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Thread: Fuel valve and bracket

  1. #1
    Senior Member Andy's Avatar
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    Default Fuel valve and bracket

    My FX-3 fuselage has a bracket that is obviously designed to support the top two holes of the fuel valve. After I removed the left middle side panel of my FX-3 I found that the relaxed position of the fuel valve is more than 1/4 inch aft of, and below, the bracket.

    It takes an unreasonable amount of force to align the valve mounting holes with the fuselage bracket. Are EX-3 builders instructed to mount the valve to this fuselage bracket or has the design been changed to support the valve only by the side panel?
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  2. #2
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    Default Re: Fuel valve and bracket

    809B0D78-4414-42A4-8AA8-F7A2C2229646.jpg

    Yup.

    Quote Originally Posted by Andy View Post
    My FX-3 fuselage has a bracket that is obviously designed to support the top two holes of the fuel valve. After I removed the left middle side panel of my FX-3 I found that the relaxed position of the fuel valve is more than 1/4 inch aft of, and below, the bracket.

    It takes an unreasonable amount of force to align the valve mounting holes with the fuselage bracket. Are EX-3 builders instructed to mount the valve to this fuselage bracket or has the design been changed to support the valve only by the side panel?
    Last edited by Daveembry; 10-24-2021 at 06:44 PM.
    Dave Embry
    "You only live once.......but if you do it right.........once is enough."..

  3. #3
    Senior Member ceslaw's Avatar
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    Default Re: Fuel valve and bracket

    Andy:

    I noticed the same thing on the EX2. The fuel line on the aft side that curves up and forward seems to be the culprit. My impression is that the tension is something we live with. I don't know if the EX3 has the same fuel line layout however.

    I had contemplated adding a standoff to divert the tension and make the holes align more naturally. Not sure it is necessary.

  4. #4
    Senior Member Andy's Avatar
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    Default Re: Fuel valve and bracket

    Thanks for the replies.

    I found a build photo that shows the fuel valve attached to the fuselage bracket and the hoses/tubes secured in the same positions that they are now. Either the tubes were pulled very tight when the valve was installed or something has changed. The force required to line up the valve with the bracket is unacceptable.

    It appears that the easiest way to get the valve to line up with the bracket will be replace the tube feeding the aft valve port with a longer one. That's the short tube between the T and the aft valve port.

    Can someone tell me the type/size and preferably a part number for this tube. Can the fittings be re-used? The plastic T seems to be the type type as the pitot/static fittings but the connection to the valve is metal.
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  5. #5
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    Default Re: Fuel valve and bracket

    The fuel tubing came in bulk for my kit and the builder cuts it to size. So I don't think there would be a P/N for the connecting tube.

    I'm sure there are builders that has some excess left over tubing. What is the OD & ID (not sure the EX-2 is the same as the FX-3) and the length needed?

    And yes the fittings can be reused. I'd have to look it up, but I believe there are different torque requirements for the plastic vs metal nuts.
    Last edited by aeroaddict; 10-25-2021 at 12:48 PM.
    Dan Arnold
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  6. #6
    Senior Member Andy's Avatar
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    Default Re: Fuel valve and bracket

    Quote Originally Posted by aeroaddict View Post
    The fuel tubing came in bulk for my kit and the builder cuts it to size. So I don't think there would be a P/N for the connecting tube.

    I'm sure there are builders that has some excess left over tubing. What is the OD & ID (not sure the EX-2 is the same as the FX-3) and the length needed?

    And yes the fittings can be reused. I'd have to look it up, but I believe there are different torque requirements for the plastic vs metal nuts.

    Thanks for the reply Dan.

    I found most of the answers by reading a couple of fuel system service bulletins.

    The tubing is 3/8 OD 1/4 ID with manufacturer's part number marking 660N-N.

    The metal compression fitting ferrule does not seem to be reusable but the nylon fitting parts may be. It seems be the same type of fitting as used in the pitot/static system and I have experience with those. It is the next size larger though.

    I'm putting together a list of what I need. All the specified Loctite supplies are available locally but I haven't found the tube or fittings yet.

    This whole sorry saga started because the prop control cable is defective.

  7. #7
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    Default Re: Fuel valve and bracket

    Before you order everything you might want to check alignment of the side panel and fuel selector cover panel for the new position.

    The only reason I can think of why your fuel selector is not attached to the fus bracket is that the FX-3 has a different configuration due to the throttle/prop linkage (or other stuff). And the FX-3 fuel selector position doesn't work with the original EX/FX-2 position. Just a guess on my part. But before I went to that effort I would check panel alignment, especially the smaller one, in the new fuel selector position.

    Just saying. I try not to swear, but if I went to that effort and then the side panel does line up, you might hear me yelling all the way down there in AZ.
    Last edited by aeroaddict; 10-25-2021 at 04:10 PM.
    Dan Arnold
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  8. #8
    Senior Member Andy's Avatar
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    Default Re: Fuel valve and bracket

    Quote Originally Posted by aeroaddict View Post
    The only reason I can think of why your fuel selector is not attached to the fus bracket is that the FX-3 has a different configuration due to the throttle/prop linkage (or other stuff). And the FX-3 fuel selector position doesn't work with the original EX/FX-2 position. Just a guess on my part.

    The reason that the valve is not attached to the fuselage bracket now is that I removed the valve sub panel and the center side panel to gain access to the prop control cable. That means the valve has to be free of the bracket as the top two screws go through the circular metal trim plate, the valve sub panel, the bracket, and then the valve. In an earlier post I included a photo of my aircraft on the factory production line showing the valve attached to the bracket after covering but before the panel was fitted.

    Dave also confirmed that the EX-3 build instructions show the valve attached to the bracket.

    You are right that I should line up the panels and see if the valve lines up with the sub panel and not with the bracket. I had intended to do that but was thinking the build photo showing the valve attached to the bracket would be sufficient.

    If someone from CubCrafters is reading this and knows FX-3 are intentionally built with the valve not attached to the fuselage bracket - please let me know.
    Last edited by Andy; 10-26-2021 at 06:59 AM.

  9. #9
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    Default Re: Fuel valve and bracket

    Guess I missed that. All I remember was the smaller fuel selector panel cover did not line up real well with the main side panel and selector during final install.
    Dan Arnold
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  10. #10
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    Default Re: Fuel valve and bracket

    Yes the valve is attached to the bracket on my EX3. The fact that yours is not is a serious head scratcher

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