Swift Fuels’ 100R unleaded fuel appears to have no adverse effect on paint, seals, and fuel lubricants, according to California pilot and engineer Michael Luvara after a series of hangar bench tests. In his seventh video on the compatibility of fuels with various materials and components, he says 100R was comparable to 100LL and 94UL in terms of impacts on aircraft systems. G100UL damaged paint and aircraft fabric in his tests to the point that Luvara suggested there might be airworthiness concerns about its effect on two types of aircraft fabric. GAMI founder George Braly told AvBrief he conducted a drip test of G100UL on the fabric-covered aileron of an A-26 and its effect was similar to that of 100LL.
Luvara also notes that 100R’s detonation performance, particularly in big-bore, boosted, and high-compression engines, including those used in warbirds, has not been publicly disclosed and there is much discussion that those engines will have to be detuned to be able to use the fuel. That could severely limit the usefulness of those engines, which burn about 70 percent of the avgas sold. For now, 100R is restricted by STC to use on late-model Cessna 172s, which don’t require 100 octane fuel. A California flight school has burned 35,000 gallons of 100R in its R- and S-Model 172s with no adverse effects noted and a reduction in the metal levels in engine oil. Calcium levels increased and Luvara speculates that is the result of an additive used to prevent valve seat recession.
In the video, Luvara submits 100R to the same sorts of tests he conducted in previous videos, which also became a timeline of the progressive impacts of G100UL on some aircraft. He says an insurance company wrote off a Cessna 421 to the tune of $600,000 for damage attributed to G100UL. Luvara says he will tackle the potential performance issues in a future video.
600K is very optimistic valuation for a C421
So, 100 R isn’t really a replacement for 100 LL? Is the R for reduced horsepower?
It’s deeply suspicious that the only aircraft flying with 100R are ones that don’t actually need 100 octane fuel and were already operating on 94UL before the “test”.
I’d sure like to hear more about this alleged write-off of a 421. Even if G100UL ate all the paint off the plane, ate all the seals, and ate the fuel tank linings (none of which seem likely), it’s hard to imagine how you get to totaling a $600k airplane.
This is what years of research has wrought? Those of us with big bore engines still need 100LL. Move along folks, nothing to see here.
As long-time user of UL94 from Swift in our Comanche, I’d suggest waiting for rollout process of 100R to play out before making judgments or even assumptions. The FAA has to act to broaden authorized aircraft listing, the Warbird and big-engine crowd need to gain experience with 100R and it will take years to replace 100LL nationwide even if it is a perfect drop-in replacement. I take as a positive fact that experience in San Carlos and Mike Luvara’s testing haven’t revealed the kind of issues that are showing up with GAMI’s fuel.
First, hats off to Mike for his “ASTM” testing. What a fantastic individual effort to help us all!
Second, getting the lead out has clearly been a struggle, but inevitably must occur as the environmental and supply pressures mount.
I’m old enough to remember 145 octane avgas. There was handwringing then when it went away, and yes, some compromises seem to be in the cards for the big-bore and high compression engines. Since we’re flying with the finest in 1940s and 50’s technology, you’ve got to hope that some enterprising minds will find a way. Either that or these museum pieces will become just that.
At some point *ONE* fuel is going to have to rule them all. I can’t imagine FBOs stocking Swift, GAMI, and whatever other players there may be in this game. It seems to me that the stakes are *very* high.
Russ, I spoke with George Brayley about his “paint test” and determined that the part that he used to soak in his 100UL was an old part off a very old Bonanza. I projected that such an old part would have been painted with the “old” pre-reformulated Imron, which was tough as nails, and that the staining and peeling complaints would have been with water based reformulated paints (Jet-Glo perhaps?).
So, along comes Swift — but what paint is on the aircraft that they are testing? Why haven’t the paint manufacturers voiced into this?