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

[Z W]

I'd also decided not to post any more because of the negativity and hostility, but here's one more try.

If George and GAMI were just out to make money, there are far easier ways than G100UL. It seems to me they've gambled a huge amount of money over many years on a very risky project that just might keep all our old airplanes flying when they otherwise could have been grounded.

This website is a great resource, but it bothers me when vendors come here and get viciously attacked by a few vocal members. Some members pretty much ran the EarthX people out of here after they posted about the STC for their new product for the old Mooney fleet. This thread feels the same. We could do better.

[gabez]

7 hours ago, donkaye said:

I wasn't going to post to this thread anymore because of its negativity, but I've decided to post one more time.

George, I wouldn't respond anymore to those who are sure you're in it only for the money and are out to try to cause G100UL to fail whether deliberately or other reasons.  Having the determination to get FAA approval over a period of 12 years show an interest that's not only financial, but for the general betterment of General Aviation in my opinion.

Without trying to be arrogant, i've seen this mentality before when I was an Electrical Engineer.  I got interested in Real Estate and buying homes in particular.  After a few years and seeing the benefits of buying rental homes, I suggested to others in my engineering circle that they should consider doing the same.  The pushback was immense and I just stopped talking about it.

Fast forward 50 years and everything I tried to relate to my cohorts have come true for me.  I have no idea how my other engineering friends are handling their later years, but for me, I have been able to devote my time in service to others by flight instructing full time, and I have't had to work for anyone since 1974.

While a real estate program from technical standpoint is not on the same level as bringing an aviation fuel to market, it does prove that it's not always wise to listen to the naysayers.

Outside of the staining issue there may be other issues that develop over time.  I'll deal with them as they may develop.  Meanwhile, I won't shy away from using G100UL.

what if the issue will mean a dead stick and killing innocent people....how will you deal with it? your statement is quite shortsighted. you should not take off knowing your fuel has unknown behaviors it's part of the pre-flight. G100UL should be grounded 

[Pinecone]

16 hours ago, MikeOH said:

Well, let's take your points one at a time:

2) Please explain, as I asked in my rebuttal to George, how is he then managing to fill his truck from a tanker truck with all these rules, obstacles, and costs?  Yet, it's impossible to do the same for 100LL??

I guess you did not READ the posts about the fuel being introduced.

RHV has an old underground tank that was not being used.  They resurrected that for the G100UL

[MikeOH]

6 minutes ago, Pinecone said:

I guess you did not READ the posts about the fuel being introduced.

RHV has an old underground tank that was not being used.  They resurrected that for the G100UL

That sounds like good news for other airports as RHV can’t be the only one with old underground tanks that can be resurrected.

[Pinecone]

Just now, MikeOH said:

That sounds like good news for other airports as RHV can’t be the only one with old underground tanks that can be resurrected.

There are not a lot of them.  USTs were taken out of service a long time ago.  Many dug up, others filled with sand.  Many requirements were added.  That is why you above ground tanks at most airports.

[EricJ]

If any aviation vendor comes out with a product that appears to create safety risks, I would hope people would speak up about it.   It shouldn't matter who blessed it or how much time or money was spent on it.

I'd also hope people would speak up about a product that is advertised to be compatible with legacy products but can actually damage your airplane.

We should be looking out for each other, not people who promote such products.

[George Braly]

15 minutes ago, MikeOH said:

That sounds like good news for other airports as RHV can’t be the only one with old underground tanks that can be resurrected.

Mike,

Actually,  RHV is a rather special case.  That "old" underground tank was the same tank that was used for 100LL until December 31, 2022 when they stopped selling 100LL.    

There are very very few residual (unused) underground tanks that are available. 

The problem they (KRHV) had with the pump for the underground tank most likely resulted from the fact that the seals and O-rings had deteriorated (dried out) from lack of use during the 24 month down time.  But that is just an opinion expressed to me by an old fuel tank installer who used to make his living doing that kind of construction work. 

George 

 

[George Braly]

14 minutes ago, EricJ said:

If any aviation vendor comes out with a product that appears to create safety risks, I would hope people would speak up about it.   It shouldn't matter who blessed it or how much time or money was spent on it.

