Fuel usage from one tank and not the other

[deadstick]

After some info regarding the fuel system in the Gazelle, I and a friend fly 2 different gazelles and one will feed from the port tank and the other feeds from the STBD, both suck down to around 5-7-7 litres before they start feeding from the other tank. What I want to know is- is this normal for the type and what would cause it? balnced flight is maintained and I am not sure if its effected by the boost pump or not.

 

 

[Guest Wigg]

When this first happened with our Gazelle thought life was soon going to finish but found out it has always done this. It is a bit disconcerting at first but live with it now . Cheers John

 

 

[facthunter]

Uneven.

 

This appears to be quite common with Gazelle's. I am inclined to put a lot of it down to flying with slight unbalance. It doesn't take much. I have seen a maximum of about half a tank difference, and never inclined to totally be happy with it. This has been discussed before and a link to it might be a good idea. Nev

 

 

[Ultralights]

Jabiru 170s, well, our schools one does the same. actually its more common than not, i cant remeber any aircraft i have flown that drained both tanks evenly, unless you turn one tank off, and drain for 1 for 15 mins then regularly change tanks. but im not a fan of closing any tanks off inflight, unless your flying something with 4 tanks etc.

 

 

[Neil_S]

Hi Deadstick,

 

Yup - happens all the time in my Gazelle. Starboard tank first, then port. Has always done so. Our best guess is uneven venting, but it doesn't matter as they cross-feed anyway.

 

A friend has the same thing happen in his Jab 160, but the other way round, so I don't think it is confined to Gazelles by any means.

 

Cheers

 

Neil

 

 

[barandbrew]

HI Deadstick

 

I have had this problem with my Gazelle since I purchased it 6 years ago.

 

On the weekend we did a 100 hr service I mentioned this to my LAME an told him that I found when swaping the fuel caps over it reversed the drain. I had been expermenting with the position of the vents to air flow as it is obviously a pressure problem on inspection he found that the spring metal that holds the caps secure is made of different material one has a strong spring action the other weak. We adjusted this and I hope it will cure my problem . I will let you know when next I fly.

 

Hope this helps as it has been bugging me since I bought the aircraft

 

John

 

 

[barandbrew]

HI Deadstick

 

Flew yesterday with the adjusted caps and the fuel drain is nearly even Hope this helps

 

Regards

 

John:thumb_up:

 

 

[rk67]

breathers

 

first thing I would do is check breathers, our gazelle feeds evenly

 

 

[deadstick]

balance

 

Thanks for the reply's, I am certain it has to do with balance after testing yesterday on a 1.5 hr flight I noticed the aircraft is out of balance it wants to roll left and slip so every time I was looking around when my eyes were back inside it would be slightly out.

 

 

[Keith W]

My Gazellewill use nearly all the fuel from the port tank before it starts taking fuel from the starboard tank, also I get fuel streaks on the starboard wing, not much but enough to be a nuisance, removed the filler and checked the seal everything ok, only thing I can think of is a bit of a vacuum sucking some fuel out through the breather or the tank some how getting pressurised enough to force fuel out open to suggestions thanks Keith.

 

 

[frank marriott]

"stand on the empty tank" hold about half a ball out and wait, the fuel will gradually balance. Standard practise even in a C208 which has a maximum listed balance limitation [with floats anyway]

 

 

[OZJohn]

I find it is usually to do with the vents. One is in a slightly different pressure area than the other.

 

John.

 

 

[biggles]

I find it is usually to do with the vents. One is in a slightly different pressure area than the other.John.

With the current Jab set-up , the vent holes are forward facing, therefore subjected to the same degree of air pressure .... Bob

 

 

[Neil_S]

My Gazellewill use nearly all the fuel from the port tank before it starts taking fuel from the starboard tank, also I get fuel streaks on the starboard wing, not much but enough to be a nuisance, removed the filler and checked the seal everything ok, only thing I can think of is a bit of a vacuum sucking some fuel out through the breather or the tank some how getting pressurised enough to force fuel out open to suggestions thanks Keith.

Hi Keith,

 

Our Gazelle did/does exactly the same. As noted previously on this thread we guessed slightly different venting, but as it was never a problem we did not stress about it.

 

Cheers,

 

Neil

 

 

[Pearo]

Cessan 172/182 is the same. I am only new to the game though. Put a heavy on one side and a light on the other get the same problem. Do circuits get the same problem. Switch tanks no issues with fuel starvation. I am guessing this is not unique to the gazelle.

 

 

[Sav 4352]

My Savannah was the same, seemed to depend on the crosswind, put a tap on both tank and now use the left then the right, problem solved.

 

 

[Keith W]

Thanks for the replies every body, I'm not that worried about the uneven fuel drain it's the slight dry fuel streaks down the wing that I don't like, the only place I can think of where it's coming from is out of the vent, wether it's being sucked out or pushed out I don't know, I thought it might be related that the side that drained last had the fuel s

 

 

[facthunter]

My experience with school aircraft, the variation seems to be related mostly to who last flew it. If you have a full tank for whatever reason it's close to venting fuel out. (Unless you have a very well designed vent system.) Nev

 

 

[Guernsey]

Not sure about some aircraft but it does remind me of my marriage (55 yrs), Sometimes my wife vents her anger and some times I vent mine, but it all seems to balance out in the end and we seem to fly along quite nicely. .

 

Well balanced Alan.

 

 

[biggles]

Not sure about some aircraft but it does remind me of my marriage (55 yrs), Sometimes my wife vents her anger and some times I vent mine, but it all seems to balance out in the end and we seem to fly along quite nicely. .Well balanced Alan.

Yeah Alan , I know a bloke on this site that is 'well balanced' also , he has a chip on both shoulders ..... Bob