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.

Please identify each sponsor of an Unleaded High Octane candidate replacement for 100LL who has not publicly stated or acknowledged that their candidate UL fuel will require modifications of the engines in order to pass detonation test requirements.

Please share with me any information you may have on that subject of Shell in Europe doing testing on a new fuel formulation. There is no hint of that within the EAGLE / PAFI group to the best of my knowledge . Further, just before Christmas, I was in Europe and I meet with several of the senior leaders in the European general aviation world and they had no knowledge of any activity for a high octane unleaded fuel being developed anywhere within the European Union or in the United Kingdom.

As I understand the situation - - Shell currently does not produce one drop of 100LL anywhere in the United States. I think it still produces some 100LL - - maybe in Holland. Again - - there are a lot of "facts" associated with this 30 year process. It takes a "deep dive" into both the current and past refining structure / infrastructure and a similar deep dive into the (so far) unproductive "industry" (ASTM / FAA / Taxpayer / PAFI / EAGLE) history to fully appreciate how we got to where we are today.

The Swift 100R has about 25% ETBE. But the ethanol fraction of the ETBE is supposed to be controlled by an ASTM production spec for ETBE so that it is not more than 1% of the ETBE. So the amount of ethanol in Swift 100R should be relatively small. [However, we have seen some very peculiar material compatibility issues with 25% ETBE fuel chemistries.] The basic Swift Patents suggest a fuel chemistry that would be ~ 25% ETBE & 70% "high grade aviation alkylate" and ~ 3-5% butanes or iso-butanes for vapor pressure. Swift claims the "supercharge" rating is > than 130. But that is only obtained at a F/A ratio that is "off scale" higher than any actual F/A ratio that is used by our engines. The ASTM D909 laboratory supercharge test data for one similar fuel chemistry reflects a supercharge rating of only around 115 (rather than ~ 130 for 100LL and > 150 for G100UL avgas) at the full power / full rich Fuel-Air ratios typical of our fleet of high powered engines. ETBE is potentially useful for aviation gasoline, but only if one is able to "manage" or "mitigate" ETBE's own set of problems. The detonation characteristics are such that it is - - (in our judgment, and based on our test data of ETBE fuel blends we have made IAW the reported Swift 100R fuel chemistry and then tested in back to back testing with 100LL and G100UL avgas on our test stand) - - rather unlikely that Swift 100R could be used for any of the high powered engines without significant "adjustments" to the engines, such as retarding the timing or reducing the redline CHTS and imposing limits on the IAT, or likely, some combination of all of the above. But we may be "missing something" in our evaluation and analysis. Always open to new information.

Kelpro, Sometime in the 2011 time frame, Continental asked us to send them four drums of G100UL avgas for Continental to test in Mobile. ~ 3 years later, I called them and asked them for a copy of their test report. "We have not had time to test your fuel." After a rather surprised moment - - I then asked them where the fuel was stored. "In an open shed here in Mobile." Then I had them ship it back to us to use for long term storage stability testing. I think I still have one drum of that that has never been opened! The fuel was still "conforming" to the specification when it was returned. It had last a small amount of vapor pressure, but that is normal for any fuel. George

Sabre, You may be right on the regulatory issue. I have not researched that. But what you stated explicitly contradicts the Bendix document. And - - regardless of whether or not your regulatory interpretation is correct: Failing to comply with that 1980 Service Bulletin - - absent a LOT of explicit log book documentation and warnings to the owner(s) of the aircraft - - the failure to comply with a SB relating to the fuel system - - would likely subject the mechanic to some serious liability in the event the fuel servo failed and resulted in an accident. George

Please educate me: Private responses are fine: gwbraly@gami.com For those of you that are concerned about fuel leakage and possible paint damage, please let me know the following: 1) Year / Make Model; (Optional N number) 2) Year when last painted. 3) Type of paint when last painted, if known. 4) Is your wing currently "weeping" or otherwise exhibiting any indication fuel leakage ? (Photographs would be helpful.)

Not only are nitrile / buna N parts generally "life limited" - - if they are in a Bendix fuel unit - - there is supposed to be an expiration date sticker on the unit that alerts the mechanic that the unit must be overhauled before the aircraft can be returned to service. If, and only if, the unit is fully serviced and ALL of the nitrile seals are replaced with fluorosilicone - - can the life limit sticker be removed from the unit.

As I interpret your certification / approval standards: Boeing, Airbus, Cessna, Piper, Cirrus etc would have to take a newly designed aircraft and put it into service with empty cabins and fly multiple versions around for thousands of hours and years - - before they could ever allow the airlines or the private pilots to accept delivery and begin service with passengers on board.

When is "good enough" - - good enough? 1) 14 years of use in a Cirrus fiberglass wing / fuel tank , with standard Continental fuel system (electric boost pump/ hoses / fittings/ fuel selector / engine driven fuel pump / fuel filter / fuel gascolater / - - - AND ALL OF THE STANDARD O-RINGS, GASKETS, DIAGHPRAMS , SEALS, etc etc etc associated with the OEM system. RESULT: No drips. No leaks. No paint stain. No sealant issues. If that is not "good enough" - - then how much is ? 2) Nearly one year and 200 hours of fully independent testing done by Embry Riddle. C 172. with standard LYCOMING fuel system ( hoses / fittings/ fuel selector / engine driven fuel pump / fuel filter / etc etc / - - - AND ALL OF THE STANDARD O-RINGS, GASKETS, DIAGHPRAMS , SEALS, etc associated with the OEM system. All of those components disassembled and inspected by ERAU and by the FAA - - independent of any involvement by GAMI. RESULT: No drips. No leaks. No paint stain. No sealant issues. ALL components were deemed to be fully airworthy. 3) 12 months and ~ 200 hours in a Baron with one 46 year old fuel bladder and one 50 year old fuel bladder. One with G100UL and the other with 100LL. BOTH leaked. The 100LL bladder leaked after about two weeks of exposure. The G100UL bladder after about eight months. Both had multiple internal pre-existing repairs and multiple pin-hole air-leaks. Otherwise, no issues with the operation of the two Baron engines. In addition: Repetitive OIL samples document that engine wear metals decreased by ~ 50% on G100UL vs 100LL; Repetitive bore scope inspections reveal no valve seat issues; Repetitive spark plug inspections reveal the G100UL side spark plug electrodes remained free of any deposits and the 100LL side had "generous" deposits on the electrodes and required servicing. 4) A 1944 Douglas A-26 "Invader" has had G100UL in those fuel tanks for over seven months. No drips. No leaks. No paint stains. ********* When is "good enough" - - good enough? ********* Observation: One Mooney fuel tank repair shop manager recently told me that, based on his experience, 80-90% of the Mooney fuel tanks he works on have had improper repairs to those tanks. Often with the wrong repair sealant. George