I'd also hope people would speak up about a product that is advertised to be compatible with legacy products but can actually damage your airplane.

We should be looking out for each other, not people who promote such products.

Eric,

I do not disagree with what you posted.  At the same time, there is a minimal level of  evaluation for adverse claims about new aviation products that should be involved to make sure that one is not just repeating technically unfounded and unverified claims or criticism.

George 

 

[MikeOH]

42 minutes ago, George Braly said:

Mike,

Actually,  RHV is a rather special case.  That "old" underground tank was the same tank that was used for 100LL until December 31, 2022 when they stopped selling 100LL.    

There are very very few residual (unused) underground tanks that are available. 

The problem they (KRHV) had with the pump for the underground tank most likely resulted from the fact that the seals and O-rings had deteriorated (dried out) from lack of use during the 24 month down time.  But that is just an opinion expressed to me by an old fuel tank installer who used to make his living doing that kind of construction work. 

George 

 

George,

Thanks for your response.

I do wonder, however, how rare these tanks really are.  It is my understanding that two other airports, Tupelo and Watsonville, are offering both 100LL and G100UL.  What are they using?  Clearly, they have a practical solution that doesn't appear to involve too great an expense.

Also, while I appreciate your perspective on the cause of the tank pump seals and O-ring failures, I hope you can also appreciate the perspective future users might have on the other possibility for those failures: the known swelling effects of G100UL.  Nitrile/buna-N can't be 'all okay' if you also recommend changing to Viton.  Seems there is some rational basis for concern.

Again, as I, @EricJ, and others have experience in new product development and release we are a cautious bunch.  Speaking for myself, I have never seen a product NOT have some issues once it reaches the field in quantity (end users).  These issues need to be resolved before G100UL, or any unleaded fuel, is our only avgas choice.

It may not seem like it, based on my posts, but I do appreciate and respect the amount of work, time, money, and BS politics that you have, no doubt, encountered in this development.

Mike

[EricJ]

53 minutes ago, George Braly said:

Eric,

I do not disagree with what you posted.  At the same time, there is a minimal level of  evaluation for adverse claims about new aviation products that should be involved to make sure that one is not just repeating technically unfounded and unverified claims or criticism.

George 

 

People can use any threshold they want for pushing back on safety related issues or issues concerning potential damage to their property.   How the vendor responds will likely affect the public acceptance level and confidence in the product.   Continued deflection and victim blaming is not helpful.

[tony]

Here is the STC.  Read limitation number one.  Where does one get that approve their model Mooney?

g100UL STC.pdf

[Pinecone]

1 hour ago, MikeOH said:

Also, while I appreciate your perspective on the cause of the tank pump seals and O-ring failures, I hope you can also appreciate the perspective future users might have on the other possibility for those failures: the known swelling effects of G100UL.  Nitrile/buna-N can't be 'all okay' if you also recommend changing to Viton.  Seems there is some rational basis for concern.

Again, as I, @EricJ, and others have experience in new product development and release we are a cautious bunch.  Speaking for myself, I have never seen a product NOT have some issues once it reaches the field in quantity (end users).  These issues need to be resolved before G100UL, or any unleaded fuel, is our only avgas choice.

It may not seem like it, based on my posts, but I do appreciate and respect the amount of work, time, money, and BS politics that you have, no doubt, encountered in this development.

Mike

WHAT O-ring issues or failures?????

The only thing with O-rings is a test of some O-rings, NOT installed, in full contact with G100UL.

Remember, GAMI tested a number of aircraft devices with various O-rings installed without issues.

And, AFAIK, NO reports of issues from users of G100UL

[Ryan ORL]

1 hour ago, tony said:

Here is the STC.  Read limitation number one.  Where does one get that approve their model Mooney?

g100UL STC.pdf 386.1 kB · 9 downloads

In the referenced FAA Approved Model List (AML), which you did not attach here.

[hubcap]

I am not going to engage in the discussion other than to say, I will continue to use 100LL exclusively as long as I can.
 

When/if that is no longer an option, I will decide an alternative course of action.

