G100UL - fuel leak

[MikeOH]

2 minutes ago, Pinecone said:

And who is going to contract and pay for this testing?

 

Uh, the VENDOR/MFG!  Pretty common to pay INDEPENDENT test labs to run tests.

[Pinecone]

Uuh, GAMI has been doing that with many things.  GAMI is not a chemical testing laboratory.   And those things they tested (bladder degradation) were witnessed by 3rd party (FAA) observers.

[MikeOH]

1 minute ago, Pinecone said:

Uuh, GAMI has been doing that with many things.  GAMI is not a chemical testing laboratory.   And those things they tested (bladder degradation) were witnessed by 3rd party (FAA) observers.

It is not at all clear to me what tests GAMI performed in-house (which have an inherent conflict of interest) and those which were contracted to an outside lab.  Sorry, having the FAA oversee things does not give me warm & fuzzies (e.g. their 'oversight' of Boeing!)

[Pinecone]

Unlike Boeing, they were physically present at GAMI observing the tests.

GAMI did things like soak paint, bladder material, and sealants in the fuel.  Physical tests.

Chemical lab tests were by outside labs.

I have known George a long time, from AVSIG days.  First and foremost, George is a GA pilot and owner.  And has been for many years.  I cannot see him doing anything to harm GA and people's airplanes.

But also, you cannot test EVERY possible situation.  If someone used some shade tree mechanic sealant to patch some tanks, that is not aircraft approved, NO ONE has any way of knowing and testing such instances.

[EricJ]

25 minutes ago, Pinecone said:

And who is going to contract and pay for this testing?

 

Whoever wants results that are free of conflict of interest.

[gabez]

Quoting a response I got from AOPA:

"Thanks for contacting AOPA's Pilot Information Center. We're sorry to hear that you had issues with the G100 fuel. We haven't had any reports of paint damage/removal, other than staining when the fuel was exposed to sunlight. We tested the fuel in a Baron and had some observations/issues as well; https://www.aopa.org/news-and-media/all-news/2024/november/pilot/unleaded-fuel-what-we-have-learned ."

when you get the STC, you get a little package with the stickers as well as a pad to put on top of the fuel cap while fueling. It is marketed as refueling hygiene, I thought it was a california thing but obviously I was wrong. Attaching pics of the pad and the language around refueling hygiene. Please read. So the fuel will stain your paint unless you follow these steps. 

Still waiting from my IA/AP

[MikeOH]

6 minutes ago, Pinecone said:

Unlike Boeing, they were physically present at GAMI observing the tests.

GAMI did things like soak paint, bladder material, and sealants in the fuel.  Physical tests.

Chemical lab tests were by outside labs.

I have known George a long time, from AVSIG days.  First and foremost, George is a GA pilot and owner.  And has been for many years.  I cannot see him doing anything to harm GA and people's airplanes.

But also, you cannot test EVERY possible situation.  If someone used some shade tree mechanic sealant to patch some tanks, that is not aircraft approved, NO ONE has any way of knowing and testing such instances.

Let me put this another way: If it was some Big Oil company C-suite suit that was promoting G100UL would you be such a Kool-Aid drinking fan-boy?  I doubt it.

Telling me you know George or the Big Oil guy in the suit is NOT a compelling argument.

It's not a matter of if George, or anyone else, is out to harm anyone in GA or their aircraft (I don't believe he or anyone else is).  The ISSUE is two-fold: You cannot test EVERY possible situation (your words), and it is being FORCED upon us (e.g. RHV banning 100LL since G100UL is 'commercially available').

G100UL needs to be present in the FIELD for an extended period of time (several years, IMHO) alongside 100LL BEFORE 100LL is removed from the market.

IOW, I want to see some field beta testing by willing participants like yourself BEFORE I start using the fuel.  If it is an acceptable substitute the market will make it successful.

[Marc_B]

I think what most people realize is that most industries are somewhat self serving and some companies downright flaunt the lines of criminal. 

Remove GAMI from the situation and just say Product X and that they brought a product to market with extensive self directed tests that were loosely overseen or reviewed by the FAA for a focused population and then made broadly applicable to a much larger population unilaterally.

It's not conspiracy theory, its a distrust for the corporate workflow and not blankly wanting to accept "trust me, I'm one of you" to end up costing not just $100, but potentially more ($70K engine, $30K paint, $10K reseal).

