Let's Get Technical
Thoughts on the Topic of Fuel
August 1, 2020
If you are in the process of building or restoring your own aircraft you can now send in a question to be answered in a future issue of the Minnesota Flyer by Technical Advisor Mark Manning.
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As Technical Advisor, Mark Manning brings with him over 38 years of aviation experience. He has performed maintenance on over 35 different types of aircraft and has flown more than 25 different models of aircraft.
I get a lot of questions on fuel so here is what I have experienced.
One question that comes up is, I have an STC for auto gas so can I use whatever type of auto gas is available with the octane rating required in the STC? Yes, you can but I suggest using only premium non-oxygenated (it has no alcohol added) gas. Another question is, can I just use auto gas- it has the same octane rating as placarded on my airplane? No, you need the STC. Auto gas is not listed in the Type Certificate Data for the specific manufacturer.
The reason I suggest only premium non-oxygenated gas is because I was on a training session a few years back at a gas supply tanker farm which supplies fuel for various gas stations. You may not have thought about it much, but most of the auto fuel, no matter which gas station you go to, all comes from the same tank farm with each supplier adding their own additives to meet their specs. The only common gas between the different gas stations is the premium, it comes from the refinery with no additives or alcohol. Most of the other gas is made up by blending regular and premium with additives including alcohol.
I also suggest using some 100LL avgas for the older engines. The auto fuel has no lead so using a little avgas will provide that. I use about one gallon of avgas to five gallons of auto gas in my airplanes and it seems to really limit that odd smell of auto gas also, (just my personal thing about the smell of auto gas in an airplane). Something else to consider is if you are not flying on a weekly or monthly basis auto gas doesn’t store well for long periods of time.
Hope you are all having some fun this summer flying and remember to keep the fan turning it keeps you cool.
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