Jeff Scott wrote:

> After years of running Mogas in both the O-200 in my KR, and the O-320
> in my SuperCub, I have run into a particularly nasty bunch of Mogas
> after moving to Arkansas.

Welcome to the boondocks Jeff! I used to buy my ethanol-free mogas (for the Swift and the KR2S) at an el cheapo independent station named something like "Fuel City". A few years ago I dropped by and filled up six 6-gallon cans, and I noticed a very funky smell while filling them. Later, as I was filling the Swift which has a STC for mogas, (thanks EAA!), I noticed the same funky smell, and realized it was the fuel, not just the side of town where I got the fuel. This was cause for a serious crossing of the fingers, and hoping for the best, although the smart thing to do would have been to stop pouring it in the Swift, and take it back where I bought it for a refund!

Since I was just fueling it up for the next flight, I left it until the following weekend when I was ready to take it for a spin. When I opened the hangar door, the same funky smell was overpowering, and I noticed the two fuel hoses that connected the main tanks (aluminum, thankfully) to the center pickup "header" were dripping the foul stuff, and the tanks were completely empty!

I don't know what was in that fuel either, but I know it wasn't "pure" ethanol-free auto fuel! I remembered back to a local EAA chapter presentation by Ken McCutcheon, founder of the "Aircraft Engine Historical Society" here in Huntsville, who talked about auto fuel rather disparagingly, and brought up the concept of "plug gas", which describes how fuel and other chemicals are moved in pipelines, with a "plug" separating the auto fuel from "God knows what" chemical is behind or in front of it in the pipeline, and it's bound to get mixed together in the process.

Since then, I've felt a lot better about pouring pure 100LL in the Swift. I still run mogas in the KRs, but I get it from the same Raceway that I've bought almost all of the fuel that I've run through my GTI and my wife's A4, which has ethanol, but at least no other rubber-eating chemicals in it!

See enclosed photo of what it did to my fuel hoses. Fortunately it was never run with this fuel in it, so the rest of the fuel system is fine, and has been inspected to prove it. See enclosed photo of what some chemicals can to do high quality aircraft hose, not to mention carbs, pumps, etc.

I will say that I have no hesitation buying the 89 octane ethanol free fuel that Raceway sells nearby, and that's what I run in the KR2 now, and will likely run in the Swift when it's running again in a few months. After 30 years of buying Raceway fuel, and after seeing a guy clean out the tanks and change the filters at the local station quite often, I'm convinced that they take fuel delivery contamination very seriously.

Check out the enclosed photo....

Mark Langford

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