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

[GeeBee]

40 minutes ago, Marc_B said:

Agreed.  If you look at the Aeronca Champ with paint damage, the paint is bubbled up, not just peeling or flaking off.  Same as the Mooney described in this thread, the Cessna 421C, as well as how it looks on the AOPA Baron.  If it was just attacking the primer you'd think it would just chip and peel rather than bubble and expand.

Is Beechcraft paint technique materially different than other manufacturers?  What coating/primer/paint/etc have they typically used?

A lot of manufacturers use self-etching primers then paint. I hate this method. Self-etching means, the crap that was on the aluminum (mostly aluminum oxide) but tooling grease etc is encapsulated within the primer. I have seen this on 
Cessna, and Piper lines. I have never observed Mooney's line but I know they contracted a lot of paint out to independent "line shops" which means the self etching primer process was used. I can tell you from personal observation that Beechcraft was one of the few manufacturers that etched, rinsed, alodine coated then primed the aluminum with non-etching primer (because it was etched before and the contaminate rinsed away. With the alodine coating you create a tremendously strong intermediary between the aluminum and the primer. With the entire process you have a methodology that creates a very strong coating system. The only thing you could do to improve that coating system is to use something like Epi-bond Epoxy primer which is something that is often used in corrosive areas like battery areas and lavatory areas. What Beechcraft uses these days now they are part of Textron and with the advent of low or no VOC paint I do not know. I suspect Textron paints all their airplanes the same with self etching primer.  I suspect those panels are old Beechcraft alodine method paint systems.

[EricJ]

30 minutes ago, ragedracer1977 said:

If this is indicative of their testing methodology in other areas, it's concerning.  And, to be frank, I'm a little concerned that it may be. 

GAMI's test of the Beech panels as "hard data" refuting multiple (and growing) cases of field failures suggests to me that GAMI either doesn't know how to do testing for field failures, doesn't want to do proper testing, doesn't care, or perhaps even wants to deliberately obfuscate the issues.   None of those possibilities inspire confidence in their responses or statements, and, as you mention erodes confidence in whatever testing they may have done previously. 

I can understand a small company with a large investment in a product being reluctant to do anything that doesn't promote it or put it in a positive light, especially when the process doesn't really allow them to make significant changes without having to start a lot of things over.  It does put the burden on the users, though, and I still hope the bad experiences in the field are limited to economic consequences rather than anything actually safety related.   Keeping my fingers crossed, but it might take some time for all of the materials issues to fully play out.

[redbaron1982]

53 minutes ago, EricJ said:

I can understand a small company with a large investment in a product being reluctant to do anything that doesn't promote it or put it in a positive light, especially when the process doesn't really allow them to make significant changes without having to start a lot of things over. 

You nailed it here. GAMI's future is at stake.

Edited January 16 by redbaron1982

[PT20J]

All the negativity probably ran @George Braly off of here (which would be too bad because I think we all need to keep open lines of communication until this is understood),but he’s continued to post on BT. He posted a drip-evaporate-drip test on one of his Beechcraft panels and said he will post a complete YouTube video of the test maybe later today. 

One interesting thing is that he was able to polish out the brown stains whereas others including @donkaye have been unable to do so. So, perhaps not all paint reacts the same to G100UL. Maybe the paint on George’s test panels is newer or something. I believe he said they were not original Beech paint.

 

[PT20J]

2 hours ago, philiplane said:

Beech, Piper, and Cessna use virtually identical paint systems. Cirrus does too. But in the aftermarket, anything goes and quality is anything but uniform. As I mentioned, it is more common than not, to find shops using a mix-match of materials in an effort to contain costs. Very few use the OEM procedures and materials. I've only seen one paint shop measure mil thickness of each step, and on the final finish coat on a light aircraft. That was a jet shop in Oklahoma, who did it in the same manner as their jet work. Many shops will use primers that will do exactly what you've seen in the photos when exposed to xylene or toluene. Again, the top coat is a victim of primer failure, not the other way around.

Would you expect this to happen with epoxy primer?

[philiplane]

1 hour ago, PT20J said:

Would you expect this to happen with epoxy primer?

The one-part epoxies commonly used in cheap shops are very sensitive to a variety of solvents. They're not much better than lacquer primers. 

