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

[201Mooniac]

3 hours ago, MikeOH said:

I have received several DMs indicating that Paul Millner is a petroleum engineer that helped Braly develop G100UL.  I have NO idea if this is true; I have not verified that in any way.

If true, however, it would explain his court declaration.  I would hope the court (i.e. the judge) is aware of his position, but maybe not

Paul is a retired petroleum engineer but as I understand it he did not work with GAMI on the fuel but instead he worked with the FAA on PAFI (might have been in his work capacity) and with AOPA on their advocacy for unleaded fuel.

[gabez]

so I put some fuel into a container...by now means this is scientific, I put about 5-6oz left it open in the garage, 1. there is still some liquid 4 days later ...2 . what's the black stuff behind? Mike L had the same black stuff in his videos. 

[redbaron1982]

On 2/25/2025 at 8:12 PM, ragedracer1977 said:

Your planes are pieces of junk.  Paraphrased.

 

 

Do anyone know what Mr Braly refers to when he said "a unique and inadequate" type of fuel tank?

I guess he is not referring just to the wet wing concept, right? There are a lot of airplanes with wet wings, most airliners uses wet wings, Cirrus does too.

I mean, if he is referring only to the wet wing concept, someone could argue that Mr Braly's statement is false testimony, no? What's unique about a design that all airliners use and also one of the most successful modern GA manufacturer, like Cirrus.

[Marc_B]

10 minutes ago, redbaron1982 said:

Do anyone know what Mr Braly refers to when he said "a unique and inadequate" type of fuel tank?

I tried asking this from the person Braly quoted here (Del Lehmann) that he referenced.  All I got was a sarcastic commentary comparing my intelligence to his dog (who he thinks is smarter).

It was a rude answer for a sincere question...seems this is the case more and more frequently pertaining to this fuel.  I'm not sure what the "adequate" method of fuel tank other than apparently one that doesn't have issues with G100UL?

[Deb]

Del Lehmann posted this on BeechTalk (https://www.beechtalk.com/forums/viewtopic.php?f=7&t=234904&start=645):

I do not generally take in fuel leaks as a stand-alone job, but I have repaired many Mooney wings due to bird/animal strikes, hail damage, ramp rash.....maybe 15-20 wings over 30 years. Every integral fuel tank skin that we have drilled off lacked faying surface sealant between the internal structure (ribs, stringers) and the skin. It's obvious they were assembled dry, then buttered up the seams and rivet butts by working through the access holes. This is unique among the big four (I've seen some early Piper tanks like this, but rare). Cessna and Beech all have faying surface sealant.

I've heard that Mooney did try assembling the tanks wet for a period of time and then went back to dry. If they were actually shooting the rivets with wet faying sealant, that wouldn't have helped. The riveting (hammering) action will displace the sealant. The wet sealant also acts as a lubricant between the bucking bar and rivet, causing an improper upset we call "elephant foot". The rivet bucktail sets before the shank swells tight. This is worse than shooting together dry.

The best way is to apply the faying sealant, then put a Cleco in every hole (Cleco is a temporary fastener. Need lots of Clecos). Then once the sealant is cured you can shoot the solid rivets. The faying sealant also acts as an adhesive between the skin and structure and inhibits movement. Now, the only potential leaks are the rivet butts, so all one has to do is butter the butts, leak test and good to go for decades. That's not what Mooney did.

[Pinecone]

22 hours ago, MikeOH said:

I have received several DMs indicating that Paul Millner is a petroleum engineer that helped Braly develop G100UL.  I have NO idea if this is true; I have not verified that in any way.

If true, however, it would explain his court declaration.  I would hope the court (i.e. the judge) is aware of his position, but maybe not

Paul was (now retired) petroleum engineer.  And a pilot who owns a Cardinal RG and is very active in the C-177 world.

He knows and talks with George, but was not directly involved in developing the fuel.  Or more importantly is not a financial partner in G100UL.

[IvanP]

1 hour ago, Pinecone said:

Paul was (now retired) petroleum engineer.  And a pilot who owns a Cardinal RG and is very active in the C-177 world.

He knows and talks with George, but was not directly involved in developing the fuel.  Or more importantly is not a financial partner in G100UL.

I am curious about what fuel does he put in his Cardinal since he appears to be a great supporter of G100UL. 

[A64Pilot]

I had a whole response typed but decided to delete it.

It’s pretty simple really, if the average Mooney is flying around with decades old wings that don’t leak, but upon putting in a new fuel they start leaking, it’s a pretty tough case to try to make that the fuel isn’t at least a contributing factor.

Fuel leaks are an airworthiness issue unquestionably.

Several aircraft reporting fuel leaks after beginning use of the fuel is in anyone’s opinion logically enough reason to suspend the sale of the fuel, but the real serious issue in my little mind is Cirrus being concerned that it has affected wing structure. I can’t imagine a worse scenario for a fuel than that.