In my mind, the manufacturers SHOULD be performing their own tests, and then the FAA/PAFI/EAGLE should be independently cross checking these with standard performance tests.  Instead you have a fuel industry that is likely intentionally interfering with testing and approval as the current product has a great profit margin and given that it's the de facto"Gold Standard", it has less liability.  (despite the fact that current fuel has many maintenance downsides that we've all just gotten used to).

The best way forward currently is for those who have access to, and want to use, alternative fuels to have a registry where they can report certain key maintenance events, keep pictures, and factually show presence or absence of issues with the available fuels.  Instead we have speculation and fear, and cases like UND that have some data but it's not really public.

The problem with just attributing ANY and every issues to GAMI isn't exactly scientific either.  "That leak was known but small" and now it's worse has tons of confounders.  Not a scientific test with n=1, but certainly something that can help highlight future testing and real world data needed.

My first thought was when was it resealed or factory sealant, who did the work, have there been any patching done, what products were used for patching, what was the worst amount of leaking already seen?  What paint was used, was there any existing filiform corrosion or poor adhesion under the paint, what was the overall condition of the paint and how was this progressing over the past year(s)?  One of the access panels looks like the paint was chipped off all around it, what was done there and why?

Speculation loves the anecdote, and you can point a story in any direction with limited information.

 

For those who use an alternative fuel, it would be nice to have a registry with details such as:  year of manufacturer of aircraft, year and type of paint, year and type of tank sealant/bladder, year and type of engine, and then have details for things such as overhaul and specs, factory new/reman engine, tank reseals or patching, and a gauge for overall condition of these items to begin with.  The FDA has FAERS "Adverse Event Reporting System" that comes to mind.  You can't know all the data, exhaustively, before you release a product.  You just can't.  But that doesn't mean that it shouldn't be tracked and checked by the FAA to determine what issues might pop up.

[MikeOH]

@Marc_B

Excellent post!

(Much more diplomatic than mine)

[AJ88V]

Glad to see this thread reopened, but kind of disappointed to see the harsh words towards GAMI and George Braly.  I suspect GAMI's development of G100UL is more of a search for an answer to a "known risk" that potentially affects all  piston aviation than some greedy corporate machinations to get rich (said another way, assume altruistic motives).

What we should be aggrieved about is a government (State of California) once again mandating a solution (NO LEAD) before there's a technical solution.  Yes, the government is providing a useful forcing function to get lead out of our environment (a very good thing), but then not providing much if any support to making it happen.  This is unlike say a "cure cancer moonshot" where lots of government resources are thrown at a problem or even a "no plastic bags" initiative where there are viable alternatives.  Nope, this is our government overlords mandating a magic solution and expecting it to be done, for a market (aviation fuel) which is too small to attract serious attention from the big players (the market for av fuel is actually pretty big nationally, but also miniscule compared to the automotive market).

As a hard sciences professional with more than a little chemistry, I'd bet it would be vastly easier to make an "even lower lead" fuel (100ELL) than to go straight to zero lead.  Maybe a 50-50 mixture of GAMI's G100UL with regular 100L would do it, and, from the environmental perspective, we could cut the lead content in half overnight! (from, what is nationally a drop in the bucket compared to other industrial waste issues).  Then they could phase in even lower lead solutions, on maybe a 10 year cycle.

So let's put the blame where it belongs: government-mandated overreach!

And thanks to GAMI and George Braly's passion for aviation to get us this far. </rant mode off>

[MikeOH]

@AJ88V

If your comment about "harsh words towards GAMI and George Braly" is in response to my post, I'd like to clarify.  I hold no animus towards George but I believe his motive in investing his time and money into developing G100UL is not any different than any other business; i.e. his motive, too, is profit.  Altruism has nothing to do with it.

And, I agree with you 100% on the government overreach; that's really the problem here.  The market should be allowed to work.

[AJ88V]

@MikeOH  No worries, brother!  I just get PO'd at things like "100% electric vehicles" and crap like that from the government.  But as bad as it is, we probably have the most permissive aviation support in the world here in the USA.  Maybe the Aussies are there with us.  Just grateful for what we've got and worry about encroaching government overreach.

[AJ88V]

PS @MikeOH  Keep thinking you're in "OH" as in Ohio, instead of California. You're far more affected by this cr@p than most of us. I'm sure Herr Meister Oberfuhrer Newsom and the Kalifornica legislature could give a rat's @ss about rich little airplane owners.  Sorry you have to be a guinea pig.

