Fuel tanks unequal feed

[Relfy]

Damn JR, sounds like you just need to go and get urself a good old fashion calibration there mate! ;)

 

 

[jetjr]

I agree, do you know somewhere I can have it done?

 

Point being is what we percieve as level may not be that good, and Jabs seem very sensitive to flying out of level and fuel feed evenly

 

JR

 

 

[facthunter]

Inbalance in Gazelle

 

Certainly happens.. Nev

 

 

[Guest Qwerty]

One way valves will not stop the unequal use but they would stop fuel venting overboard due crossfeeding.

 

I have not put much thought into it but I think that Yenn's cross-over type vents could be made to work, care would be needed in their design to avoid setting up a siphon and venting fuel overboard anyway.

 

 

[compsci]

I have tried turning off the switch for the right wing tank and leaving the left wing tank switch on. I now am getting reasonably equal flow from both tanks. I assume that fuel from the right wing tank is crossing over to the left wing tank.

 

 

[Guest Decca]

Hi David. Compsci could be correct in his terminology in that "switching" from one tank to another may be a mechanical function of manually selecting a valve from one or both fuel tanks to an engine.

 

Larger aircraft certainly have, eg, electrically controlled crossfeed valves, but there is little difference between manually or electrically selecting fuel tank selection valves when it comes to terminology.

 

Regards, Decca.

 

 

[compsci]

David,

 

I did, indeed, mean a mechanical switch. I owned a retractable Piper Saratoga before

 

I bought my J230. There is a significant difference, in the U.S., between a FAA certified aircraft and the consensus standard LSA aircraft. LSA aircraft are new and allow design and construction practices that would be unacceptable in FAA certified aircraft. I am learning to live (I hope) with these limitations.

 

 

[facthunter]

Fuel tank selection in flight.

 

I have a couple of rules I apply to this sort of thing.

 

1. I like to land with BOTH tanks ON. and as even as possible.

 

2. IF I am fiddling with fuel selection, I try to be at height above a piece of ground that is suitable for landing. IF you elect to run a tank to even it up, you should prove the fuel flow capabilities of it before you set off on a trip where the fuel from that tank is necessary. as there may be a restriction causing the uneven readings. Mostly it is flying unbalanced that causes it but you should be sure. Nev

 

 

[jetjr]

Firstly Factory made Jabirus dont have the ability to isolate one tank from the other. Its because pilots can fiddle with them and accidently end up with one tank full and one empty, possibly running out of fuel or could could make the AC perform poorly in case of spins etc. Im not sure but dont think the AC were tested for compliance in this unbalanced fuel format.

 

In older ones or homebuilts the taps up near the tanks can isolate each tank.

 

When the guages are reading unlevel, and you turn one of the tanks off, the guages read level after just a few minutes. I think this unlevel reading is an indication error not the real level in each tank.

 

If a tank was turned off for a significant time and both tanks were still feeding equally this means the tap isnt working. These taps are 2 in 1 out so theres no way fuel can exit a tank unless nearly full and seriously unlevel flight

 

Seeing as these taps arent even fitted in factory models im not sure what the concern is.

 

I too dont like to play with these taps in flight, mine are marked "for emergency and maintenence use only, DO NOT USE IN FLIGHT"

 

Other point is Most Jabs now have header tanks with ~10l in it so wont run out for maybe 20 min flight time even if you turn both taps off.

 

 

[compsci]

Jetjr,

 

US built J230 have a mechanical shut-off switch for each wing tank and a third switch by the brake for total fuel shut-off. The "taps" are working. I believe that

 

there is a separate cross feed between the two tanks that allows the condition that I described.

 

Compsi

 

 

[jetjr]

Yes thats what they used to have here too.

 

If you look at the fuel plumbing diagram, these switches are the only way out of the tank, unless its overhead via breather

 

To do what you indicate a fuel line is crossed over somewhere. This needs checking

 

Its in the tech manual on the website pg 121

 

JR

 

 

[compsci]

Jetjr,

 

I did look at that diagram. There are differences with my (US ) J230.

 

My J230 has air breathers on the winglets. I have Queried Jabiru USA

 

about problem and will post their answer.