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

[Paul Thomas]

19 minutes ago, ragedracer1977 said:

Probably sealed the tanks with latex caulk and painted the plane with a roller.

 

 

Do you know anything about RV tank construction? I'd argue that RV tank build design/construction method is better than ours and use similar products. When those tank leaks, it's normally like ours and not such a big leak.

It may very well turn out that this particular airplane was not built to spec which and the leak is due to that component failing but it's not a good look.

[ragedracer1977]

I’m currently building an RV14.  If I write my operating limitations to include g100ul, how would I buy fuel?

i don’t need an STC. 

[ragedracer1977]

4 minutes ago, Paul Thomas said:

Do you know anything about RV tank construction? I'd argue that RV tank build design/construction method is better than ours and use similar products. When those tank leaks, it's normally like ours and not such a big leak.

It may very well turn out that this particular airplane was not built to spec which and the leak is due to that component failing but it's not a good look.

I was being sarcastically proactive. I thought that would be obvious haha

[Marc_B]

I've read some pilots question if maybe it's better to slowly integrate G100UL so that the aromatic hydrocarbon content slowly rises vs. just go from an empty tank of 100LL to a full tank of G100UL.  i.e. "don't shock the seals"...Be interesting to see this studied.

This may not be unique to G100UL either...i.e. we've yet to see the introduction of a fuel with dramatically lower aromatic content than standard 100LL (which may be possible with other "octane" component fuels).  But it's clear that G100UL has higher aromatic content than 100LL and xylene affects seal swell to a higher degree than does toluene.

But before anyone goes out and tries to switch all their o-rings/hoses/seals/etc...there's probably some knowledge we need to develop to bridge that gap successfully.

https://www.cambridge.org/core/journals/aeronautical-journal/article/investigation-on-elastomer-behaviour-when-exposed-to-conventional-and-sustainable-aviation-fuels/0863C07931DFA895AC87381992D47778 

"Despite the extensive volume of research on seal swell, it remains evident that the amount and rate of seal swell is highly dependent upon seal material. Adams et al. studied a range of elastomers in fuels of varying aromatic content, and those tests revealed that swell was proportional to the aromatic content."

"A review of published studies on elastomer compatibility with aviation fuels highlights certain knowledge gaps which must be addressed. Standardisation for testing the complex interactions between O-rings and different fuels is available in various ASTM documents. These standards define test methods and equipment used by researchers to validate their data. However, some elastomer test methods are outdated and may not represent on-wing applications. Furthermore, knowledge gaps may also arise since ASTM standards call for the selection of single O-rings from each chemical family. An assumption is made that results obtained on the selected O-ring are representative of the entire polymer group, and this may not necessarily be valid."

[Marc_B]

28 minutes ago, Paul Thomas said:

It may very well turn out that this particular airplane was not built to spec which and the leak is due to that component failing but it's not a good look.

I think this hints at the liability that an owner is assuming with using a new fuel, especially with an experimental.  There will always be assumptions that it was due to improper maintenance and improper construction.  So there would probably be a larger "burden of proof" required for an experimental owner to recover any damages.

From the "Opposition To Motion..." paper:

"At present, the supplier of G100UL, Vitol Aviation (“Vitol”) warrants only that G100UL conforms to the G100UL Specification."

"Indeed, Vitol appears to limit the product liability coverage it offers to the greater of $250,000 or the purchase price of G100UL, an amount that would not remotely offer sufficient coverage in the event G100UL caused a serious safety incident or significant damage to planes."

[Echo]

On 1/11/2025 at 3:08 PM, IvanP said:

Thinking about the STC process for being able to use UL fuel in our current planes, regardless of who makes it. We now have the option to purchase STC for G100UL. If, hypothetically, other companies put out UL fuels that will become "commerically available" for use by GA fleet, will we have to purchase STC from each of the respective vendors? 

I have no issue paying for STC that involves parts and/or actual modification of the aircraft, e.g., Monroy tanks, GAMI injectors, etc., but I have an issue with paying hundreds of dollars for couple of stickers to the compay that also charging us for their fuel which is more expensive than other available fuel.  It seems that making the STC free would be a smart move from marketing standpoint. I know that few pilots got "free" STC at KRHV when they purchased enough G100UL. In the grand scheme of things, the company will make much more money from fuel sales than from the on-time STC sale and it would probably be received well by pilots.  

