L2 Fuel imbalance

[n6346m]

I have noticed that lately the fuel has been burning unevenly in my wing tanks in flight. I have never had this problem before, but lately after about an hour's flight, the right tank has significantly less fuel in it than the left tank. I checked the fuel cap vents and even switched them. The airplane flies perfectly straight hands off so I don't think it's a trim problem. Since the tanks are interconnected and have no separate fuel shut offs they should drain evenly. Before I take things apart, can anyone tell me if there are "finger" strainers in the tank. If there are strainers, are there four of them, two each for the forward outlets and the aft outlets and could that be the problem? Should I even worry?

[Ragwing nut]

Re: L2 Fuel imbalance

I have noticed that lately the fuel has been burning unevenly in my wing tanks in flight. I have never had this problem before, but lately after about an hour's flight, the right tank has significantly less fuel in it than the left tank. I checked the fuel cap vents and even switched them. The airplane flies perfectly straight hands off so I don't think it's a trim problem. Since the tanks are interconnected and have no separate fuel shut offs they should drain evenly. Before I take things apart, can anyone tell me if there are "finger" strainers in the tank. If there are strainers, are there four of them, two each for the forward outlets and the aft outlets and could that be the problem? Should I even worry?

Yes there are strainers in the tanks. Are you doing a lot of touch and go's with a left hand pattern?

[n6346m]

Re: L2 Fuel imbalance

Yes there are strainers in the tanks. Are you doing a lot of touch and go's with a left hand pattern?

Yes I have.

[Ragwing nut]

Re: L2 Fuel imbalance

The issue is when you make a left turn, you are increasing the head pressure on the right tank causing it too feed faster than the left. Left tank does not feed uphill very well. if all you are doing is making left turns, it will naturally feed from the right tank first.

[Hank Jarrett]

Re: L2 Fuel imbalance

Are you sure you don't mean slips instead of turns? If the turns are coordinated there shouldn't be any difference in pressure head between the tanks.
Hank

[Len Petterson]

Re: L2 Fuel imbalance

Long time ago I reed a storry about a DC3 what was parked on a runway with a side sloop overnight and the tank cross feed so the higher tank was almost empthy, resulting in a crach as one engine quit on take off. The fuelvalve was left on both!
The left hand circuit theory sounds very likly, remember what fluids will always find its own level nomatter what if it is allowed to or not, through pipeing in tanks etc. Just the law of nature, influenced by such trivial things as centrigual force, gravety, obstruction too flow, like an orfices and strainers acting like orfice,becuase of dirt etc, will slow down the flowrate, and can make the engine go quiet.
Len

[Ragwing nut]

Re: L2 Fuel imbalance

Are you sure you don't mean slips instead of turns? If the turns are coordinated there shouldn't be any difference in pressure head between the tanks.
Hank

If the tanks are not full fuel in the left tank will run away from the port in a left hand turn, right side will run towards. Most people don't and can't maintain perfect coordinated turns in light aircraft unless weather is perfect outside. You also have a crossover vent on the L-2 that could allow fuel to pass as well. Slips would also cause the imbalance but L-2's don't have to be slipped due to their extra weight and the wing cut out at the greenhouse, and don't have a tendency to float like the "B" does.

[Forrest Barber]

Re: L2 Fuel imbalance

Try her straight & level , smooth air , left and right turns on turn arounds. THEN if it still happens , light air pressure in reverse into the system , measure the air pressure out at the caps, keep at it , it should balance out.
B Models do not "float" ; they "fly" ; the pilot is using too high an airspeed.