[gabez]

1 hour ago, PT20J said:

All the negativity probably ran @George Braly off of here (which would be too bad because I think we all need to keep open lines of communication until this is understood),but he’s continued to post on BT. He posted a drip-evaporate-drip test on one of his Beechcraft panels and said he will post a complete YouTube video of the test maybe later today. 

One interesting thing is that he was able to polish out the brown stains whereas others including @donkaye have been unable to do so. So, perhaps not all paint reacts the same to G100UL. Maybe the paint on George’s test panels is newer or something. I believe he said they were not original Beech paint.

 

what did he polish it with? 

Edited January 16 by gabez

[George Braly]

On 1/14/2025 at 9:48 AM, ragedracer1977 said:

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

 

https://youtu.be/Q4MgLkTamP4

Documentation for the G100UL Avgas  drip-evaporate-drip-evaporate paint testing. 

 On a lighter note:  What you see is definitely a breach of the protocol for practicing good fuel hygiene!

[Marc_B]

@George Braly have you tested the fuel from the RHV and WVI aircraft of note and was their fuel confirmed to conform with G100UL?

What was standard shop technique for cleaning stains off and did those panels have surface prep/wax/ceramic?  How different is the staining with UV light than standard indoor lighting or infrared?

Have you tested any other paints, aircraft parts, or manufacturers than the louvered Beech panels?

[GeeBee]

1 hour ago, philiplane said:

The one-part epoxies commonly used in cheap shops are very sensitive to a variety of solvents. They're not much better than lacquer primers. 

Epi-bond is a two part epoxy primer. I have always wanted to paint a whole airplane with it. The problem is the masking would have to be perfect because there is no recovery from overspray.

[IvanP]

1 hour ago, George Braly said:

 

https://youtu.be/Q4MgLkTamP4

Documentation for the G100UL Avgas  drip-evaporate-drip-evaporate paint testing. 

 On a lighter note:  What you see is definitely a breach of the protocol for practicing good fuel hygiene!

The peeling paint at the edge in  right upper corner that we see in these images did not appear to be present in the early stages of the test. At 1:14 of the video there does not appear to be any damage to the the edge, again 2:17 - 2:38 - no visible damage to the edge, at 2:40 some damage is visible, and the fnal images show paint peeling from the edge. Maybe I am missing something here as there was no clear shot of the whole panel before the test.  

Edited January 17 by IvanP

[PT20J]

5 hours ago, GeeBee said:

A lot of manufacturers use self-etching primers then paint. I hate this method. Self-etching means, the crap that was on the aluminum (mostly aluminum oxide) but tooling grease etc is encapsulated within the primer. I have seen this on 
Cessna, and Piper lines. I have never observed Mooney's line but I know they contracted a lot of paint out to independent "line shops" which means the self etching primer process was used. I can tell you from personal observation that Beechcraft was one of the few manufacturers that etched, rinsed, alodine coated then primed the aluminum with non-etching primer (because it was etched before and the contaminate rinsed away. With the alodine coating you create a tremendously strong intermediary between the aluminum and the primer. With the entire process you have a methodology that creates a very strong coating system. The only thing you could do to improve that coating system is to use something like Epi-bond Epoxy primer which is something that is often used in corrosive areas like battery areas and lavatory areas. What Beechcraft uses these days now they are part of Textron and with the advent of low or no VOC paint I do not know. I suspect Textron paints all their airplanes the same with self etching primer.  I suspect those panels are old Beechcraft alodine method paint systems.

The Mooney M20J SMM says to use a wash primer -- which I believe is a self etching primer -- before applying an epoxy primer. So, I assume that's what the factory did. I've got a lot of paint chipping off the leading edges of all surfaces and various flat rivet heads that are not smoking (Interestingly, the paint is adhering well on a few rivets that are smoking). My paint guy says he sees that a lot on Mooneys.

I'm having it painted at Sunquest. They are highly rated and paint Caravans for FedEX and seaplanes for Kenmore Air among others. I'm beginning to understand why my paint job is going to cost north or $40K when others seem to get it done cheaper.