 

That’s a bingo

[EricJ]

2 hours ago, Marc_B said:

GAMI has said that G100UL was sent to Continental and Lycoming and years later was returned unopened (paraphrasing here not sure on exact details).  The "Settling Defendents Opposition to Motion..." suggests that requirements of a gag-restriction was part of/the reason this testing wasn't performed.  I haven't read about that before and curious if this is true and if standard practice that Continental and Lycoming could test something to be used in their engines but not disclose the results of said testing to FAA or owners...seems that would run counter to the AD/SB process if an issue was discovered.

"Lycoming advises that, because GAMI insists on a “gag-restriction” that prevents it from sharing
“appropriate guidance to the FAA, the industry, and the flying public,” it has not yet had the
opportunity to evaluate G100UL’s “material compatibility, evaluation of toxicity, engine testing
for detonation, endurance, flight testing and operability; as well as review of operational concerns
to determine that [G100UL] is fit for purpose.” Hoyt Decl. ¶ 17, Ex. B."

Also from the same document:

"The two largest OEMs of the engines placed in these aircrafts have also refused to approve
G100UL. Lycoming Engines, which has been producing piston aviation engines for over 95 years,
has expressed a willingness to independently review technical documentation regarding G100UL,
but GAMI has refused to share this information unless Lycoming agrees to a “gag-restriction” that
would prohibit Lycoming from disclosing any of its findings, including any adverse safety findings
to FAA. See Hoyt Decl. Ex. B (Lycoming Service Advisory). As a result, Lycoming cannot
undertake the “rigorous evaluation” of G100UL necessary to conclude that it can be safely used in
its engines, and Lycoming has not added G100UL to its approved fuel list. Id. Because Lycoming’s
warranty coverage excludes damages caused by fuels that are not on this list, any pilot who uses
G100UL would void the engine warranty. Id. The other OEM of aircraft engines, Continental
Aerospace Technologies, has likewise refused to add G100UL to its approved fuel list or extend its
warranty coverage to the use of G100UL. Hoyt Decl. ¶ 17."

Another pertinent tidbit from the filing is that the CA legislature didn't view GAMI as qualifying as a "commercially available fuel" since it doesn't conform to an ASTM specification:

"The Legislature also addressed “commercial availability,” reasoning that G100UL will not become
“commercially available” until it obtains an ASTM Specification:

The FAA’s approval of an unleaded avgas for use in these aircraft is an important first
step in the process of transitioning to an unleaded fuel for the entire GA fleet, but it is not
the only step needed to ensure a safe transition. Fuel distributors and FBOs lack safety
assurance without an industry consensus standard or ASTM International product
specification. At present, G100UL is not commercially available for distribution and
sale in the U.S. largely due to the fact that it does not have an ASTM International
product specification."

 

[redbaron1982]

55 minutes ago, EricJ said:

Also from the same document:

"The two largest OEMs of the engines placed in these aircrafts have also refused to approve
G100UL. Lycoming Engines, which has been producing piston aviation engines for over 95 years,
has expressed a willingness to independently review technical documentation regarding G100UL,
but GAMI has refused to share this information unless Lycoming agrees to a “gag-restriction” that
would prohibit Lycoming from disclosing any of its findings, including any adverse safety findings
to FAA. See Hoyt Decl. Ex. B (Lycoming Service Advisory). As a result, Lycoming cannot
undertake the “rigorous evaluation” of G100UL necessary to conclude that it can be safely used in
its engines, and Lycoming has not added G100UL to its approved fuel list. Id. Because Lycoming’s
warranty coverage excludes damages caused by fuels that are not on this list, any pilot who uses
G100UL would void the engine warranty. Id. The other OEM of aircraft engines, Continental
Aerospace Technologies, has likewise refused to add G100UL to its approved fuel list or extend its
warranty coverage to the use of G100UL. Hoyt Decl. ¶ 17."

Another pertinent tidbit from the filing is that the CA legislature didn't view GAMI as qualifying as a "commercially available fuel" since it doesn't conform to an ASTM specification:

"The Legislature also addressed “commercial availability,” reasoning that G100UL will not become
“commercially available” until it obtains an ASTM Specification:

The FAA’s approval of an unleaded avgas for use in these aircraft is an important first
step in the process of transitioning to an unleaded fuel for the entire GA fleet, but it is not
the only step needed to ensure a safe transition. Fuel distributors and FBOs lack safety
assurance without an industry consensus standard or ASTM International product
specification. At present, G100UL is not commercially available for distribution and
sale in the U.S. largely due to the fact that it does not have an ASTM International
product specification."

 

It's unbelievable the gag restriction to report any negative findings. It's truly amazing. It's really hard for me to trust GAMI or anyone supporting this way of doing business. 

It doesn't surprise me though, because it kind of aligns with the denial and elusive answers in this forum to the sealant compatibility and the paint peeling issues reported. 