[redbaron1982]

The main thing I dislike about GAMI/George is that they always talk from this perspective: "We know everything; everyone else that doesn't say the same thing we do is wrong."

Not pursuing ASTM is one example of such an attitude; not investigating the issues starting to arise is another. They keep repeating the tests they did in the lab about paint and disregard what people are complaining about.

I value all the effort, investment, and time they put into this. And I believe we will have many benefits from switching to UL, not only environmental but maintenance as well.

[Shiroyuki]

10 minutes ago, redbaron1982 said:

The main thing I dislike about GAMI/George is that they always talk from this perspective: "We know everything; everyone else that doesn't say the same thing we do is wrong."

Not pursuing ASTM is one example of such an attitude; not investigating the issues starting to arise is another. They keep repeating the tests they did in the lab about paint and disregard what people are complaining about.

I value all the effort, investment, and time they put into this. And I believe we will have many benefits from switching to UL, not only environmental but maintenance as well.

This is spot on. 

[AJ88V]

8 minutes ago, redbaron1982 said:

The main thing I dislike about GAMI/George is that they always talk from this perspective: "We know everything; everyone else that doesn't say the same thing we do is wrong."

Not pursuing ASTM is one example of such an attitude; not investigating the issues starting to arise is another. They keep repeating the tests they did in the lab about paint and disregard what people are complaining about.

I value all the effort, investment, and time they put into this. And I believe we will have many benefits from switching to UL, not only environmental but maintenance as well.

These are also fair points.  Sorry if I came off holier than thou.

A lot of the problem is that things like ASTM certification quickly become a "rich man's game", and while GAMI is probably a decent money earner, I doubt they're that big.  Nobody in 'little aviation' is.  And even the big players (Shell, BP, Exxon, Phillips, etc.) are taking a pass on this one (no lead).  Corporately, manufacturing AvGas is probably more of a pain than a profit center.

 

[George Braly]

On 12/15/2024 at 11:44 PM, larryb said:

My aircraft, which I posted in #49 is a 1997 encore with factory paint. The paint missing around the rivets bubbled up and rubbed off 1 week after my first tank of GU100. The paint there was fine before but is is possible or likely the rivets seeped a bit of fuel before.

Regarding the drain port it is actually only a few years old. It was replaced under my ownership when the previous one leaked. Not sure why the current one is leaking, perhaps a bit of debris bought in the valve.

Larry,

Below is a report from Del Lehmann who has run a maintenance shop in Mena, Arkansas, for many many years.

He posted this on the BeechTalk Forum.  It is reproduced with his permission.

Note his comment about the construction method used at Mooney:

"Mooney riveted the wings together dry (no faying surface sealant), and then top coated the rivets and seams on the inside."  

That is not the industry standard method for constructing riveted integral wing tanks.  They should have used sealant when the placed the ribs into the structure and then riveted and then done the over coat with polysulfide sealant.  

Also note his observation that he is seating a lot of "old deteriorated / compromised sealant"  - -  before G100UL avgas was ever even approved. 

Del Lehmann's experience is consistent with our experience with an integral fuel tank we "re-worked" here at GAMI in a Piper Lance.  When we got that tank out, the sealant was so soft and "gooey" that you could scrape it up with a putty knife and smear it around between your thumb and finger.   On 100LL.  We re-sealed that tank and re-installed it and then we did some significant flight tests and detonation tests (Lycoming IO-540) using G100UL avgas,  with no further leaks. 

Also - - this is a  "Deja vu, all over again"  situation.  A very large number of the same Mooney fuel tank sealant failure issues came up during the 1980s due to the aging of that fleet and the deployment of 100LL which very often had very high levels of toluene in the production fuel.   There were also similar issues with some of the other "wet wing" fuel tanks in Pipers and some Cessna aircraft.  

Please let me know if you have more questions about this.

George

 

 

 

 

 

[donkaye, MCFI]

I like the potential benefits of G100UL.  I'll follow the fueling guidelines.  I've read all the documentation that came with the STC and have listened to George Braly's comments both in person and online and find them compelling.  My tanks were resealed by Paul at Weep no More in Willmar 8 years ago.  I was impressed by their process.  Notwithstanding some of the comments in this thread, I'll continue to use G100UL.

