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Thread: Shut off valves on fuel tanks.

  1. #1
    Senior Member Kitfox Pilot's Avatar
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    Aug 2019
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    Default Shut off valves on fuel tanks.

    Do you recommend quarter turn shut off valves on main fuel tank lines? I see them on several planes but they are not mentioned in the build book. I assume they would stop fuel transfer from one tank to the other on a hill.
    Maybe just on one tank to stop hill transfer so you would always have one tank on if one forgot to turn the valves on?
    What's your opinion?
    Harlan and Susan Payne
    Sold Piper Archer
    Flying FarmFox STI Kitfox N61HP
    Rotax 915is, Airmaster prop
    https://www.youtube.com/channel/UC5A...oCVUP15G0uB-Yw

  2. #2
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    wales,ny
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    Default Re: Shut off valves on fuel tanks.

    Harlan, there is a thread on this somewhere if you search the forum. I added 2 wing tank to header inline fuel valves on my Series 5 years ago for several reasons. 1)As you mentioned, you need some way to stop fuel transfer from tank to tank on eneven parking ramps ( can't tell you how many times at fly ins that I see kitfoxes peeing unashamed, when no one is looking due to uneven park jobs). On my shutdown checklist , I always shut one of the valves then clip a "remove before flight" flag on my master switch to remind me to open it before next flight. As a matter of fact I do this when I put the airplane in the hangar now , in case I get a flat tire , as the fuel would pee out the low tank on the flat tire side, and cause a real fire hazard if I have my preheater running (thank you Eddie Forward). 2) inflight fuel balancing- as you will find as many others have when they start flying their new builds, fuel sometimes burns exclusively from one tank or the other, so you can have the left tank full and the right tank near empty. The valves allow me to balance fuel inflight (again I use the red flag system descibed above, whenever one is closed) 3) maintenance- there are times I want to isolate one tank from the other during inspection or maintenance. An example is when I check my low fuel warning system light every condition inspection. I used to have to drain all fuel to activate the light.
    If you proceed with this make sure during your before 1st flight fuel flow tests, you have sufficient flow. Bruce N199CL

  3. #3
    Senior Member Kitfox Pilot's Avatar
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    Default Re: Shut off valves on fuel tanks.

    Bruce, that all makes very good sense, thanks.

    And I will try to search up that old post on the subject.
    Harlan and Susan Payne
    Sold Piper Archer
    Flying FarmFox STI Kitfox N61HP
    Rotax 915is, Airmaster prop
    https://www.youtube.com/channel/UC5A...oCVUP15G0uB-Yw

  4. #4
    Senior Member 109JB's Avatar
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    Default Re: Shut off valves on fuel tanks.

    one thing to think about is header tank venting. Not sure on the newer models, but on my model 4 the header tank is vented to the right fuel tank. So there are some scenarios to consider.

    1. Right tank turned off - Fuel can still migrate from the left tank, through the header and into the right tank if the header vent is open. This would defeat one benefit of parking on non-level ramps

    2. Left tank turned off - Fuel can't migrate in this situation because the fuel in the left can't go anywhere as the only open port is the cap vent. The right tank can flow into the header, but can't get to the left tank, and since the vent in to the ight tank there is no migration tot he other tank.

    So, If I installed valves in the tanks, I would burn from the right (vented) first for a bit, then the left. The reason I say this is because if the right tank is full and fuel migrates from the left tank it has nowhere to go but out. If you are in a subtle crab, one cap vent works better than the other, or whatever else you can think of to create just a bit more pressure in the left tank, fuel is going to migrate and go out the right vent.

    When parked, turn off both tanks, or at least the left to prevent fuel migration.

    BTW, I plan to install valves in my model 4 when I get to that point.
    John Brannen
    Morris, IL
    Sonerai IIL (Single Seat)
    Kitfox 3/4 1050 - Rotax 582 (Back Flying and sold)
    Kitfox IV 1050 - Rotax 582 (sold)
    Kitfox IV 1200 Speedster - Rotax 912 UL (project)
    Piper Twin Comanche (Sold)
    Glasair 1 FT (Waiting to start)

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