[George Braly]

5 hours ago, Marc_B said:

With regards to a pilot using a new fuel with limited fleet testing, with limited liability coverage from the manufacturer/supply stream, without an approved STC...that's just a special kind of poor ADM in my mind.   (regardless of being "caught" by enforcement)

You are misinformed.  There is standard liability coverage for the fuel being sold to the FBOs in California and elsewhere.  Identical or essentially identical to that presently in place for most of the FBOs selling 100LL. 

[Z W]

For those quoting the filing in opposition to the motion to enforce the settlement - 

You're quoting a lawyer hired to obtain a result (avoid enforcement of the settlement). They've written it very well and did a good job. However, the "facts" you are quoting cite mostly to one or two "declarations" - e.g. "Hoyt Decl. ¶ 17." A declaration is an unsworn statement written out by a witness related to the lawsuit. Sometimes they do have them sworn under oath, which technically makes it an affidavit and not a declaration, but that's not all that important. The point is, you're quoting a statement by someone named "Hoyt" that summarizes the positions of third parties not involved (Lycoming, Continental, Textron, Piper, etc.) that was carefully edited, if not outright written, by their lawyers. It's an out-of-court statement with two or sometimes three layers of hearsay. And now being repeated over the internet.

Any lawyer or judge knows those statements are not admissible in court at an actual hearing or trial, and also knows these types of pre-trial filings are often full of inaccurate or false statements that don't bear out. It's a lot of pre-trial posturing.

I don't know how much of any of it is true, and neither do any of you. I personally will keep an open mind.

[GeeBee]

The idea that there will be a fair hearing and trial of fact on an environmental matter in a court room, let alone a California court room I find "quaint". 

 

[redbaron1982]

Not sure if this was already shared here: https://www.lycoming.com/fuels

"To ensure the safety of the flying public and to meet its obligations as a TC holder, Lycoming has refused this “gag-restriction.” If we determine that any candidate fuel creates a safety issue when used in our engines, we must be able to appropriately warn the public and the FAA."

 

[gabez]

My mechanic has officially opened the tanks, drained the fuel and he is going through the plane. Hopefully by this Friday I will have a summary of what's going on

[ragedracer1977]

3 hours ago, Z W said:

For those quoting the filing in opposition to the motion to enforce the settlement - 

You're quoting a lawyer hired to obtain a result (avoid enforcement of the settlement). They've written it very well and did a good job. However, the "facts" you are quoting cite mostly to one or two "declarations" - e.g. "Hoyt Decl. ¶ 17." A declaration is an unsworn statement written out by a witness related to the lawsuit. Sometimes they do have them sworn under oath, which technically makes it an affidavit and not a declaration, but that's not all that important. The point is, you're quoting a statement by someone named "Hoyt" that summarizes the positions of third parties not involved (Lycoming, Continental, Textron, Piper, etc.) that was carefully edited, if not outright written, by their lawyers. It's an out-of-court statement with two or sometimes three layers of hearsay. And now being repeated over the internet.

Any lawyer or judge knows those statements are not admissible in court at an actual hearing or trial, and also knows these types of pre-trial filings are often full of inaccurate or false statements that don't bear out. It's a lot of pre-trial posturing.

I don't know how much of any of it is true, and neither do any of you. I personally will keep an open mind.

The link to lycomings public statement about the gag-restriction gives this Hoyt person a little credibility 

[redbaron1982]

Looks like GAMI is already aware of RV issues too:

[EricJ]

3 hours ago, Z W said:

For those quoting the filing in opposition to the motion to enforce the settlement - 

You're quoting a lawyer hired to obtain a result (avoid enforcement of the settlement). They've written it very well and did a good job. However, the "facts" you are quoting cite mostly to one or two "declarations" - e.g. "Hoyt Decl. ¶ 17." A declaration is an unsworn statement written out by a witness related to the lawsuit. Sometimes they do have them sworn under oath, which technically makes it an affidavit and not a declaration, but that's not all that important. The point is, you're quoting a statement by someone named "Hoyt" that summarizes the positions of third parties not involved (Lycoming, Continental, Textron, Piper, etc.) that was carefully edited, if not outright written, by their lawyers. It's an out-of-court statement with two or sometimes three layers of hearsay. And now being repeated over the internet.

Any lawyer or judge knows those statements are not admissible in court at an actual hearing or trial, and also knows these types of pre-trial filings are often full of inaccurate or false statements that don't bear out. It's a lot of pre-trial posturing.

I don't know how much of any of it is true, and neither do any of you. I personally will keep an open mind.

