G100UL - fuel leak

[Marc_B]

On 12/15/2024 at 12:04 PM, George Braly said:

With respect the discussion about the high levels of toluene and aromatics sometimes found in 100LL,  see the attachment, which is a "DHA"  (Detailed Hydrocarbon Analysis)  using a standard ASTM test method, that was run at the reference fuel laboratory (Dixie Services, Deer Park, Tx) from a sample pulled from our local FBO 100LL, supplied by rail from the Phillips refinery in Borger Texas.

This sample from 2010 seems like an outlier.  Do you have a current sample of 100LL compared with a current sample of G100UL?  Thanks for helping to understand this!

[Fly Boomer]

1 minute ago, Marc_B said:

This sample from 2010 seems like an outlier.

Have you seen other samples that would demonstrate that it's a outlier?

[Marc_B]

1 hour ago, Fly Boomer said:

Have you seen other samples that would demonstrate that it's a outlier?

Outlier compared to (google search for "100LL SDS") of the SDS for 100LL from a variety of manufacturers...

EDIT FOR CLARITY: I didn't find one that had 29% toluene.  Most showed <10-15%.

This was the SDS source I showed the picture from (Phillips 66 SDS):

https://www.aviation-fuel.com/pdfs/MSDS_for_AvGas_100LL_from_P66_dated_3-04-13.pdf

 

 

[Fly Boomer]

Just now, Marc_B said:

Outlier compared to ANY of the SDS for 100LL from a variety of manufacturers...

 

I'd like to see those if you know where to find them.

[George Braly]

>>As an aside, is it even established that it's Toluene that's causing damage to sealant/paint?<<

For the 100LLs produced up until the last few years,  it was common for them to have as much as 29% toluene and then another 3 or 4% other aromatics for a total around 33% aromatic content.  The vast majority of that was simple paint store toluene. 

The last 100LL sample I had analyzed by DHA at the lab was a decade ago.  I have posted that analysis.  Can do that again.

But, yes, it is the toluene that did that for 100LL.   

Some of the 100LL only had about 15% toluene, but from the refineries with lower quality aviation alkylate - - they used increasing toluene to provide the octane they needed. 

Xylenes are a related molecule, but less aggressive chemically - - according to the retired refinery - expert chemist retained by the FAA in 2012 to do an independent evaluation of the G100UL avgas fuel chemistry. 

George

[Fly Boomer]

2 minutes ago, Fly Boomer said:

I'd like to see those if you know where to find them.

I found one that shows identical concentration:

https://www.aviation-fuel.com/pdfs/MSDS_for_AvGas_100LL_from_P66_dated_3-04-13.pdf

[George Braly]

Here is a modest proposal:

If the Mooney folks would like to learn more,  GAMI will offer to host a "Mooney Delegation" here at Ada.  

Maybe anywhere from 3 to six participants ? 

I will print out all of the material compatibility test data that the FAA has approved and we can sit down around a conference room and review that.   I will answer any questions.   

In the process you can get a chance to see the engine test cell and maybe have an opportunity to observe while it is run on G100UL vs 100LL vs "other"  PAFI/EAGLE type fuel chemistries. 

There may be some additional items of interest. 

Let me know? 

[Fly Boomer]

10 minutes ago, Marc_B said:

Outlier compared to ANY of the SDS for 100LL from a variety of manufacturers...

 

Here is another more recent SDS that shows substantially higher concentrations:

https://www.epc.shell.com/DocumentManagement/BlobDocumentDownload?DocId=119466305

 

[Fly Boomer]

16 minutes ago, Marc_B said:

Outlier compared to ANY of the SDS for 100LL from a variety of manufacturers...

 

Here is a third one from ExxonMobile that shows a wide range, but the upper end of the range appears to be higher:

https://www.msdsdigital.com/system/files/Avgas 100LL.pdf

[Fly Boomer]

20 minutes ago, Marc_B said:

Outlier compared to ANY of the SDS for 100LL from a variety of manufacturers...

 

Here is a fourth from Chevron that shows a wide range, but the upper limit is higher.  I don't see the one George showed as misrepresenting the toluene in 100LL from a variety of manufacturers:

https://cglapps.chevron.com/sdspds/SDSDetailPage.aspx?docDataId=431702&docFormat=PDF

[Marc_B]

1 hour ago, George Braly said:

If the Mooney folks would like to learn more,  GAMI will offer to host a "Mooney Delegation" here at Ada. 

Mr. Braly, I'm sure that many of us (and probably more than 6) would love to learn more and see the shop in Ada!  I always had the Advanced Pilot Seminar on my bucket list and I think it used to be held in Ada?

56 minutes ago, Fly Boomer said:

Here is a fourth from Chevron that shows a wide range, but the upper limit is higher.  I don't see the one George showed as misrepresenting the toluene in 100LL from a variety of manufacturers:

My comments shouldn't be seen as inflammatory and certainly didn't have that intent.  The SDS sheets I saw mentioned <10% toluene; @Fly Boomer you found one with <15% and <20% and the sample Braly shows from 2010 has 29%.  That's still is a decent difference.  I'm aware that there are variations from manufacturers and even from batches.  G100UL SDS shows up to 40% xylene and up to 5% toluene.  But how accurate are SDS and do they reflect product at the pump??

A single fuel sample from 2010 doesn't really help understand a comparison for composition of G100UL and 100LL; especially if current fuels aren't reflective of that sample.  And certainly doesn't help to understand what happened to the tank in this thread and if it has anything to do with G100UL.

[Marc_B]

41 minutes ago, Fly Boomer said:

I don't see the one George showed as misrepresenting the toluene in 100LL from a variety of manufacturers:

That wasn't what I'm implying.  Rather, does this sample from 2010 reflect the 100LL we're currently using and does it reflect the averages that the 100LL fleet used?  I'm not a chemist.  Just trying to learn more about the products we use.

From ASTM D910:

X1.8.1 Aromatics Content—Low boiling aromatics, which are common constituents of aviation gasolines, are known to affect elastomers to a greater extent than other components in aviation gasoline. Although Specification D910 does not include an explicit maximum aromatic limit, other specification limits effectively restrict the aromatic content of aviation gasolines. Benzene is virtually excluded by the maximum freezing point of −58°C, while other aromatics are limited by the minimum heating value and the maximum distillation end point. Thus, the heating value limits toluene to about 24 %.
Xylenes have a slightly higher heating value and, therefore, would permit somewhat higher aromatic concentrations; however, their boiling points (above 138°C) limit their inclusion at levels not higher than 10 %. Total aromatic levels above 25 % in aviation gasoline are, therefore, extremely unlikely.