Even if it were only Mooney’s that started leaking, I don’t have personal knowledge but have heard of Beech, Cessna, and Cirrus aircraft leaking. Oh, and an RV Homebuilt

I’m astonished the FAA hasn’t pulled the plug because of safety concerns

I can only think there are two possibilities.

1. G100UL is causing fuel leaks and in the Cirrus may have caused structural damage

2. The fuel is fine, nothing wrong and there is a Conspiracy to include Cirrus that is slandering the fuel.

I can’t think of a third. Is there one?

 

Edited Thursday at 07:51 PM by A64Pilot

[Schllc]

When I spoke to George, he was convinced that it was the dry assembly of the ribs to skin in the fuel tank areas that were the “deficiency”. 
in our conversation he said he worked in the Aerostar factory assembling the planes in the late 60’s and early 70’s. He said they wet those parts prior to assembly. 
I own an Aerostar too, and week “seeps” and repairs are a pretty regular item on these aircraft as well. This in spite of them being assembled “correctly”.  It is a fleet that is at least 20x smaller so I do t have any data to compare, but from talking to other owners and my experience over three years now, those tanks leak and need repair as well. 
At this juncture, t’s pretty difficult to believe that the fuel is not the problem here. 
it seems that resisting the obvious and inevitable is going to cause a lot more damage than pulling back a bit to reevaluate. 
Attacking an entire fleet on the scant evidence he is claiming seems to be a stretch at best. 

[slowflyin]

It seems reasonable to hypothesize a more aggressive fuel may be fine for freshly sealed tanks but would cause old, weak sealant to fail.   MY Bravo never leaked a drop until I had the paint stripped.  After inspection, Eddy advised the sealant was susceptible due to it's age.   I'm more concerned about the paint damage.  Most AC will leak sometime.  Big difference in resealing a 30 year old tank with unknown life expectancy prior to G100UL and resealing and repainting.  Alibi, I'm not wading off into the "drop in replacement" waters.  I understand the position.    

[EricJ]

15 minutes ago, Schllc said:

Attacking an entire fleet on the scant evidence he is claiming seems to be a stretch at best. 

It appears that throwing the Mooney fleet under the bus and ignoring the other aircraft that have been damaged is considered appropriate for some reason.    He cites that Cirrus, Continental, and Lycoming have all blessed G100UL, but we know that they have also formally published that G100UL is not approved in their products, and so have Cessna and Beechcraft.

He also states that during the approval process for G100UL he acted as their own DER, which may explain not only the apparent lack of sufficient testing but the opacity of the "results".   I'm reminded of how Boeing ultimately got into trouble doing their own approvals.   It's also becoming more evident why the OEMs keep citing preferring the collaborative standard processes compared to STC approval.

[ragedracer1977]

Personally I think the leaks are a bs avoidance tactic. EVERY SINGLE AIRPLANE on the planet will at one time or another, leak.  It just happens.  Could G100UL be advancing that?  Sure it could, probably is, even.

 But… I don’t care.  Up until now, a fuel spill or leak just gave you an opportunity to get your rag wet with fuel and clean some oil off the belly.  Now?  You have to repaint your plane if a lineman is sloppy.

 And we haven’t even talked about the rubber issues…

[MikeOH]

1 hour ago, A64Pilot said:

I can only think there are two possibilities.

1. G100UL is causing fuel leaks and in the Cirrus may have caused structural damage

2. The fuel is fine, nothing wrong and there is a Conspiracy to include Cirrus that is slandering the fuel.

I can’t think of a third. Is there one?

 

Here ya go:

3) FAA 'broke the mold' with a fleet-wide STC approval WITHOUT demanding sufficient testing.  And the only thing worse than a safety issue is egg on their face...they're 'looking the other way' at the moment.

[gabez]

the fact that several aircrafts, at least 8...I heard up to 20. have had issues and the common denominator is G100UL, it means there is something there....at the very least several sources including JP has said this fuel contains a lot of aromatic and it's hard on paint. "There are components that react w/UV and can stain the paint"....not my worlds. 

So putting tanks aside, you are left dealing with damaged paint unless you are there to promptly wipe it off....the lack of transparency is the reason we are here. no-one will convince me otherwise 

[redbaron1982]

6 minutes ago, gabez said:

So putting tanks aside, you are left dealing with damaged paint unless you are there to promptly wipe it off....the lack of transparency is the reason we are here. no-one will convince me otherwise 

I have always found the "refueling hygiene" process that GAMI has put out quite funny. And they kind of saying in a way as "hey, this is what everyone should be doing already"...

What a concept! Lol.

Maybe I'm not doing it correctly, but I don't do anything apart from trying not to spill fuel over the paint. If I spill some, I don't do anything; it just dries in the paint, and the next time I clean the airplane, I take care of it. I've never had any issues.

The GAMI process involves using an absorbent rag, with specific instructions not to wipe (underlined!) but instead let the rag absorb the fuel, clean the surface with an "approved" window cleaner, etc

[gabez]

20 minutes ago, redbaron1982 said:

I have always found the "refueling hygiene" process that GAMI has put out quite funny. And they kind of saying in a way as "hey, this is what everyone should be doing already"...