Yes to the above.   It is, however, one of the few glimpses that we've gotten into the other side of the story.   Only hearing one side for a long time isn't good for informed decision making.    As shown above via the link directly to Lycoming's site on the topic, the quotes in the filing track very closely to Lycoming's statements on their website.  

[Marc_B]

3 hours ago, Z W said:

I don't know how much of any of it is true, and neither do any of you.

exactly why I posted it...is it true and what's the background?  The defense statement was likely copied off of information Lycoming released, not fabricated out of thin air.  But what was the context of a NDA in order for Lycoming to test fuel?  I'm sure there's way more background on that we aren't privy to…and probably won’t be. 

[UteM20F]

Speaking of the defense statement, besides Hoyle, the other person quoted extensively is "D'Acosta", whose declaration was quoted 5 times.  This is likely Chris D'Acosta, the CEO of Swift fuels.  No one is more virulently anti-GAMI than he, which is understandable given that GAMI market share comes at his expense.  The entire defense to the lawsuit seems to be to bash G100UL.

[EricJ]

20 minutes ago, UteM20F said:

Speaking of the defense statement, besides Hoyle, the other person quoted extensively is "D'Acosta", whose declaration was quoted 5 times.  This is likely Chris D'Acosta, the CEO of Swift fuels.  No one is more virulently anti-GAMI than he, which is understandable given that GAMI market share comes at his expense.  The entire defense to the lawsuit seems to be to bash G100UL.

I read the document and it seemed much broader than that to me.   Since this is G100UL-related thread, those are the parts that are getting quoted here.

[Justin Schmidt]

3 hours ago, gabez said:

My mechanic has officially opened the tanks, drained the fuel and he is going through the plane. Hopefully by this Friday I will have a summary of what's going on

As I said, I will pay for a spectrograph of the fuel and paint chips around. This will be real scientific data

[gabez]

6 minutes ago, Justin Schmidt said:

As I said, I will pay for a spectrograph of the fuel and paint chips around. This will be real scientific data

happy to ship you paint chips and a sample of fuel (tho not sure how to do the latter) but def can do the former? pls dm your address

[Marc_B]

Not my video.  But second video release on YouTube.

[PT20J]

My position has always been that more testing was needed because we had one demonstration that showed paint damage and another that did not.

The second video shows more extensive testing and also highlights a difference in methodologies (test panels submerged vs. fuel allowed to evaporate on the surface). It is evident that there is paint damage in the test that allows evaporation on the surface and I agree that this more closely replicates in service conditions.

The effect on EZ Turn (aka Fuel Lube) is very concerning because the goo could clog carburetor and fuel servo components. 

[gabez]

42 minutes ago, PT20J said:

My position has always been that more testing was needed because we had one demonstration that showed paint damage and another that did not.

The second video shows more extensive testing and also highlights a difference in methodologies (test panels submerged vs. fuel allowed to evaporate on the surface). It is evident that there is paint damage in the test that allows evaporation on the surface and I agree that this more closely replicates in service conditions.

The effect on EZ Turn (aka Fuel Lube) is very concerning because the goo could clog carburetor and fuel servo components. 

I think we can all agree G100 will attack the paint and seals. There is too much world evidence in 60 days to think otherwise, the next step is it attacking the sealant also and if so is it moving downstream? The SJ FDSO has sent a crew to KWVI to go through the evidence of now 3 planes, all 3 planes cannot fly right now.

[Marc_B]

It's interesting that Mr. Braly has pointed towards towards Toluene and his initial posts here on MS made a point of pointing out up to 29% Toluene in 100LL.  I suspect typically higher overall levels of aromatic hydrocarbons in G100UL (up to 40% xylene).  However, there's allegations from other sources that it's the meta-toluidine component that's the issue.  Certainly meta-toluidine is an aggressive solvent, with a boiling point of 398.1F, and the evaporation rate is considered "negligible" at room temp meaning it evaporates very slowly.

Would be interesting to "test" a G100UL sample MINUS the meta-toluidine and see if it had the same effect on paint.  The composition of the "film" remaining on the surface after the more volatile components have evaporated would be very informative I think.  Both G100UL as well as 100LL have xylene and toluene (although in different amounts).

On 1/7/2025 at 9:56 AM, George Braly said:

I, personally,  have never seen G100UL strip aircraft paint which had been applied in a manner consistent with standard aircraft paint shop practices. 

On 1/7/2025 at 9:24 AM, George Braly said:

But that PAFI goal never included creating a replacement for 100LL that did not degrade "inexpensive" paint as 100LL often does, and has for fifty years.