George Braly

Mike, I am aware where those photos came from. I have been double checking and trying to verify from some contacts in PAFI / EAGLE that those pictures are from 100LL. As a side matter - - PAFI / EAGLE has been less than "transparent" about a lot of their data. Also, there are not and have not been any fuels in the PAFI program with significant aromatics that have been tested by PAFI / EAGLE. However, based on my understanding of the various aircraft that were tested and that used those various test fuels I have reason to believe this airplane make/model was not one of the PAFI test planes. I think the PAFI / EAGLE folks may have used this as a convenient example. In any event, there are other similar pictures available that demonstrate similar appearances that were documented from years ago before PAFI/EAGLE ever came into existence. When I run across those, I will try to post those up, also.

Marc, I wish I had the band-width to jump into this with more time and data. However, claims that 100LL does not damage paint - - are contrary to lots of observations from the field. Let me try to verify the source of the fuel in that photograph - - in the mean time, I deleted it from the post. I apologize for any confusion. Let me try to get better data. In the mean time, I have to (get to) go fly a new experimental turbo system! George

Schllc, Give me a call tonight or tomorrow sometime. I would like to discuss this with you. 580 421 5645 is my cell number. Do you have borescope pictures of the inside of your Mooney fuel tanks ? George PS. As an interesting coincidence: - - My name is on some of the original 1967 engineering drawings when (in the engineering room at Northridge, Ca.) we redesigned the Aerostar wing tanks (which had, for the Aerostar "360 & 400", previously been "dry wings" - - to become "wet wings." That was for the prototype and then the production series of Aerostar 600,601, & 601P models.

With respect to your observation: "If it does NOT leak with 100LL . . . " Mike, Integral (non-bladder non-welded) aluminum - riveted fuel tanks have been leaking (on 100LL ) within relatively short periods of time (2 to 10 years after original construction) since at least the 1970s. There are three long term repair shops that specialize in cleaning and re-sealing Mooney integral fuel tanks (and others of similar construction.) Examples: 1) Mooney fuel leak 100LL https://youtube.com/shorts/rMqENgH2udo?si=5_aVNdzOYtqxfmmI 2) Identifying a leak on a Vans RV-10 fuel tank - 100LL https://youtube.com/shorts/-zXeFLsfUhU?si=F09FtUxW26eAUmIS 3) Cirrus SR20 fuel leak from 100LL https://youtube.com/shorts/3j53EHFpVzo?si=0RZa31jYdr8QhUg6 4) Resealing a leaking Piper fuel tank. https://youtube.com/shorts/K4FwEgt86iQ?si=21tI-6xqaaDxKHD8

I agree - - That looks like they did a nice job. I think all three of the companies that do (re-do) Mooney fuel tanks do a much better job than was originally done at the factory. But there are several devils in the details that are not detectable from visual inspection. Examples: A) Proper cleaning of the old sealant is extremely important; B ) and then there is fairly detailed requirements for "surface preparation". C) Then there is normally a "recommended" "adhesion promoter" - - which very few shops use. It is not mandatory. But it sure does help in improving adhesion to the substrate. D) Each sealant variety has a different "pot" or "useful working life" after the two parts are first mixed together. If it is 30 minutes, and you are still putting sealant down at 35 minutes, then the cross-linking of the molecules in the sealant with the substrate will be greatly degraded. Those are among the several things we have learned as we investigated material compatibility issues with sealants over the last several years.

Nicely done. Very. Do you know when your tanks were last sealed ? If ever ? Or how old the sealant was before you had the tanks resealed ? George BTW - - one is at a loss for words to describe the difference in the quality of the workmanship - - "before" and "after". Unfortunately - - the condition of your tanks before being resealed is something we have seen before.

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!

You are misinformed. There is standard liability coverage for the fuel being sold to the FBOs in California and elsewhere. Identical or essentially identical to that presently in place for most of the FBOs selling 100LL.

I have been ramp checked (randomly) at least six or 8 times over the years. More recently - - when we were at the AOPA airshow in Buckeye Arizona last year - - two FAA inspectors showed up on the ramp in a golf cart while we were installing the STC and placards on the Baron owned by California Aeronautical University which they brought down to do formation fly overs at the Buckeye air show in two Barons operating on G100UL Avgas. Initially, the two FAA inspector's "attitude" was in full blown "enforcement" mode. They were a bit in disbelief that we were actually going to put unleaded avgas in the CAU baron. So they demanded to see all of the paperwork. STC. Installation Instructions; ICAs; Apprvd FMS; etc. While they were standing there we were putting the placards on the wings next to the fuel filler ports. About that time, a local I.A. drove up in a golf cart and jumped out and said, "where do I sign ?" He signed off the log book and the 337 and left. The two FAA inspectors walked around the airplane and came back to me and thanked me for our cooperation and expressed their satisfaction that all of the paperwork details were in good order.

I think, sometime in the 1990s, the Congress made it a federal criminal offense to use an STC without the required permission of the owner of the STC. But I have not gone back and verified that in 15 years or so. My memory may be fooling me. That happened because of complaints that people were just doing xerox copies of their neighbor's STCs.

The missing pieces of paint (very old paint) were already present when the airplane came to GAMI in Ada in October of 2023. The tan / brown staining on the fuel cap is from fuel spills after the airplane left GAMI sometime in the spring of 2024. It had been refueled by us multiple times with no brown stains. The "good fuel hygiene" protocol is to simply absorb / wipe up the fuel in a timely manner, if it is spilled. How to prevent ? A good application of crystal coating or a graphene coating in that area is very helpful. Good fuel hygiene is still called for. But with the crystal or graphene coatings, one can often "buff out" any stain - - but it takes some elbow grease. In fact, after our extensive testing of those coatings during the summer and fall of 2024, I am seriously impressed by their effectiveness. Simple to apply. Makes maintaining the paint (anywhere) on the aircraft much easier, and makes bug removal on the leading edges much easier.

In the case of the four airplanes we have run tests on, the OEM elastomeric components were traditional nitrile.

I thought I had made that clear. If not, my apologies. They were the OEM designated O-rings and seals. They were not replaced or "upgraded" before any of the testing.

Actually - - a Lycoming IO-360 is one of those engines.

Respectfully, I think the request to identify any candidate fuel that even, now, remotely, claims to be suitable for use for the fleet - - without significant individual modifications to the engines - - is rather important to your questions. Someone can be "... working on a fuel" - - but if that fuel is not going to meet the goal as being useful for the entire fleet of airplanes and engines - - then the significance of each of those efforts is rather seriously diminished. " Do you think another company is not capable of producing a product to compete with GAMI? " What I think is likely irrelevant. What I know is that the P66, Shell, and others have claimed to be working towards that goal for the last 30 years. Both P66 and Shell failed - - miserably - - during their participation in the PAFI program and formally withdrew any further participation in that program.