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Header tank

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Posted

Hate to bring this up because it has been hashed out before but how do most of you vent your header tank?

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Posted

Mine vents to a fitting on the right wing tank. 

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Posted

Avids usually vented out through a tube going through the skylight.  Kitfoxes idea is probably better, cause its always working and you don't need to think about it.  With my Avid, I had to put a valve in the line going to the vent or suction would pull fuel out while in flight.  Others have had the same experience.  I vent my header tank before each flight, and then the valve stays closed.  If I open it, I immediately see fuel being sucked out.  (and even at the lower prices we pay for fuel these days, that sucks :lmao:)   JImChuk

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Posted

Mine was thru the skylight as probably the Avids. I am going to install a valve in the vent lie as a precaution since both cap are vented. Don't really want to drill any more holes in the plastic tanks if can be avoided. Also thought about a one way valve. But KISS is always better. Thanks!

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Posted

You don't need to vent the header tank if you have a line from each tank running to it, it will vent to which ever tank is lowest on fuel.  I had mine with the candy cane vent that Avid showed to use and it dumped fuel on the skylight and ruined it the night after I had just put a new skylight and windshield in.  

I have the 2 main tanks running into it and if the system is completely empty open both valves and fill one wing tank.  The header will vent into the empty tank. I always start and take off with both tanks on, then in flight I will shut off one tank or the other.  

:BC:

 

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Posted

I had never considered running without a vent line but the self venting theory makes a lot of sense. The only real advantage of a vent line is (with a see through line) is to see when the wing tanks are empty and landing should be a priority:o

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Posted

I had never considered running without a vent line but the self venting theory makes a lot of sense. The only real advantage of a vent line is (with a see through line) is to see when the wing tanks are empty and landing should be a priority:o

the lines from the tank to the header are clear.  It is pretty easy to tell if fuel is flowing through them or not.  You can also se the air bubbles in the lines when the header tank is venting and filling.  Once it is full, there is really no way to get air into the header tank unless you run both wing tanks completely dry.  

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Posted (edited)

My theory is once the header tank is full then a vent isn't really needed. But to initially get the header tank full it has to be vented some way, so I put a valve in the vent line. It can be open or closed depending on what the situation calls for. I have the candy cane thru the top windscreen also.

Edited by Allen Sutphin

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Posted

 If you have 2 wing tanks flowing into the header tank, it will vent from one to the other.  This is not theory, its a fact :lol:  in the 10 yrs I have been flying my avid like this I have never had an issue with it.

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Posted

My header is not vented, the wing fuel flows into it, and it has lots of headspace to collect air, which I expel prior to every flight. I open the valve on the top and drain the fuel onto the ground, thus assuring that the air is let out first.

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Posted (edited)

Providing you have both wing tank valves open. One could look at the header tank as a 1 1/2 gal bulge in the fuel line, same logic as a common plastic fuel filter only bigger. No need to vent a fuel filter so the header tank would just be a big filter. This is kind of an oddball comparison but seems logical. I have a valve in each wing tank so running with both valves open it would work ok.

Edited by Allen Sutphin
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Posted

While on the subject of header tanks,

i put 5 gallons of gas in the header tank for some taxi and adjustments yesterday for the first time, and has anyone had the nuts that inserted into the plastic tank weep gas? The bottom right side one, Not leaking bad but leaking bad enough. Hahahahaaaa  

Anyone have this problem and anyone have a fix by chance. 

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Posted

I did. Warm and cold temps cause the tank to expand and contract a smidge. I used plenty of ukum pucky on the threads. Worked!

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Posted

That works for the center where threads r, on mine after i took it apart, the gas also weeps around the nut as it is little loose in the plastic. Thinking ill use some permetex aviation seal like u and Leni mentioned and also a small thin butle rubber gasket,  i think it got a little to long of a bolt screwed into it and opened the back of hole up some? 

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Posted

Be careful of overtigthening in the plastic.

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Posted

Or too long of a bolt/screw 

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