What a concept! Lol.

Maybe I'm not doing it correctly, but I don't do anything apart from trying not to spill fuel over the paint. If I spill some, I don't do anything; it just dries in the paint, and the next time I clean the airplane, I take care of it. I've never had any issues.

The GAMI process involves using an absorbent rag, with specific instructions not to wipe (underlined!) but instead let the rag absorb the fuel, clean the surface with an "approved" window cleaner, etc

totally....and if you do have a leak....that you may not see....then forget it.....also, the stains around the drain valves are bad. basically those spots are bound to be brown.

 

On the upside, I just had my engine data analyzed by Savvy. All looked normal during and post G1. I did not do their profile and we only had 4 data points w/G1. 

Cruise settings: 31MP, 2500 RPM 125 ROP (TIT) 13.1-13.3 FF

Temps with G1 a higher but from what Savvy has told me it is to be expected as the fuel has higher energy density for volume, so they would expect to see more temperature for the same FF settings. I am sure I am opening a can of worms here but just passing data as it was given to me. 

[IvanP]

2 hours ago, MikeOH said:

Here ya go:

3) FAA 'broke the mold' with a fleet-wide STC approval WITHOUT demanding sufficient testing.  And the only thing worse than a safety issue is egg on their face...they're 'looking the other way' at the moment.

It would be a rare occurrence for government bureaucrats to admit that they screwed up. 

[MikeOH]

25 minutes ago, IvanP said:

It would be a rare occurrence for government bureaucrats to admit that they screwed up. 

EXACTLY!

And, absent an 'incident', they can maintain plausible deniability.  When something happens later then they can 'swing into action', issue an emergency AD, and say, "See, we're responsive" to a safety problem.

[redbaron1982]

1 minute ago, MikeOH said:

EXACTLY!

And, absent an 'incident', they can maintain plausible deniability.  When something happens later then they can 'swing into action', issue an emergency AD, and say, "See, we're responsive" to a safety problem.

If the AD happens only after 100LL was banned and all distributors switched to G100UL, then we are going to be screwed and we will have to pay for whatever corrective action comes from the AD.

[MikeOH]

It looks like the hearing in the CEH case was held today, but the court's website doesn't have the document available yet.  So, no idea what happened.

Anyone know?

 

[A64Pilot]

54 minutes ago, IvanP said:

It would be a rare occurrence for government bureaucrats to admit that they screwed up. 

They will have to, the longer they wait the worse it will get, then when they take action it’s always to overreact as in unlikely I think that we will see any more fuel approval STC’s.

If G100UL is a problem and I believe it is, but I don’t have any hard data, but if it is the longer it’s sold the worse the problem will get.

Sure it will “eat” the sealant in the old tanks first, those that may have been close to leaking anyway. There have been examinations of wet wing tanks that have had G100UL in them and the sealant was noticeable softened so much so that moderate pressure from the borescope left depressions. I believe given enough time that it would fail even newer sealant.

They as in Gami know this I think and are hanging their hat on the theory that the components that are not in contact with the fuel will retain integrity, that was their explanation on O-rings anyway.

The fact that there have been so many leaks so fast seems in my opinion to indicate that there is a problem that will get worse.

But it does make one wonder why the Embry Riddle fleet didn’t have problems? How long as in months did they burn the fuel? My 2C was the whole interest was on the engines, nobody looked at the airframe, they were too absorbed on engines.

I was in the middle of Certification of an aircraft when Gulfstream crashed their G-650. You want find this anywhere I don't think but FAA headquarters blamed Atl ACO for inadequate supervision, (internally).

https://flightsafety.org/asw-article/fatal-flight-test/

Slowed us way down, we had to repeat some tests and others added to the Cert program just to make sure all blocks were checked.

So when the FAA reacts. I expect them to over react.

Oh, and another thing you wont see in writing is that the FAA was given a date by Political leaders that the G-650 WILL be certified by. Gulfstream had serious Political pull.

Edited Friday at 12:54 AM by A64Pilot

[toto]

3 hours ago, MikeOH said:

Here ya go:

3) FAA 'broke the mold' with a fleet-wide STC approval WITHOUT demanding sufficient testing.  And the only thing worse than a safety issue is egg on their face...they're 'looking the other way' at the moment.

 

[A64Pilot]

I suspect there will be Lawsuits, but also strongly suspect that there are no assets to get, that the principals are well covered.

A few Mooney’s may have to get reseals, but a Cirrus may need new wings?

I hope there will be no AD of it there is it will be limited to inspections

[Kelpro999]

Putting external leaks aside, while I was testing paint removers for a less expensive more readily available alternative than polygon which there is none, I did find that many would soften and release the red top coat (air dried buna-n). Not so much the polysulfide sealant. This is most concerning as thin sheets of top coating will wrap the pickup tube screens. 
 I would like to test 100ul on an original sealed access panel. Eventually will if I find some fuel.

[Marc_B]

29 minutes ago, MikeOH said:

So, no idea what happened.

continued to 3/5/25 at 9:30a local