[Justin Schmidt]

2 hours ago, MikeOH said:

I do wonder, however, how rare these tanks really are

Pretty rare... The federal epa and each state has very strict laws and regulations on old tanks. Whether underground, above ground, gasoline, oil, etc. they must be decommissioned properly such as draining, filling with concrete or sand, digging up, soil samples. Ask me how I know.

On another note not one oz of evidence has been shown that would remotely concluded g100 did it. From behavior I would wager an act of desperation. These threads certainly has created a libel case

[EricJ]

1 hour ago, Pinecone said:

WHAT O-ring issues or failures?????

The only thing with O-rings is a test of some O-rings, NOT installed, in full contact with G100UL.

That is an appropriate test for determining swell in o-rings, and they appeared to exhibit swell at or above the usual maximum limits for static application, and well beyond limits for dynamic applications.  Depending on how the assessment of swell is made, the swelling may even be well beyond that allowed for static applications.  Those levels of excessive swelling due to exposure to a fuel would indicate that it may be expected to cause issues with nitrile o-rings and hoses in systems exposed to the fuel.   Since one downside of excessive swelling is accelerated degradation and wear of the material, failures may be latent so imho safety concerns are more than justified for both o-rings and hoses.

[George Braly]

2 hours ago, MikeOH said:

George,

Thanks for your response.

I do wonder, however, how rare these tanks really are.  It is my understanding that two other airports, Tupelo and Watsonville, are offering both 100LL and G100UL.  What are they using?  Clearly, they have a practical solution that doesn't appear to involve too great an expense.

Also, while I appreciate your perspective on the cause of the tank pump seals and O-ring failures, I hope you can also appreciate the perspective future users might have on the other possibility for those failures: the known swelling effects of G100UL.  Nitrile/buna-N can't be 'all okay' if you also recommend changing to Viton.  Seems there is some rational basis for concern.

Again, as I, @EricJ, and others have experience in new product development and release we are a cautious bunch.  Speaking for myself, I have never seen a product NOT have some issues once it reaches the field in quantity (end users).  These issues need to be resolved before G100UL, or any unleaded fuel, is our only avgas choice.

It may not seem like it, based on my posts, but I do appreciate and respect the amount of work, time, money, and BS politics that you have, no doubt, encountered in this development.

Mike

We have been in touch with literally hundreds of airports around the country.  It is, indeed, very rare that anybody has a spare tank that is not presently used for 100LL or, in a hand full of instances,  for  94UL.   The 94UL tanks can, of course, be repurposed for G100UL Avgas, but, again, that is a very small number compared to the number of 100LL fuel FBOs around the country. 

Keep in mind,  our model year 2007 TN SR22 Cirrus has all original O-rings, seals,  tank sealant, etc etc.  That airplane has been operating on G100UL Avgas for 14 years.   If you were to ask an FAA certification engineer if that is "good enough" - they would rather uniformly tell you that is a "vastly" over any certification requirement.   

The C-172 at Embry riddle had a 1400 hour TIS engine.   That airplane then operated for ~ 200 hours over 9 months with G100UL Avgas.  All original OEM seals, O-rings, etc.   No leaks.  No drips.  No paint stains.  No paint damage.    We specially asked the FAA to allow us to use a high time engine for that testing, rather than a newly overhauled engine to be used for durability testing - - for the specific reason that we anticipated a lot of  "... yeah butwhatabout" type questions from pilots with used / higher time engines.   The FAA worked in a collaborative way with GAMI to develop that test plan.  We ended up getting the "best of both" worlds.   We removed two of the four cylinders and measured all of the internal parts that we were able to access, and then measured up all of the parts for two new cylinders and installed those.  Then ran the airplane and engine through a full certification program over the next 180+ plus hours.  The engine passed the test with very generous wear margins, and the 1400 hour cylinders remained full serviceable and eligible to go on to TBO+. 

Unless one is just philosophically opposed to any change - -  that kind of real world experience would normally be received by most observers as rather convincing.   

George

[George Braly]

On 1/1/2025 at 1:59 PM, George Braly said:

 

I think it is rather inappropriate to state that I give "deflective" answers to your questions.   What I have provided is hard data.  Exposure data with controls.   

