Ul gas tank questions

Discussion in 'The light stuff area' started by ryanjames170, Sep 23, 2018.

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  1. Sep 23, 2018 #1

    ryanjames170

    ryanjames170

    ryanjames170

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    So I know it's limited to 5 us gallons but my question is,

    Is 5 gallons total cubic volume of the tank.

    Or is it 5 gallons of fuel plus expansion room.

    Or is it 5 gallons usable plus room fir expansion and a sump ie water trap or fuel at the bottom below the fuel pick up.
     
  2. Sep 23, 2018 #2

    pictsidhe

    pictsidhe

    pictsidhe

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    5 gallons total.
     
  3. Sep 23, 2018 #3

    mcrae0104

    mcrae0104

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    However much 1,155 in[SUP]3[/SUP] of gas expands at whatever altitude you can reach in a Pt. 103 craft, the FAA will not be able to measure your tank capacity until you land.
     
  4. Sep 23, 2018 #4

    pictsidhe

    pictsidhe

    pictsidhe

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    These two documents are almost all the regulation on 103s:

    AC103.7

    Appendix.
     
  5. Sep 23, 2018 #5

    cdlwingnut

    cdlwingnut

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    I would say as long as there is a sticker or other saying max capacity 5 gallons and when you put 5 gallons of gas in it it looks pretty much full you will be ok
     
  6. Sep 23, 2018 #6

    pictsidhe

    pictsidhe

    pictsidhe

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    Nope.
     
  7. Sep 23, 2018 #7

    pictsidhe

    pictsidhe

    pictsidhe

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    Unless they have some reason to want to bust you. You are probably OK with a '5 gallon' plastuic gas can. Those do take over 5 gallons, though. a pair of 2 gallon ones would be nearer the mark.
     
  8. Sep 23, 2018 #8

    TFF

    TFF

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    The standard has been fly on 5 and have 5 as baggage if you need to fly that far without access to fuel. If you need to be in the air that long in a 103 UL is the wrong tool In the box, and usage judgment is out of whack of the utility of a real UL.
     
  9. Sep 24, 2018 #9

    ryanjames170

    ryanjames170

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    I was more curious on the end of fuel expansion.
     
  10. Sep 24, 2018 #10

    pictsidhe

    pictsidhe

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    Extra Baggage fuel isn't allowed under 103 unless the total fuel carried is under 5 gallons. Though I'm sure some people do it. The rule is 5 gallons total fuel capacity, usable and unusable. If you don't want to leave some expansion space in your 4.9999999999 gallon tank by partially filling it, you can have a seperate expansion tank. Just as long as you can't somehow fill it while filling the tank. A vent hose and locating the expansion tank above the fuel tank sorts that out. Or, build your tank so that when full to the top of the filler, there's some expansion space above it.
    5 gallons should get you quite far.
     

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