Fuel Flow problem.

[KFA]

I agree with Morph on this one. The moment the header has an open vent and you get some sort of restriction between the tank and the header, then a vacuum will not be created and the header will fill with air. I personally rather like the idea that a vacuum could be created when there is a restriction in the lines. Another problem with the vent to the tanks is that when the tanks are full and you turn the fuel taps off the fuel simply runs through the vent line back to the header and you effectively have not cut the fuel untill it drains to such a point that it does not suck the fuel from the vent anymore. Because of the dihedral of the BB wing the vent line will never be at the highest point in the tank. I see that on the kitfox they have elimated this problem by running both tanks in the header behind the seat, vent it to the right tank and then only have one fuel selector in the middel console that turns the fuel on or off between the header and the engine. This solves the vent problem up to a point but you now do not have the option to manage your fuel seperately like on the BB.

[Oupa-G]

When you use the header tank with a fuel injection system you want the system to breath .In the Bosvark the breather goes to the neck of the fuel filler only then it is a real breather. When you fly the pitot pressure on the fuel cap will pressurise the whole system and any air in the system will breath to the top . When the fuel pumps purge the line the pressure of the pumps will push the fuel back in to the tanks and you can physically see it. All well designed fuel systems breath to the highest point that is normally the fuel filler neck. With a Bushbaby with di-hedral that is then exactly what happens. The drain on the header tank I can operate from the cabin. I feel that if you have to do a forced landing because of engine problems and it is an inevitable deadstick then time permitting I would close both wing tanks and open the header tank so that there is the least amount of fuel in the passenger compartment.


Cheers Oupa-G

[Morph]

The drain on the header tank I can operate from the cabin. I feel that if you have to do a forced landing because of engine problems and it is an inevitable deadstick then time permitting I would close both wing tanks and open the header tank so that there is the least amount of fuel in the passenger compartment.

Oupa G, in my case, with the header not being vented, closing the fuel taps will stop fuel from flowing out of the header tank, even if the drain tap is open. I need to open one of the fuel taps before draining fuel from the header to look for water during pre-flight.

[Boet]

Storm in a teacup. I never fit aux electric pumps. Nor do I fit header tanks. Two petrol pipes from the tanks, via a strainer INSIDE the tank, (See pic), through 2 taps, and into a T-piece behind the panel, to a nice big filter and a petrol strainer, and on to the engine. 912 gets a cross-piece between the carbs, with a back-flow to the tank in use. To get the petrol to flow, on a new plane, first fill-up, open BOTH taps, and lift the tail up, if it is a taily. NEVER had a problem. Switch tanks carry on.Fly. Smaaaail. On both tanks one always drains faster than the other. Dunno why, but they always does. Gentlemen, my advice is: KEEP IT SIMPLE, KEEP IT BASIC. Fly safe.

[Boet]

Jaaaaa OK, Oupa, I know I will need a header tank for the Bee Em. I`ve got one.

[KFA]

The header is going to become mandatory so better start fitting them Boet Daar is 'n goeie rede vir hom, is nie daar vir 'n ornament nie

[Oupa-G]

If you come in to land and when you sideslip the header tank as a serious function. In the Citation wing there is a header tank within the main tank the return fuel to the tank drives an automotive fuel pump that is a pump no moving parts that with the negative pressure in the venturi pump pumps fuel to the header tank the header tank then overflows into the main tank. The reason for that is to secure fuel flow under all conditions turbulence side slipping etc etc the header tank in the Bushbaby has the same function. The big boys are sometimes complicated but they are well engineered. For fuel flow I want the best engineering possible. "The saying goes it takes two days to design a system, but it takes two years to simplify the design."



Cheers Oupa-G

[Mogas]

There is nothing complicated about a header tank.
On the Bushbaby, Explorer and Safari it forms part of the type accepted build standard.
It has been debated many times but in a nutshell here are the 2 main reasons again:
1. Assures fuel delivery to the engine when there is a low fuel load in the wings.
2. If correctly installed it forms a perfect water/sediment trap as it will be in the lowest part of the fuel system.
Mogas

[Karamba]

Does this mean that those without headertanks are flying illegally?

[KFA]

Not yet but you are playing with fire. It's adviseable

[Boet]

Jawohl herr Oberst.

[Andrew Conroy]

I also have a simmilar problem /situation on my Zenair 701 it always favours the right hand tank.Boets explanation seems very logical to me.I removed my header tank (keep it simple) after 2 engine outs due to fuel starvation , tanks full but managed to drain header tank (long story) .So now I have the 2 tanks in the wing joined with a T piece and always fly with both open and so far (60 hr) no problem. I do find though the right hand tank is always more empty than the left sometimes as much as 30l. Do I have a problem I dont know about yet ????

[German]

My previous Tecnam and the one that I now have also both emptied the left tank first. I think it is because of more propwash over the left wing.They only have a Tpiece and no header tank.I normally close the left and only fly on the right except for take off and so on.

[justin.schoeman]

My previous Tecnam and the one that I now have also both emptied the left tank first. I think it is because of more propwash over the left wing.They only have a Tpiece and no header tank.I normally close the left and only fly on the right except for take off and so on.

Tecnam is plumbed a little differently from most.Fuel return line goes only to the right hand tank, so it will always fill up a little in operation.

[German]

My previous Tecnam and the one that I now have also both emptied the left tank first. I think it is because of more propwash over the left wing.They only have a Tpiece and no header tank.I normally close the left and only fly on the right except for take off and so on.

Tecnam is plumbed a little differently from most.Fuel return line goes only to the right hand tank, so it will always fill up a little in operation.

Never had a fuel return