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Thread: New wing tanks

  1. #11
    Senior Member HighWing's Avatar
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    Default Re: New wing tanks

    I've been reading this and have a few thoughts. My first Model IV started flying in 1998 and I used mogas except on cross countries for nine years. California mandated all mogas have 10% ethanol in 2004. The original tanks were kreemed, and I re-Kreemed one tank bacause of some discoloration on the fabric below the tank. I then flew until late 2007 - three years with ethanol containing mogas primarily. My new Model IV has the Denney Aerocraft tanks with Kreem. I am using 100LL primarily because my flying is spotty and I have had serious issues with the mogas in infrequently used garden equipment and didn't want the same type issues in my Kitfox. I do use Decalin with the 100 LL. Then an article in the last issue of Sport Aviatrion - page 120 - talks about the pros and cons of mogas vs. avgas and in the article it mentions that the new Shell - Sport plus 4 has additives that keeps the tetra ethyl lead in suspension. It makes me wonder if the additive Shell uses would preclude the need for the Decalin. In other words, since Shell is adding an additive to the recommended oil that essentially does the same thing as the Decalin additive - is Decalin use still necessary.
    Lowell Fitt
    Goodyear, AZ


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  2. #12
    Senior Member jiott's Avatar
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    Default Re: New wing tanks

    Good question Lowell, my understanding of Decalin is that it actually alters the chemical composition of TEL when it is burned so that the residue (not 100% but a lot) is able to be blown out the exhaust rather than forming lead deposits on valves and piston rings. There are more in-depth discussions of this in the forum. Again, my opinion only, but the additive in Aeroshell Sport Plus 4 keeps the TEL in suspension in the oil that has been contaminated with UNburned fuel. All engines have a certain amount of unburned fuel that sneaks past the piston rings and into the crankcase oil. Therefore I would think that if you burn 100LL you would want to use both Decalin AND an oil with that additive. The Rotax gearboxes are very susceptible to lead deposits from the contaminated oil.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  3. #13
    Senior Member jiott's Avatar
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    Default Re: New wing tanks

    Regarding tank coatings, the older Kreem types or even newer stuff, I have seen way too many reports in these forums over the last 6 years I have participated of folks having serious problems with it flaking off and seriously plugging screens and filters. Mind you there are also many that swear by the stuff. To me it is too high of a risk of catastrophic engine starvation. If my uncoated new style ethanol "resistant" tanks SLOWLY over the years start to soften and even spring a slow leak, I think that would not be catastrophic and most likely would give plenty of prior warning-a much better risk situation in my mind. I would stay totally away from any kind of coatings in the newer tanks.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  4. #14

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    Default Re: New wing tanks

    I have a 2000 model skystar series 5. here in Australia they do not sell ethanol gas without stating. my tanks have been dry for 6-7 years due to being ground looped then i purchased it. they look very good and i am confident they with be fine and most likely would of had only 100LL over their 750hrs in use. should i be concerned as i am currently re bagging the wings but changing the tanks is one hell of a job for nothing.
    James Doyle
    Aussie aircraft engineer
    Series 5 barn find in repair
    912ULS-Kiev 3 blade-round cowl

  5. #15
    Senior Member Maverick's Avatar
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    Default Re: New wing tanks

    I am building a series 5 kit manufactured in 1994. The original tanks look fine but, because I haven't yet installed the tanks, I have ordered new ones. Because of the recent article about what fuel to use in a Rotax engine showing advantages and disadvantages of 100LL versus auto-fuel, I figure that with the newer tanks, it won't matter what I finally end up using. (see article in August 2019 Sport Aviation, page 120).

  6. #16
    Senior Member jiott's Avatar
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    Default Re: New wing tanks

    I would recommend calling the factory to find out when they started supplying the new tanks in the kits. If yours are the old ones, I personally would change them out to the new ones. Fuel system worries are one thing I don't want to have-its too critical. Just my 2 cents.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  7. #17
    Senior Member Av8r_Sed's Avatar
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    Default Re: New wing tanks

    My early 90’s vintage Denny Aerocraft tanks have only seen ethanol free and 100LL. They’re fine and I’ve had no trouble with them. Even the Kreem sloshing is in good shape. I wouldn’t be concerned with yours. Might want to check them for leaks though before you (re)cover the wings.
    -- Paul S
    Model III SN910
    582 IVO Med

  8. #18
    markwalker's Avatar
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    Default Re: New wing tanks

    I recently purchased an early 1990's kitfox 4 that has a little flaking around the tank necks. Will This continue if I only use only
    non-ethanol or 100 low lead or is it too late and the tanks need to be resealed or replaced?

  9. #19
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    Default Re: New wing tanks

    Mark

    I'm by no means an expert on the fuel tanks, so I won't even try and answer whether or not the tanks are usable. Given that there is some flaking, I think would warrant further inspection. Unless you can get a camera or borescope inside you really don't know what is happening inside. Have you pulled the finger strainers to check for flakes. Others who have had this problem can probably provide more insight on what to look for. Good luck.

    Rick

  10. #20
    markwalker's Avatar
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    Default Re: New wing tanks

    Thanks for the information!!!! I will do my due diligence with the tank inspection and plan to use 91 octane ethanol free unleaded for regular use and 100 LL when on trips if ethanol free is unavailable.

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