General Aviation Modifications Inc. has completed its own version of a 10-day simulation of a slow leak of its G100UL unleaded fuel and no paint damage resulted. In the video results below, GAMI founder and chief of engineering George Braly says the fuel was allowed to drip and evaporate on a side panel from a Bonanza with 20-year-old paint. The paint was stained by the dye in the fuel but GAMI was able to clean that up with normal shop techniques.
I had a slow persistent drip of 100LL onto a landing gear door that created a big blue stain that I have yet been able to remove. Also, I see fuel stains under the majority of wings I peek under at airports. Is GAMI fuel worse or are we just now noticing how fuel can stain paint?
This is ongoing seepage which evaporates before hitting the ground, as opposed to an ongoing drip. The evaporated seepage can leave behind hydrocarbons in higher concentrations than you’d find with a steady drip.
I love the age of TikTok and Youtube. It wouldn’t occur to GAMI to maybe talk to the A&P, maybe fly out to see his results, or have his evidence shipped to GAMI to inspect. Instead, we need a public video with a half-assed experiment in “reply”.
Imagine if, after an airline crash, the government just published a YouTube video (with unknown methods or evidence) blaming it on the airline, and the airline published their own video blaming it on the government. Lots of drama, but no science, no progress. Just people talking past each other.
Maybe the freshly whipped-up batch of G100UL in GAMI’s labs acts differently than the stuff that came on the mystery truck that drove to California and dumped it into the mystery tanks that were then pumped into a mystery aircraft and then drained into a mystery container at an A&P? I don’t know, maybe these mysteries are more important than the video?
Steve Miller’s observations are clearly the direction this discussion should be headed. The GAMI test should have been done with the same fuel that the accuser was using. Although, an environmental chemist, not a material annalist, that would have been my first objective.
If I were GAMI, I would have flown over there the following day, that this report came out, and secured several jugs of the fuel that was being accused of mischief, probably with a chemist and a lawyer in hand to document the sampling.
So should we trust some random A&P’s evidence instead of the chemists who made the fuel? Are we certain that his fuel wasn’t contaminated? Did he try to clean the paint afterward like GAMI did? Ask I saw was that he said the fuel stained the paint. Which GAMI had already warned us about.
Maybe we should have some neutral trusted third party test the fuel. Like perhaps the FAA. Which they did before they approved the STC.
I agree completely with you. Was it the truck? The pump? The aircraft? The container used by the A&P?
Perhaps it’s not the fuel at all, but if it were any of the other things, that is still a problem that needs resolution for the use of G100UL. Maybe it mixed badly in the truck? Maybe the airplane flew in extreme cold or heat which caused a chemical reaction? Or maybe the airplane’s tanks were sealed with something unusual? Maybe the A&P used a polyethylene container? I don’t know, but an investigation seems far more useful than a “reply” video.
I agree with several of the comments that GAMI should be grabbing samples of the same fuel that Michael Luvara used to understand why their test didn’t yield the same results. Michael’s tests were quite transparent in his video and not overly complicated (two pieces of the same painted material, one in 100LL, the other in 100UL, then time-lapse for 3-5 days; 100% paint deterioration on ~17 different samples).
One Hypothesis for GAMI to test is that their video had the slow drip on the core painted surface without any meaningful “edge” exposure whereas Michael’s video had pieces where the “edge” was exposed to the GAMI fuel for several days. It appears that this is where the paint bubbling starts as perhaps the 100UL starts to attack the primer or paint and then it spreads, lifting and dissolving the paint as it goes. The pictures of the Mooney, C421, AOPA Baron, and RV7 all show the paint lifting at these “seams” where there’s an opportunity for the fuel to “get under” the paint.
If this hypothesis is right, do we “care”. My sense is “yes, we care” since every aircraft will have these seams and it’s highly likely that not all fuel can just be “wiped off” (leaks, vents, fuel drains, …) and therefore it would be likely that all planes would start to experience paint separation at these seams over time.
It would be great for GAMI, and for other’s out there who are independent like I believe Michael Luvara is, to conduct additional tests to determine if my hypothesis is right and, if so, is there anything that can be done to mitigate the issue of fuel attacking the paint at the seams/edges? Or, if we discover that the fuel, or containers, that Michael Luvara used was somehow contaminated and not representative of 100UL in the field, then that would be a great learning as well. This sounds like this test could be done quite easily, and quickly, to remove the conjecture that’s swirling around now.
Ah ha! Twenty year old paint. Before fish friendly primer substitute!
But seriously, I was involved in a significant amount of alternative fuel testing under PAFI from 2014-2016. Many of the candidate fuels experienced significant changes during storage and most had more agressive and volatile components. Most had some level of undesireable interactions with fuel system components. In context of those tests, it is no surprise at all that GAMIs offering has similary “issues.”
The key here is not to deny or hide, but to address. To move forward with these new fuels, the players have to admit defeat when needed and present a solution. Otherwise we’re all going to be grounded.