There is simply not enough information about the circumstances in California with the Mooney for us to be able to do any more than speculate.  

We are continuing to investigate the matter.   That does require some time.   If I recall, one of the U-Tube reports "dropped" one day before Christmas.   This is New Year's Day. 

What I do find somewhat frustrating is that, when GAMI does provide relevant aircraft paint exposure data - - with experimental controls - -  that data is dismissed  by several of the participants here, as not being sufficient to further the discussion. 

Regardless, as stated above,  we will, with all deliberate speed, continue to investigate the matter. 

 

 

For follow up on aircraft paint compatibility with G100UL Avgas - - - 

See the following links:

https://g100ul.com/faq#fuel-testing

https://www.youtube.com/watch?v=zrOoq-sB1Ig

[A64Pilot]

Ref underground tanks.

They are a nightmare, a ticking time bomb that once a leak is detected it’s going to cost huge amounts of money to rectify. We had one at Thrush that hadn’t been used in years, but had monitoring wells around it, checking for leaks of course for the empty tank, EPA required, why I don't know, that was before my time, it was a fiberglass tank.

I dug it up with my old backhoe and disposed of it.

I replaced it with an above ground tank, you have three options with those.

Mobile as in on wheels, that has essentially no restrictions and was my temporary measure. 

For a fixed above ground tank it can be either a double walled tank with provisions for checking to see if the inner tank is leaking, or if single walled it has to sit in a concrete containment that can hold the entire contents of the tank, of course this containment has to have a drain for rainwater, most often you find them with the drain open.

I went with the double walled tank, it was actually a little cheaper

[MikeOH]

4 hours ago, Pinecone said:

WHAT O-ring issues or failures?????

The only thing with O-rings is a test of some O-rings, NOT installed, in full contact with G100UL.

Remember, GAMI tested a number of aircraft devices with various O-rings installed without issues.

And, AFAIK, NO reports of issues from users of G100UL

@Pinecone The conversation was about the failure of seals and O-rings in the pump for the underground tank at RHV.  George's position was that it was due to them being 'dried out' due to 'lack of use'.  I then posited that it could have been due to G100UL and the swelling issue. The root cause of their failure is NOT actually known.

[MikeOH]

2 hours ago, George Braly said:

We have been in touch with literally hundreds of airports around the country.  It is, indeed, very rare that anybody has a spare tank that is not presently used for 100LL or, in a hand full of instances,  for  94UL.   The 94UL tanks can, of course, be repurposed for G100UL Avgas, but, again, that is a very small number compared to the number of 100LL fuel FBOs around the country. 

Keep in mind,  our model year 2007 TN SR22 Cirrus has all original O-rings, seals,  tank sealant, etc etc.  That airplane has been operating on G100UL Avgas for 14 years.   If you were to ask an FAA certification engineer if that is "good enough" - they would rather uniformly tell you that is a "vastly" over any certification requirement.   

The C-172 at Embry riddle had a 1400 hour TIS engine.   That airplane then operated for ~ 200 hours over 9 months with G100UL Avgas.  All original OEM seals, O-rings, etc.   No leaks.  No drips.  No paint stains.  No paint damage.    We specially asked the FAA to allow us to use a high time engine for that testing, rather than a newly overhauled engine to be used for durability testing - - for the specific reason that we anticipated a lot of  "... yeah butwhatabout" type questions from pilots with used / higher time engines.   The FAA worked in a collaborative way with GAMI to develop that test plan.  We ended up getting the "best of both" worlds.   We removed two of the four cylinders and measured all of the internal parts that we were able to access, and then measured up all of the parts for two new cylinders and installed those.  Then ran the airplane and engine through a full certification program over the next 180+ plus hours.  The engine passed the test with very generous wear margins, and the 1400 hour cylinders remained full serviceable and eligible to go on to TBO+. 

Unless one is just philosophically opposed to any change - -  that kind of real world experience would normally be received by most observers as rather convincing.   

George

Then how are Watsonville and Tupelo able to provide both fuels?  Are they, along with RHV, the 'very rare' three in the US, or are they handling both fuels via some other method that could be used elsewhere?

