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Thread: Fuel System Mod

  1. #41
    Steve's Aircraft (Brian)'s Avatar
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    Here is a quick drawing I just made of a L/R/Both position valve....

    Click image for larger version. 

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    As you can see by the drawing, when the valve is in either Left or Right position the tanks are independent of each other. In the Both or off position, they are connected.

    On the CC headerless fuel system you are supposed to connect via a 1/4 inch tube the top port of the fuel gauge of both tanks thus creating an interconnect vent system. If you have this connection and you have enough fuel in the tanks and you are parked wing low on a slope the fuel in the upward tank could flow through the "vent" line and into the low tank until the fuel in the up tank empties past the top of the fuel gauge.......now does that make any sense....

    Brian.

  2. #42
    Darrel Starr's Avatar
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    SteveE, makes sense to me. Some fuel would come through the vent line with fully full tanks but soon the up side vent would be dry so the primary flow would come through the valve in the "both" position.
    Darrel
    Last edited by Darrel Starr; 02-01-2011 at 09:14 PM.

  3. #43
    mvivion's Avatar
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    Quote Originally Posted by Darrel Starr View Post
    The 1/4 inch diameter crossover tube is connected from the top of one gas gauge to the top of the other one. So except when the tanks are full, fuel doesn't flow through them. They are there in case one of the cap vents plug. The crossover tube in that case gives a second source of air to the tank with a plugged vent.
    Darrel
    You're missing the point, Darrel. If your right tank, for example, is say, 3/4 full, and your left tank is full, and you park on a left sloping spot....the fuel in that right tank will port from the right tank to the left, and thence overboard via the left tank vent.

    This is a characteristic of the Husky, which has an on-off fuel system. ANd, I think Mark's proposed solution is a good one. Don't know if you could get it "legal" except in Experimental, though.

    MTV

  4. #44
    bearsnack
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    CC's headerless STC is designed to be installed on an already built/airworthy airplane or a project. I think they ran that cross feed vent line aft to avoid the stock electrical in the right side wing root area. It may work better that way in 3 point and level flight, also?
    Last edited by bearsnack; 02-01-2011 at 08:37 PM. Reason: To avoid butchering the English language

  5. #45
    Gordon Misch's Avatar
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    Mike, Darrel has it exactly right - check his most recent post again, where he wrote: "Some fuel would come through the vent line with fully full tanks but soon the up side vent would be dry so the primary flow would come through the valve in the "both" position."
    Gordon

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  6. #46
    Taledrger's Avatar
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    Great insight guys. Thanks alot!!
    Bob D

  7. #47
    mike mcs repair's Avatar
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    Quote Originally Posted by mvivion View Post
    . ANd, I think Mark's proposed solution is a good one. Don't know if you could get it "legal" except in Experimental, though.

    MTV
    That's how we do them all, never had an issue....

  8. #48
    Beach Bum's Avatar
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    Quote Originally Posted by Taledrger View Post
    Decide to redo the interior on the L21 and install the CC fuel STC to get rid of the header tanks. She's all tore apart and ready to start reassembly as soon as I get the right tank back from doing the fitting mod.
    Any advise on the install? Do's don'ts, etc.
    Any examples of how to run the lines with L21 glass would also be appreciated.
    Good timing on the question Taledrger. I'm putting one in too and so far picked up the plans twice and put them back down. The instructions would be better if they included pictures of routing the fuel lines and of modifing the fuel selector. Can the fuel line be run behind the bulkhead to hide it from view? I'm referring to the location near the flap pulley.

  9. #49
    Steve's Aircraft (Brian)'s Avatar
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    Brittle

    That is exactly where I am going to put it on the airplane I am working on. If you look at Darrel's pictures posted at #29 previously on this thread you can see that is where his runs also.

    Brian.

  10. #50
    Taledrger's Avatar
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    Would like to run the line as in Darrel's example as well. We still have the battery in the original location so that will be close. Maybe it's time to move that too being we plan to move a good bit, if not all, the electrical to the dash.
    Just looking thru Darrel's album at other pics on the rebuild of his airplane. All I can say is "WOW" that thing is nice.
    Bob D

  11. #51
    Steve Pierce's Avatar
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    I did the mod on an L18C years ago. The junction for the rear header was placed behind the aft baggage wall, no problem. The rest of the lines ran as stock except the new front right line which was kinda a pain because all the stuff that was run through there. Not a big deal.
    Steve Pierce

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  12. #52

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    Am wondering if anyone has considered keeping the header tank for the left side but not the right, using the right side basically for cruise? Would save a little weight and keep one of the tanks out of the cabin. Would this configuration be covered under any of the STC's currently available? thanx for any info.

  13. #53

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    Quote Originally Posted by 68D View Post
    Am wondering if anyone has considered keeping the header tank for the left side but not the right, using the right side basically for cruise? Would save a little weight and keep one of the tanks out of the cabin. Would this configuration be covered under any of the STC's currently available? thanx for any info.

    Your best bet is to call CC and see what they say.

  14. #54

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    Quote Originally Posted by Brittle View Post
    Good timing on the question Taledrger. I'm putting one in too and so far picked up the plans twice and put them back down. The instructions would be better if they included pictures of routing the fuel lines and of modifing the fuel selector. Can the fuel line be run behind the bulkhead to hide it from view? I'm referring to the location near the flap pulley.
    I ran my line on my -12 behind the PA-14 cathedral brace but I don't have flaps.

  15. #55

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    one thing to think about is the fuel line running just behind the firewall? From the one i put in many years ago they had a beaded splice on the forward line to the selector valve i see in the pics AN fittings are used there the best but still think the stock header tank in the front is just as safe as a fuel line running across the back side of the firewall
    and as far as weight you are just talking about the weight of the header tank itself and remember no matter what system you can port the system with less than half tanks in a step turn on floats the header tank system takes longer !!
    Steve c

  16. #56
    AkPA/18's Avatar
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    Quote Originally Posted by supercub24a View Post
    o remember no matter what system you can port the system with less than half tanks in a step turn on floats the header tank system takes longer !!
    Steve c
    Hi Steve---are you sure?? I thought that was one of the advantages of having the both selector. Maybe I need to think about it some more.

    Thanks

    Mark
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  17. #57

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    you are correct if you have it on both my mistake!
    Steve c

  18. #58
    Taledrger's Avatar
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    Just a word of advise.... If your going to do this mod get a real professional to install the right tank forward outlet..... Anybody got a right side 18 gallon tank preferably with the outlet already installed or at least no fumes....
    Bob D

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