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

[Pinecone]

7 hours ago, Marc_B said:

I would definitely not use that descriptor.  It's an incredibly small number of planes in the fleet that have used G100UL in total and it's yet to be determined if they've "not had any issues."  Additionally, ~300-400 gallons per month is a tiny amount of the fuel sales in the area.

Something over 100 airplanes have used it.  Some 7 or so have issues.

So that means more than 90 without issues.  You just don't hear from them

[MikeOH]

25 minutes ago, Pinecone said:

Something over 100 airplanes have used it.  Some 7 or so have issues.

So that means more than 90 without issues.  You just don't hear from them

So, after a VERY short time in the field we have a 7% (70,000 ppm) issue!  That troubles me greatly.  YMMV, I guess

[gabez]

1 hour ago, Pinecone said:

Something over 100 airplanes have used it.  Some 7 or so have issues.

So that means more than 90 without issues.  You just don't hear from them

actually that is not the entire picture. there are more than 7 planes that Mike has collected data on and it is his story to tell. 

I personally know of 1 mooney who filled up the tanks and the owner asked my mechanic to dump the fuel out as soon as he saw my plane in the shop. 
There is also a piper owned by a CFII on the field who used G100UL and stopped as soon as it stained the wings. 

There is also a 140 that had a problem with the primer and went in with a rough running engine on G100UL. 

None of this 3 are in the 7. 

So all of it to say, the data presented is questionable

[IvanP]

10 hours ago, Pinecone said:

There are a large number of planes that have not had any issues, so are likely using the fuel.

Just curious how many planes is "a large number" here if the fuel is only sold at 2 airports and in rather modest quantities. 

[Pinecone]

A hard room.

A larger number than have had issues.   People are talking like 75% or more are having issues.

Dumping the tanks due to OTHER airplanes having issues is not a data point.  I would also question a primer issue on a 70 year old airplane without seeing the logs.  It could be the original O-ring.

Wing staining on the top is not a major issue.  Not desirable, but not in the small ballpark as some of the leaks and major paint damage.

[Marc_B]

The problem is that according to GAMI there are NO issues.  Everything seen was either "due to 100 low lead" or due to "inadequate construction and maintenance."  Braly won't deny any of the findings in any of the Luvara videos, and admits that he doesn't feel they were tampered. Braly posts, "I do not accuse the sponsor of fabricating the results.  I do dispute the significance of the results as applied to the real world."

So we're at an impasse.  You either feel that the aircraft having issues may be similar to your aircraft or you believe that "G100UL is a 100% drop in fuel without modification and invisible to the the pilot and the aircraft."

The biggest problem with this, is that GAMI won't openly release what was tested or how they tested it.  Their "hard data" released to the public/potential users is a series of garage YouTube videos that due to their methods are impossible to replicate even by them.

The STC process is being left up to the owner and A&P/IA applying the STC to determine if this is safe and appropriate for your airframe IN ITS CURRENT STATE.  GAMI denies any issue, but doesn't deny pointed testing showing detrimental effects and mirroring the issues currently being seen in the field...  On one hand GAMI says "you don't need to change anything, it's 100% drop in" but when you run into issues GAMI says "oh you had substandard maintenance because the industry uses Viton materials and teflon lined hoses."  Only the industry still has nitrile and Buna-N pervasive throughout the fleet and even in new products!  So at the end of the day it's buyer beware.  You might have issues and if you do it's going to be very costly to fix, and you're unlikely to get any support from GAMI (in the absence of legal action).

My question for people with a view similar to @Pinecone, is how many problems should be required to admit there is an issue that needs to be addressed?  Is the threshold a crash or fatality?  Or would that still be due to "inadequate construction' and "poor maintenance"?

 

This has devolved in a circular argument of talking past either other, and taking data points of field use and claiming these are all poorly maintained aircraft that are old and have had such a corrosive life with 100LL that's causing all the issues (despite not posting any proof that this was actually the case). With the comments from Braly online and with his Consent Decree Declaration, I don't think you're going to see any "hard data" coming from GAMI.  But I suspect that you'll continue to hear that "it's all due to 100LL" and our "inadequate" Mooneys...and for me that just doesn't ring true.  I'd really love to see G100UL go though the PAFI/EAGLE process.

[IvanP]

4 hours ago, Pinecone said:

A hard room.

A larger number than have had issues.   People are talking like 75% or more are having issues.

Dumping the tanks due to OTHER airplanes having issues is not a data point.  I would also question a primer issue on a 70 year old airplane without seeing the logs.  It could be the original O-ring.

Wing staining on the top is not a major issue.  Not desirable, but not in the small ballpark as some of the leaks and major paint damage.