For the sample size of two, your SR22 and the ER C-172, were the seals Viton, nitrile, or unknown?

I am not philosophically opposed to change as change is the only way progress is made!

I am pragmatically opposed to change when the downsides/risks outweigh the benefits, most especially when the driving reason for the change is much more political than performance based.

[gabez]

16 minutes ago, MikeOH said:

Then how are Watsonville and Tupelo able to provide both fuels?  Are they, along with RHV, the 'very rare' three in the US, or are they handling both fuels via some other method that could be used elsewhere?

For the sample size of two, your SR22 and the ER C-172, were the seals Viton, nitrile, or unknown?

I am not philosophically opposed to change as change is the only way progress is made!

I am pragmatically opposed to change when the downsides/risks outweigh the benefits, most especially when the driving reason for the change is much more political than performance based.

Kwvi had 4 tanks, 2 100ll and 2 jet, one jet was converted 94ul and then converted again 100ul 

[George Braly]

59 minutes ago, MikeOH said:

@Pinecone The conversation was about the failure of seals and O-rings in the pump for the underground tank at RHV.  George's position was that it was due to them being 'dried out' due to 'lack of use'.  I then posited that it could have been due to G100UL and the swelling issue. The root cause of their failure is NOT actually known.

Mike, 

While your speculation on the cause "might" be correct.  Those experienced in working with installing and repairing those tanks would tell you that your hypothesis is extremely unlikely.   

For example, we have had a 10,000 gallon tank here at GAMI with almost identical pumps, filters, seals, meters,  etc etc.  for the last 3 years.  I do not think we have replaced any component other than the routine and pre-scheduled change out of the filters.  The manufacturer of the filters tested those filters (as removed) and wrote us a report and stated they continued to be serviceable and showed no indication of any adverse effect due to the use of G100UL avgas. 

Stated differently, the fact that the old underground tank was suddenly de-commissioned, and then two years later put back into service without any refurbishment is the most likely root cause.  Your postulate and any others I can think of are small fractions on a probability scale. 

 

[George Braly]

4 hours ago, EricJ said:

That is an appropriate test for determining swell in o-rings, and they appeared to exhibit swell at or above the usual maximum limits for static application, and well beyond limits for dynamic applications.  Depending on how the assessment of swell is made, the swelling may even be well beyond that allowed for static applications.  Those levels of excessive swelling due to exposure to a fuel would indicate that it may be expected to cause issues with nitrile o-rings and hoses in systems exposed to the fuel.   Since one downside of excessive swelling is accelerated degradation and wear of the material, failures may be latent so imho safety concerns are more than justified for both o-rings and hoses.

Eric,

You are referring to a screening test. 

Keep in mind, these same O-rings were used with similar aromatic aviation gasolines for many millions of successful operating hours in high powered piston aircraft engines in the past. 

And, we have 14 years of experience with both static and dynamic use of those same (not recommended for replacement) o-rings and seals - - with not even a hint of any failure.     As well as with the ground handling equipment for the last three years. 

What you have written is not consistent with the real world experience and testing.  All of which was supervised and approved by 30 and 40 year experienced turbine and reciprocating propulsion engineers (and specially retained chemist) inside the FAA. 

George

[MikeOH]

28 minutes ago, George Braly said:

Mike, 

While your speculation on the cause "might" be correct.  Those experienced in working with installing and repairing those tanks would tell you that your hypothesis is extremely unlikely.   

For example, we have had a 10,000 gallon tank here at GAMI with almost identical pumps, filters, seals, meters,  etc etc.  for the last 3 years.  I do not think we have replaced any component other than the routine and pre-scheduled change out of the filters.  The manufacturer of the filters tested those filters (as removed) and wrote us a report and stated they continued to be serviceable and showed no indication of any adverse effect due to the use of G100UL avgas. 

Stated differently, the fact that the old underground tank was suddenly de-commissioned, and then two years later put back into service without any refurbishment is the most likely root cause.  Your postulate and any others I can think of are small fractions on a probability scale. 

 

Nevertheless, it is unfortunate that we don't really know and are left with probabilistic speculation.  Do you know what material the seals and O-rings were made of? That data would be relevant, as well.