[redbaron1982]

2 hours ago, George Braly said:

Also - - this is a  "Deja vu, all over again"  situation.  A very large number of the same Mooney fuel tank sealant failure issues came up during the 1980s due to the aging of that fleet and the deployment of 100LL which very often had very high levels of toluene in the production fuel.   There were also similar issues with some of the other "wet wing" fuel tanks in Pipers and some Cessna aircraft.  

Reading this, I understand that there is some agreement that switching to G100UL could generate issues like the ones reported here. This statement says, "Hey, the same happened when we switched to 100LL".

Acknowledging that switching from 100LL to G100UL could make worse some already bad conditions of seals/paint, especially in wet-wing airplanes, would be a good starting point.

 

 

[PT20J]

I know most here think a  Mooney is just about perfect, but realistically it has flaws like everything else. We get mad at FBOs for damaging our poorly designed nose gear. There are at least three businesses that specialize in sealing Mooney fuel tanks and they do a booming business. The design of the wing makes the integrity of the seal strongly dependent upon the skill of the person applying it. From a process control standpoint, that’s going to introduce a lot of variation in the result. 

[redbaron1982]

And we are back online!

It looks like George is not so friendly with Mooney's design over on AvWeb.

Anyway, my take is this: who is the new kid on the block? Is it the Mooney wet-wing design or is it G100UL? If Mooney wings start leaking more fuel than before, it's not its design, but due to the new G100UL.

Doesn't mean that G100UL is useless or should be banned... it is just different than 100LL and it's better in some ways (more oil life) and worse in others (tanks leaking more than they used to).

[Shiroyuki]

13 hours ago, George Braly said:

Larry,

Below is a report from Del Lehmann who has run a maintenance shop in Mena, Arkansas, for many many years.

He posted this on the BeechTalk Forum.  It is reproduced with his permission.

Note his comment about the construction method used at Mooney:

"Mooney riveted the wings together dry (no faying surface sealant), and then top coated the rivets and seams on the inside."  

That is not the industry standard method for constructing riveted integral wing tanks.  They should have used sealant when the placed the ribs into the structure and then riveted and then done the over coat with polysulfide sealant.  

Also note his observation that he is seating a lot of "old deteriorated / compromised sealant"  - -  before G100UL avgas was ever even approved. 

Del Lehmann's experience is consistent with our experience with an integral fuel tank we "re-worked" here at GAMI in a Piper Lance.  When we got that tank out, the sealant was so soft and "gooey" that you could scrape it up with a putty knife and smear it around between your thumb and finger.   On 100LL.  We re-sealed that tank and re-installed it and then we did some significant flight tests and detonation tests (Lycoming IO-540) using G100UL avgas,  with no further leaks. 

Also - - this is a  "Deja vu, all over again"  situation.  A very large number of the same Mooney fuel tank sealant failure issues came up during the 1980s due to the aging of that fleet and the deployment of 100LL which very often had very high levels of toluene in the production fuel.   There were also similar issues with some of the other "wet wing" fuel tanks in Pipers and some Cessna aircraft.  

Please let me know if you have more questions about this.

George

 

 

 

 

 

 

11 hours ago, redbaron1982 said:

Reading this, I understand that there is some agreement that switching to G100UL could generate issues like the ones reported here. This statement says, "Hey, the same happened when we switched to 100LL".

Acknowledging that switching from 100LL to G100UL could make worse some already bad conditions of seals/paint, especially in wet-wing airplanes, would be a good starting point.

 

 

We all know mooney’s tank will leak eventually because of poor design choice, however that doesn’t mean it is ok for G100UL to shorten a sealants life span.

if some old sealant works fine with 100LL and suddenly starts leaking with G100UL, that’s a problem, and owners deserve to be warned about it before using the fuel.

A slightly weeping wing may last another five or ten years on 100LL, and if switching G100UL kills it in three month, don’t blame it on Mooney or the fuel tank.

And tbh this whole argument is not about old deteriorating sealant, it’s about g100ul making otherwise not leaking old sealant leak…. Same for the paint…

we need a clear answer if the fuel hurts sealant and paint rather then simply blaming it on old paint and old sealant. Also due to conflict of interest I’d like to see test results from third party lab…

this whole thread is going nowhere with one side blaming mooney’s tank design, old sealant, and some plane’s old paint.

