholars will weigh in soon, but I believe there's an accepted practice to do that.

Not recommending anyone go out and install the wrong O-rings in their plane.

[tony]

On 12/22/2024 at 10:57 PM, MikeOH said:

You can laugh but I suspect I am not the only one that feels that way.  None of your present poll choices apply to this situation.

You're absolutely correct, you're not.  It needs to be certified the correct way.  Not pencil whipped because of politics

[tony]

20 hours ago, gabez said:

how does it work if the claim was G100UL is drop in with an STC and then it is not? do they pull the STC? 

then probably issue an AD to inspect.....lol

[tony]

20 hours ago, redbaron1982 said:

And I want to reiterate: there is no chance, not in a million years, that GAMI was not aware of this. They have been experimenting with this stuff for more than 10 years, I'm sure they have all the information, but they decide which to share and which to keep for themselves.

prove that and the lawsuits will put GAMI out of business....

[tony]

32 minutes ago, Z W said:

Mr. Braley posted some guidance from the FAA recommending replacing nitrile O-rings with equivalent Viton or Fluorosilicone. I'm certain some A&P legal scholars will weigh in soon, but I believe there's an accepted practice to do that.

Not recommending anyone go out and install the wrong O-rings in their plane.

A recommended practice to deviate from the type design with no paper work to back up the change?

[A64Pilot]

20 hours ago, N201MKTurbo said:

There isn't that many in the Lycomings. There are some in the fuel selector, some in the fuel pump fittings and a few in the servo. 6-8 hours of labor.

Depending on the aircraft, I have bladders for instance there are more O-rings than we might think, I’m sure fuel caps have them too etc.

I’ve not watched the video, but strongly suspect something isn’t Kosher with it, O-rings are surely about the first things you would check, and are among the easiest. I’d bet Lunch Gami tested both new and used O-rings many years ago, along with fuel lines and sealant.

I can’t believe they missed that and suggesting they knew and drove on anyway is suggesting they are both crooks and stupid ones at that as of course that’s going to become apparent soon and kill their product, probably have them in many courts, bankrupt the company and kill any trust the community had in them.

I don’t think they are that stupid myself.

Having said all of that even if it were available to me I won’t be an early adopter. The Mobil 1 issue comes to mind, so even unlikely things are possible.

I have become over the years very distrustful of the FAA overseeing anything, their stamp of approval doesn’t mean what it used to.

[A64Pilot]

19 minutes ago, tony said:

A recommended practice to deviate from the type design with no paper work to back up the change?

There are many practices like that, like to replace a Goodyear tire with a Michelin etc. You can replace an AN bolt with a NAS etc, because the NAS is “better”. I believe Viton unless for some reason is disallowed is “better”

But I believe that for whatever reason if the fuel is eating O-rings then there just might be an AD requiring O-ring replacement, then you have your paperwork.

As an IA I would have no problem with Viton, I serviced my Gascolator yesterday, replaced the big O-ring and Stat-O-Seal and went to replace the tiny one on the pull to drain, noticed it was brown meaning it’s was Viton so I left it. I bet that Viton one will outlive me, I’ve never seen one deteriorate, I’ve only seen a few mechanically worn is all.

[tony]

7 minutes ago, A64Pilot said:

There are many practices like that, like to replace a Goodyear tire with a Michelin etc. You can replace an AN bolt with a NAS etc, because the NAS is “better”. I believe Viton unless for some reason is disallowed is “better”

But I believe that for whatever reason if the fuel is eating O-rings then there just might be an AD requiring O-ring replacement, then you have your paperwork.

As an IA I would have no problem with Viton, I serviced my Gascolator yesterday, replaced the big O-ring and Stat-O-Seal and went to replace the tiny one on the pull to drain, noticed it was brown meaning it’s was Viton so I left it. I bet that Viton one will outlive me, I’ve never seen one deteriorate, I’ve only seen a few mechanically worn is all.

I posted this in another string but how did GAMI show compliance to 23.961 for an entire fleet of aircraft?

[A64Pilot]

I’ve done hot fuel testing, it’s an airframe requirement, not I believe a fuel requirement.

For example one of the tests I did was to qualify the S2R-T660 which is a turbine for 100LL, because Pratt allows limited use of 100LL as an emergency fuel. 

Having said that the STC process from my experience is pretty “flakey” for example at one time there was an STC to put a C-140 into LSA by putting a placard on the airplane restricting its gross weight to the LSA limited.