I guess that will be matter of opinion then. For some people 100 may be a large number, for some it may not. I think when aircraft safety is concerned any factor that causes 7-10% of aircraft in the fleet to experience problems is significant.  

Regardless of what part of the plane is incompatible with the new fuel, the fact remains that G100UL is not what the current GAMI narrative is pushing, i.e., drop-in replacement for 100LL that is safe for use across the entire piston fleet. 

Personally, I could not care less if FBOs decide to sell the stuff and potentially expose themselves to product liability suits so long as there is a choice for pilots no to buy it. GAMI is pushing for government mandate that will eliminate the choice. Just curious about couple of points:

1. What is the potential liability for the A&P who "installed" teh STC on an aircraft that is subsequently rendered unairworthy as a result of material incompatibility.

2. How many of the vocal advocates for the G100UL actually put it in their own planes? Put your money where your mouth, or keyboard, is and take a chance on this marvel of modern chemistry that will save us from doom caused by the minuscule amount of lead in 100LL but is shrouded in secrecy about testing.

Edited Tuesday at 04:35 PM by IvanP

[gabez]

https://www.aopa.org/news-and-media/all-news/2025/march/25/faa-rules-avgas-ban-violated-grant-assurances

 

[toto]

3 minutes ago, gabez said:

https://www.aopa.org/news-and-media/all-news/2025/march/25/faa-rules-avgas-ban-violated-grant-assurances

 

I need to buy some more popcorn

[redbaron1982]

11 minutes ago, gabez said:

https://www.aopa.org/news-and-media/all-news/2025/march/25/faa-rules-avgas-ban-violated-grant-assurances

 

I guess they are trying to kill G100UL without saying that they made a mistake in approving the STC... if 100LL is not banned, G100UL is death.

[gabez]

5 minutes ago, redbaron1982 said:

I guess they are trying to kill G100UL without saying that they made a mistake in approving the STC... if 100LL is not banned, G100UL is death.

that is a very interesting prospective 

[76Srat]

31 minutes ago, redbaron1982 said:

I guess they are trying to kill G100UL without saying that they made a mistake in approving the STC... if 100LL is not banned, G100UL is death.

Indeed yours is an interesting perspective, but what the ruling actually clarifies isn't the leaded versus unleaded avgas issue--it was a clear and unequivocal ruling that agencies (in this case, a county) cannot unduly deprive rightful access to something federally mandated otherwise.  It just so happens that this case involves 100LL and 100UL of various types (such as they are).  Unfortunately, all of aviation is on a downhill slide on this issue and literally every other issue taken up by those opposed to anyone exercising their freedom to fly.  

If we're truly supportive of GA overall, and I believe all of us on here are, then we need to come together and let the market bear out what should or shouldn't be available.  To do anything less than that is to remain unwilling subjects to bureaucrats who truly do not have GA's best interests in mind.  In fact, they have the opposite in mind:  absolute abolishment.  

If all we do is sit back and expect to turn our heads and cough when told, then we shouldn't even expect a soft, gentle hand when asked to do so.

 

 

[mluvara]

49 minutes ago, redbaron1982 said:

I guess they are trying to kill G100UL without saying that they made a mistake in approving the STC... if 100LL is not banned, G100UL is death.

This ruling is about upholding existing rules and regulations and the situation goes back over three years. Those of us who require 100 octane have suffered since the draconian ban went into effect on Jan 1,2022. Then the County finally brought G100UL in last Nov after promising for three years that it was 'coming soon'.

Note: I am a complainant in the Part 16 complaint and people have misattributed my motives in the situation.

Edited Tuesday at 08:16 PM by mluvara

[IvanP]

1 hour ago, gabez said:

https://www.aopa.org/news-and-media/all-news/2025/march/25/faa-rules-avgas-ban-violated-grant-assurances

 

Good ruling, but it does not address the CA statewide ban that is looming in the very near future. We shall see what the judge in the CEH suit will say.  

[MikeOH]

While the ruling is encouraging, the possibility exists that Santa Clara County doesn’t care! As evidenced by the mention that the County had NOT applied for any Federal grants in some time; they don’t want to be obligated.
They might just pay back the 6.8 million of existing grants and tell the FAA to get lost!

[philiplane]

On 2/25/2025 at 7:42 PM, Marc_B said:

Sounds like the California Consent Judgment case has been continued to Feb 27.  But I read part of the information including Mr. Braly's declaration in support of the motion to enforce the consent judgement.  I'm not sure what to make of his comments that the Mooney aircraft have a unique and inadequate type of fuel tank construction.  He offers that sealant in those tanks will only last about 15-20 years before they are at imminent risk of leakage and need to be resealed.  He suggests that leaks are due to the inadequate design and manufacturing methods used to produce these aircraft.  He suggests that the problem has been so significant that STCs were developed for fuel bladders to correct the issue.