[A64Pilot]

Military aircraft, at least the AH-64 are or were painted with a two part epoxy primer, it’s not uncommon primer. We used it on repairs all the time

They were top coated with CARC paint “Chemical Agent Resistant Coating” I believe back in my day it was a two part Epoxy paint.

Thrush has always Alodined every piece of aluminum in big tanks approx 5 ft wide 8 ft deep and 30 something feet long, it was 5 or 6 tanks.

Beech used to alodine their aircraft not sure now, Cessna would alodine seaplanes but not land planes, I believe both may have just wash alodined, you really can’t do a good job without tanks. 

I used to build my own oil separators, the one one the left was run through the alodine tanks, brush or wash alodine doesn’t get near the same reaction. Sorry it’s the only pic I have of tank alodine parts.

I think the one on the right was wash alodined, but it’s been a long time so I don’t really remember

 

Edited January 17 by A64Pilot

[GeeBee]

12 minutes ago, PT20J said:

The Mooney M20J SMM says to use a wash primer -- which I believe is a self etching primer -- before applying an epoxy primer. So, I assume that's what the factory did. I've got a lot of paint chipping off the leading edges of all surfaces and various flat rivet heads that are not smoking (Interestingly, the paint is adhering well on a few rivets that are smoking). My paint guy says he sees that a lot on Mooneys.

I'm having it painted at Sunquest. They are highly rated and paint Caravans for FedEX and seaplanes for Kenmore Air among others. I'm beginning to understand why my paint job is going to cost north or $40K when others seem to get it done cheaper.

I find on Mooneys there is a great variability in paint origins and processes. Some are factory, some are contracted. Some using really good finishes, some are economy paint jobs.  You are correct, a good paint job costs a lot of money. It is one of the the few times, you really get what you pay.

[Justin Schmidt]

34 minutes ago, IvanP said:

The peeling paint at the edge in  right upper corner that we see in these images did not appear to be present in the early stages of the test. At 1:14 of the video there does not appear to be any damage to the the edge, again 2:17 - 2:38 - no visible damage to the edge, at 2:40 some damage is visible, and the fnal images show paint peeling from the edge. Maybe I am missing something here as there was no clear shot of the whole panel before the test.  

You can see it at start of the stop action 

[Schllc]

58 minutes ago, GeeBee said:

I find on Mooneys there is a great variability in paint origins and processes. Some are factory, some are contracted. Some using really good finishes, some are economy paint jobs.  You are correct, a good paint job costs a lot of money. It is one of the the few times, you really get what you pay.

I will second this for sure. My plane had really bad quality paint job. I cannot say if it was poor workmanship or pool quality materials.  If the previous owner had any influence it would have been put on with a roller. It’s aging strangely, lots of failures at places it’s obviously difficult to prep properly. 
I intend to have a written specification from the paint manufacturer, and I hope Gami will opine on their thoughts to which would tolerate the fuel best. 
good-fast-cheap, pick two

[donkaye]

6 hours ago, George Braly said:

 

https://youtu.be/Q4MgLkTamP4

Documentation for the G100UL Avgas  drip-evaporate-drip-evaporate paint testing. 

 On a lighter note:  What you see is definitely a breach of the protocol for practicing good fuel hygiene!

George, What polish did you use?

[gabez]

13 hours ago, George Braly said:

 

https://youtu.be/Q4MgLkTamP4

Documentation for the G100UL Avgas  drip-evaporate-drip-evaporate paint testing. 

 On a lighter note:  What you see is definitely a breach of the protocol for practicing good fuel hygiene!

What do you make of the planes who had paint damage? As in the paint was stripped off

[philiplane]

I use the 3M Perfect-It series polish to remove fuel stains and restore paint to like-new. I also use it on existing paint that will be spot-repaired and blended. You want the existing paint as clean as possible before blending in a repaired area. 

https://www.3m.com/3M/en_US/collision-repair-us/featured-products/random-orbital-polishing-system/?utm_term=sibg-aad-na-en_us-lead-g_a_o_rops-cpc-google-pfx-na-brand-jan24-na&gad_source=1&gbraid=0AAAAACgp1ZoT1QO_SfSoRHwwEF5c4yYqb&gclid=CjwKCAiAnKi8BhB0EiwA58DA4bNR8OyTSgQLl5z2I1sm98ijyxyWFp8zvrnJRqER0Cc4Pamb15mFoRoCx0cQAvD_BwE

Most shops don't use this because it's not cheap. A kit with all three polishes and the corresponding buffing wheels is about $300. But nothing works better.

