Fuel Tanks Asymmetric use
I have a J430 G-PHYZ. I have noticed that even when the aircraft is flown in balance the fuel in the starboard wing tank seems to get used faster than the fuel in the port tank. The level in the sight gauges falls in the starboard tank until it is about 2 cms from the bottom of the gauge. The port tank then starts getting used. At all times there is sufficient flow from any one tank to easily meet the maximum engine consumption. Other J43o owners in the UK report the same effect. Is there any reason of explanation for this effect?
It only takes a tiny difference in air pressure between the 2 tanks for one tank to feed faster than the other. Maybe a difference in the airflow past the tank vents. Also a small amount of out of balance of the flight will cause the same effect.
We had the same concern and are still baffled by the physics of this, however when testing flows from both tanks into the header tank on the ground, both flowed evenly. We still experience asymmetric emptying after a flight and assume that the 5 litre header which is in our case fitted aft of the parcel shelf in the fuselage will always prevent fuel starvation occurring. We are also more aware of keeping the ball in the middle during flight. So, in summary, is this just a recognised fact of life for Jab owners?
Eureka! we have found an easy explanation for the occasional big difference in drainage from the wing tanks. After a recent intensive few hours of circuit training, the right hand tank was nearly empty and the left nearly full. It then dawned on us that we had been continuously doing left hand circuits, so the right hand tank was often higher than the left....hence preferential drainage. To prove the theory, we then did lots of right hand turns and hey presto....the tanks more or less equalised. Conclusion, as said above, it takes only small differences in flight patterns to affect the drainage, we are now happy that we will not run out of fuel in flight and probably will not normally be doing loads of turns one way only!