FAA later rescinded that STC.

The Auto fuel STC’s I believe did do specific testing to each airframe, because several airframes require modifications to run it, most I believe to prevent vapor loc, so there had to be airframe hot fuel testing to qualify that.

I assume with no knowledge that Gami showed that their fuel due to vapor pressure was less likely to vapor lock than 100LL.

Edited December 25, 2024 by A64Pilot

[takair]

After watching the video, I’d be most curious if STC testing was done on the various diaphragms in things like the Bendix fuel injection systems and pressure carbs.  I think our common fuel injector servo has at least three diaphragms.  The pressure carb on some other aircraft is full of rubber seals and diaphragms that are sensitive to age, assembly and abuse.  Both have serious failure modes if the diaphragms are compromised.  I’m not sure what would happen with swelling or pliability.  

[Shiroyuki]

56 minutes ago, A64Pilot said:

Depending on the aircraft, I have bladders for instance there are more O-rings than we might think, I’m sure fuel caps have them too etc.

I’ve not watched the video, but strongly suspect something isn’t Kosher with it, O-rings are surely about the first things you would check, and are among the easiest. I’d bet Lunch Gami tested both new and used O-rings many years ago, along with fuel lines and sealant.

I can’t believe they missed that and suggesting they knew and drove on anyway is suggesting they are both crooks and stupid ones at that as of course that’s going to become apparent soon and kill their product, probably have them in many courts, bankrupt the company and kill any trust the community had in them.

I don’t think they are that stupid myself.

Having said all of that even if it were available to me I won’t be an early adopter. The Mobil 1 issue comes to mind, so even unlikely things are possible.

I have become over the years very distrustful of the FAA overseeing anything, their stamp of approval doesn’t mean what it used to.

If you can get your hand on some G100UL it wouldn’t be difficult to validate that YouTube test yourself.. just buy some print and submerge them inside.

Id love to try but I’m not aware anywhere near me that has a G100UL pump.

[A64Pilot]

25 minutes ago, Shiroyuki said:

If you can get your hand on some G100UL it wouldn’t be difficult to validate that YouTube test yourself.. just buy some print and submerge them inside.

Id love to try but I’m not aware anywhere near me that has a G100UL pump.

I don’t either, and not to be insensitive as of yet I don’t have a dog in the fight. I figure by the time it’s forced onto me that it will have been well tested by lots of souls.

As I said I have not watched the video, but I can’t imagine someone with a few jars has discovered an obvious defect in this fuel, something that any compatibility testing  would have discovered the problem, and I’m certain that compatibility testing was done years ago, before it was ever put into an airplane surely.

As far as the recommendation to upgrade the rubber in the fuel system, yeah that’s worrisome, but it could be argued as simply good advice too Viton where allowed and Teflon lines are superior products from my experience. O-rings etc could cause serious problems even engine failures, but I think the biggest $$$ concern is bladders and fuel tanks.

Youtube is so full of BS, with all kinds of people claiming all kinds of nonsense, all seeking their 30 sec of fame that it’s just sad. I guess I’ll watch the video and give him another click or hit or whatever it’s called

[A64Pilot]

I think it’s likely that we have enough people burning this stuff that we will have a good indicator of problems before long, at least in California climate anyway. That’s the acid test in my opinion, I’m just too risk adverse myself to willingly participate

[A64Pilot]

OK, I watched the video.

I don’t think he’s a nut searching for hits or whatever they are called.

Personally I wouldn’t put this stuff in my lawnmower if I had an option not too just based on that Video

Paint I think isn’t a significant issue, but I have a LOT of experience with Jet-Glo, it’s one of the paints that tolerates chemicals used in Aerial application, and some of those even eat fuel tank sealer, we used fuel tank sealer in the chemical hopper and it would get eaten up and need replacing regularly, but we never found anything better, anything that dissolves or eats up Jet-Glo is something that will likely have adverse effects on just about anything.

Paint staining is an annoyance but it won’t hurt you, swelling fuel system “rubber” components can

There are seals, O-rings throughout many fuel systems, some you can’t change out, like fuel flow senders for instance, there are plastics in places you wouldn’t think of too. I’ve seen plastic bushings etc in fuel pumps for instance so add pumps to the list of fuel system “rubber”

Edited December 25, 2024 by A64Pilot