[Pinecone]

On 1/14/2025 at 4:12 PM, MikeOH said:

4) Can anyone buy meta-toluidine?  It would be interesting to test paint exposed only to that chemical.  (As would, as suggested by  G100UL absent meta-toluidine)

 

https://www.sigmaaldrich.com/US/en/product/aldrich/511218?srsltid=AfmBOooEjKYeQ-06IBqwXcccf2X_aiRUOwEAgewQLK9TXK7ii1Vuzc5T

$164 per liter.

Not sure how you would get G100UL without any, as the formula is not published.

[Pinecone]

On 1/14/2025 at 6:23 PM, PT20J said:

I wouldn’t read too much into those percentage ranges. Most likely, the amount of each component is much more tightly controlled. Companies blur the ranges intentionally to avoid disclosing the formula which is a trade secret.

THIS ^^^^^^

And SDSs are written by lawyers these days.  

[Pinecone]

On 1/15/2025 at 9:49 AM, philiplane said:

For what it's worth, fuels are not tested to be compatible with paint. They're not expected to be routinely applied to painted surfaces. 

As for rubber components in the fuel storage and distribution system, it seems obvious that more testing is needed to identify and develop solutions to any potential G100UL compatibility issues.

Fuels ARE required to be tested to be compatible with things like seals and O-rings.  And G100UL was tested against actual seals and O-rings in actual aircraft systems such a valves and selectors and fuel injection systems.

And, AFAIK, there have been ZERO field reports of issues with them

[Pinecone]

On 1/15/2025 at 7:22 PM, A64Pilot said:

What I am saying is that if you remove the lead, yes you can most certainly run PAO but it shouldn’t significantly increase your oil change interval, because we, very much like Diesels don’t change oil because it’s worn out, changing viscosity or the additive packages breaking down, we change oil to get the carbon etc out, carbon as I’m sure you know is very abrasive. Diesels trash their oil with soot, especially newer ones with EGR

Except that Lycoming has already published a Service Bulletin that doubles the oil change interval when using unleaded fuels.

I think that double the oil change interval is a significant increase.

And once 100LL is gone, synthetic oils will further increase oil change intervals, as they did in auto.  We went from 3000 mile oil changer intervals to over 15,000 miles.

[MikeOH]

1 hour ago, Pinecone said:

Except that Lycoming has already published a Service Bulletin that doubles the oil change interval when using unleaded fuels.

I think that double the oil change interval is a significant increase.

And once 100LL is gone, synthetic oils will further increase oil change intervals, as they did in auto.  We went from 3000 mile oil changer intervals to over 15,000 miles.

Can you cite the new Lycoming SB?  The old one required a 4 month change interval such that doubling the change hours was pointless for most owners (>150 hours/year).  Of course, Lycoming has NOT approved G100UL so a bit moot at this point.

[Schllc]

@George Braly

are you able to detail the specifics about the “sample” fleet of aircraft used for testing?

I know embry riddle was one source, but if it was tested on 10 identical 172’s, that result will likely be different than 10 random planes of different ages and manufacturers. 
at this juncture, I think it would be unrealistic to say the results would be the same. 
Once this fuel is being used by a broad range of aircraft, over time, we will see if there are any real issues. I suspect any that arise will be manageable, but knowing what to expect is both fair and safe. 
Paint damage, while certainly not cheap, is not likely an airworthy issue, but bladders, tank sealant, and engine/fuel hoses, seals and o-rings, most certainly are, and I assumed that this is an issue your company would want to fully vet.
It would appear that it’s time for more extensive testing, instead of a fleet wide mandate, and to be fair, you have said many times you are not asking for the abolition of 100LL immediately.

Its obvious there are many people more than willing to use your fuel exclusively, that seems to be a ripe crop of volunteers with a broad range of conditions and aircraft to follow and monitor. 
 

I personally would be more than happy to use the fuel if your company helps identify the proper paint spec, and determines it will not affect my tank sealant.