 

I'm curious why these tanks have been so successful over the years and can routinely last 25 years plus (plenty over 40 years) and this is "inadequate"??  Plenty of engines, hoses, alternators, starters, avionics, vacuum pumps, etc. often last WAY less.  What am I missing here other than it's very likely that GAMI may feel that G100UL is incompatible with Mooney?

 

The polysulfide sealants used in all wet wing applications have a finite life. They last longer in tanks that contain jet fuel. Most tanks that contain jet fuel also have stronger structure that does not flex like a Mooney wing does. Aviation gasoline is as much of a solvent as it is a fuel though, and it's not expected for wet wings to last more than 20 years. Braly is not wrong here. 

[201Steve]

1 hour ago, MikeOH said:

They might just pay back the 6.8 million of existing grants and tell the FAA to get lost!

Or they don’t pay anything back. That’s another lawsuit over many years that would kick the can down the road. 

[IvanP]

1 hour ago, MikeOH said:

While the ruling is encouraging, the possibility exists that Santa Clara County doesn’t care! As evidenced by the mention that the County had NOT applied for any Federal grants in some time; they don’t want to be obligated.
They might just pay back the 6.8 million of existing grants and tell the FAA to get lost!

Or thay can do what Dick Daley did with Meigs Field in Chicago. That was, in my not so humble opinion, the ultimate "dick" move in complete disregard for safety of the aircraft based on the field. It would not surprise me if something like that would happen in CA.    

[GeeBee]

1 hour ago, philiplane said:

The polysulfide sealants used in all wet wing applications have a finite life. They last longer in tanks that contain jet fuel. Most tanks that contain jet fuel also have stronger structure that does not flex like a Mooney wing does. Aviation gasoline is as much of a solvent as it is a fuel though, and it's not expected for wet wings to last more than 20 years. Braly is not wrong here. 

You apparently have never watched an A330/A350 wing in flight

[philiplane]

20 minutes ago, GeeBee said:

You apparently have never watched an A330/A350 wing in flight

I've watched the A340 wing in flight, but a 787 is even more flexible. The tips rise several feet on takeoff.  

 

Edited yesterday at 02:36 AM by philiplane

[PT20J]

Ever watch the engines on a 747 wing flying in loose formation in heavy turbulence. Now that’s scary!

[MikeOH]

2 hours ago, 201Steve said:

Or they don’t pay anything back. That’s another lawsuit over many years that would kick the can down the road. 

Good point!

[MikeOH]

2 hours ago, IvanP said:

Or thay can do what Dick Daley did with Meigs Field in Chicago. That was, in my not so humble opinion, the ultimate "dick" move in complete disregard for safety of the aircraft based on the field. It would not surprise me if something like that would happen in CA.    

UGH!  I hadn't thought about that possibility.  I'm sure the vulture land developers would be happy to 'loan' out their bulldozers

[GeeBee]

9 hours ago, philiplane said:

I've watched the A340 wing in flight, but a 787 is even more flexible. The tips rise several feet on takeoff.  

 

Actually an A330/A350 wing rises above the top of the fuselage in flight. Equally so A330/A340/A350 have "active load alleviation" in that if the wings are over loaded the speed brakes pop out and unload the wing. Then of course there is the ultimate test, going 15 meters above the fuselage.

 

[A64Pilot]

It was fairly obvious to me that this fuel was a safety concern from just what it did to O-rings, that was enough for me, the paint issues came along and that again screamed it was an aggressive solvent, I’m not talking about staining I’m talking about dissolving Jet-Glo. I wasn’t surprised at all when it ate fuel tank sealer, I expected that after the paint problems. Paint I see as the canary in the coal mine. I think in time we will see fuel pump leaks, maybe fuel servo problems and or fuel spider problems, anything in the fuel system that has “rubber” components. Maybe even fuel hoses.

Then as it became apparent that “fresh” fuel wasn’t as big a problem as was what was left behind when the more volatile fluids flashed off made sense as assumption that only the fresh fuel was tested during the STC process. I can accept that as an honest mistake. But you need to own up to your mistakes, mistakes don’t get better with time.

1 in 1000 problems is unacceptable, 7 out of 100 is crazy, especially how quick the problems popped up, I’m used to mistakes only showing up months or years later, not within days. Over time that 7 out of 100 will increase I’m sure.

I’m amazed it hasn’t been voluntarily withdrawn, will it take a fatality for that to happen? Do they think these issues are made up, that they don’t exist, or do they think they will just go away on their own?

I guess I expect that in time the FAA will pull the STC

Edited 10 hours ago by A64Pilot