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Thread: Leaking wing tanks.

  1. #1

    Join Date
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    Default Leaking wing tanks.

    Hi all.. I have a kitfox 3 with 6 gallon aluminum wing tanks.. yes and they both leak. I've read some of the posts on hear but I'm still not sure how to proceed.. or where to buy replacements. Any thoughts? Thanks in advance..

  2. #2

    Join Date
    Jan 2018
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    Vernon, BC
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    Default Re: Leaking wing tanks.

    the RV homebuilts have owner made alu tanks, it's not impossible to take that project on .. I don't know if they have a suspension system to allow for the wing twist that the KF building technique imparts on the tanks ...
    given the warning of no ethanol in the 'plastic' tanks that are available for the KF models, like why go ahead with that option, I find it odd that the KF homebuilders have avoided solving the suspension problem for going with alu tanks ...
    I was lucky, a local RV builder (and so much more) lead me through building a new alu header tank, easier because it is all flat surfaces ... why not make 4 x 5gal tanks in alu, should provide lots of room for suspension ...

  3. #3
    Super Moderator Av8r3400's Avatar
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    Default Re: Leaking wing tanks.

    "Suspending" the tanks is not possible because the tanks are structural to the wing in the Kitfox design. The tanks act as the drag tubes in the first rib bay of the wing.

    To the original poster, there are or were until recently, at least a couple of people making ethanol resistant, fiberglass tanks for Avid Flyers, which would be "close enough" to use in the early model Kitfoxes. Maybe Avidflyer will chime in, this is more of his area of expertise.
    Av8r3400
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  4. #4

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    Sep 2018
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    Cool Re: Leaking wing tanks.

    What's the best way to remove the tanks? That bay is covered with 1/8 inch plywood, and I think that's what gives the wing strength. The tank is held in with rivets on the rear spar and silicon on the front spar. At least that's what the build book shows.
    Also does anyone know who might make them? I don't think I want to make one myself.

  5. #5
    Senior Member
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    Default Re: Leaking wing tanks.

    I did see on the Kitfox facebook site that someone in Europe had a set of early 6 gallon Kitfox fiberglass tanks for sale. His name is Georgi Georgiev and he posted on December 9. One has a small crack, $300 for the pair. Shipping would kill, but may not be that bad considering his asking price. I sloshed aluminum tanks on an Avid Flyer once and they held for a while, but started leaking later. JImChuk

    PS I've wondered if one was to fiberglass over the aluminum, kind of use it for a left in place mold if that would work. It might....

  6. #6

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    Default Re: Leaking wing tanks.

    pity that the early KF / Avid models placed so much emphasis on keeping the weight down, then combined with wanting the wing fold feature, the result is too much flexing in the first two bays - question, did the 13gal tank option only come out for the model 4 wing? is the 4 wing structure built stronger in this section?

    adding some sleeving to the wing spars past this section might replace the cross bracing, in combination with heavier cross bracing mid-span .. oh, best I shut up, I'm not a structures guy .. tip tanks? oops, nice CoG positioning but different loading on the wing ...

    some day I expect to be needing to replace the original model 4 tanks, not looking forward to that task, and hoping there will be a new replacement tank manufacturer willing to ignore the liability issues of this industry that has constrained progress for decades

    BTW, what is the current tank solution in the newest kits? can it be used in early model 4 wings?

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

    My Model III has factory 13 gal fiberglass tanks (not Ethanol safe). They're still holding fine since I've always used non-Ethanol gas (thanks Wisconsin!).
    -- Paul S
    Model III SN910
    582 IVO Med

  8. #8
    Administrator DesertFox4's Avatar
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    Default Re: Leaking wing tanks.

    My first Kitfox, a model 3, had one 13 gallon tank in the right wing and a 6 gallon tank in the left. Both fiberglass and neither ever leaked.


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  9. #9
    Senior Member
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    Default Re: Leaking wing tanks.

    Kitfox service letter # 10 dealt with replacing aluminum tanks with fiberglass tanks. The first Kitfox 3 I considered buying had been built with aluminum tanks, and they had been replaced with fiberglass ones. One thing to consider is sometimes these planes were built many years after they were bought, and so sometimes the new and improved things show up in older models even though those improvements weren't available when the kit was first bought. My understanding is that all kitfoxes after the Kitfox 3 can use the same tanks, except for maybe the STI wing.

  10. #10

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    Feb 2019
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    Stockton Ut
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    Default Re: Leaking wing tanks.

    Haven't finished the repair yet but I have a model 1 with a 6 gallon aluminum tank in the right wing. I cut the bottom out of the tank and fabbed a new cover plate that will be riveted in place after smearing a lot of proseal around all the welded joints20190705_175627.jpg

    The above pic shows how I cut the bottom out. I have a plate that I fabricated with countersunk holes for the same kind of pop rivets vans uses on their fuel tanks. I did clean out the sloshing compound that was flaking off. Obviously no data on how well it will work yet but that's the direction I'm going.

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