[Ibra]

13 hours ago, PT20J said:

There are at least three businesses that specialize in sealing Mooney fuel tanks and they do a booming business. The design of the wing makes the integrity of the seal strongly dependent upon the skill of the person applying it. From a process control standpoint, that’s going to introduce a lot of variation in the result. 

Those are wise words, it's hard to cater for all variations in fleet when designing new fuel specs: one has to assume that a Mooney (or any other aircraft) that is taking G100UL (or any other fuel) has an approved sealant with tanks being resealed to a high standards. For these, I would expect, 100LL and G100UL will have the same results, then life carry as before 

For Mooneys that falls out of specs, it's hit and miss with learning curve while we are "in-transition."  Anyone with a background in risk engineering will have to accept that testing involves different sensitivities, thresholds, and confidence levels.

The point about toluene (%) variations (in 100LL and G100UL or whatever fuel) is something one should watch for, especially, if they are differing tank reseals or using non specialised shop

It's hard to make binary YES or NO statements, let's leave this to general public or politicians who love binary stuff: "no 100LL in California next year", "drop-in replacement as is", "let's ban TEL",...So far, one need more data on both Mooneys that showed problems and those that don't and figure out why? GAMI offer to look on a case by case seems reasonable on how one should approach the problem, then it's wait and see 

I suspect Mooneys and other wet wing designs (especially +30 years vintages like mine) could have higher sensitivity to toluene (%) than other airframes 

Edited December 19, 2024 by Ibra

[McMooney]

On 12/18/2024 at 9:50 AM, AJ88V said:

Glad to see this thread reopened, but kind of disappointed to see the harsh words towards GAMI and George Braly.  I suspect GAMI's development of G100UL is more of a search for an answer to a "known risk" that potentially affects all  piston aviation than some greedy corporate machinations to get rich (said another way, assume altruistic motives).

What we should be aggrieved about is a government (State of California) once again mandating a solution (NO LEAD) before there's a technical solution.  Yes, the government is providing a useful forcing function to get lead out of our environment (a very good thing), but then not providing much if any support to making it happen.  This is unlike say a "cure cancer moonshot" where lots of government resources are thrown at a problem or even a "no plastic bags" initiative where there are viable alternatives.  Nope, this is our government overlords mandating a magic solution and expecting it to be done, for a market (aviation fuel) which is too small to attract serious attention from the big players (the market for av fuel is actually pretty big nationally, but also miniscule compared to the automotive market).

As a hard sciences professional with more than a little chemistry, I'd bet it would be vastly easier to make an "even lower lead" fuel (100ELL) than to go straight to zero lead.  Maybe a 50-50 mixture of GAMI's G100UL with regular 100L would do it, and, from the environmental perspective, we could cut the lead content in half overnight! (from, what is nationally a drop in the bucket compared to other industrial waste issues).  Then they could phase in even lower lead solutions, on maybe a 10 year cycle.

So let's put the blame where it belongs: government-mandated overreach!

And thanks to GAMI and George Braly's passion for aviation to get us this far. </rant mode off>

I can't seem to fault California,  i'm gonna just guess it's been approx 40+, repeat 40+ years we've been transitioning away from leaded fuels, why shouldn't they say it's been long enough?  be honest, the only people that care about aviation in california are kids and pilots, the rest want to replace your airports with strip malls and housing.  

[Marc_B]

@Ibra I'm not exactly sure what to make of Mr. Braly's comments regarding Toluene vs Xylene.  His comment seems to imply that 100LL is more of a solvent than G100UL and infers that 100LL is more likely to damage sealant or paint rather than G100UL.  It's hard to say what is exactly in a mix of fuel without testing that sample and there no precise consistency from mix to mix.  One can easily pull the SDS for both 100LL and G100UL, but this may not truly reflect the average batch.

But the 29% Mr. Braly quoted may not be reflective of the typical fuel you see at the pump and it's hard to say what the spec for the California batches of G100UL were...has anyone tested this fuel for comparison?  Might be helpful...Mr. Braly has this information.

100LL SDS:

G100UL SDS:

At least from the SDS, it appears overall 100LL has much less Xylene+Toluene than G100UL.  I'm not suggesting that this is causal to anything, but just trying to reconcile and understand Mr. Braly's comments regarding Borger Phillips 66 100LL sample and extrapolating that to the 100LL fuel in general and somehow saying G100UL has less = safer for equipment?

As an aside, is it even established that it's (edit: ONLY) Toulene that's causing damage to sealant/paint?