Fuel Imbalance / Fuel logic problem

[Guest glt106]

Hi folks, One question, How can it be that the n

[Guest Phoenix5]

Hi Patrick,The only fuel imbalance I have seen was with the tanks associated with engine 1, due to the APU taking the fuel.A few minutes with cross feed rectified the situation. I have not tried shutting the engines down in flight but I will with my next long haul, and see what happens.Thank you for bringing this to our attention.

[Guest glt106]

Oh Norman you're right! The APU!I never switched it off....shame on me! But still the engines dont shut down when switching the pumps off and still they're using fuel they actually can't get...normally! ;)I'll see what happens with the APU off now... :))

[Guest Phoenix5]

Patrick,I am happy to let Norman take the credit for this one, but if you ever get us mixed up again, the easy way to remember who is who... I am the good looking one. :-) regards,

[Guest Steve Keating]

>Oh Norman you're right! The APU!>I never switched it off....shame on me! >But still the engines dont shut down when switching the pumps>off and still they're using fuel they actually can't>get...normally! ;)Switching the electric driven boost pumps off(situated inside the fuel tanks and producing approx 25-35 psi.) should not cause an engine flame out, the aeroplane would never be certified (total loss of electrical power?) if it did.The Main Engine Control unit or the Fuel Control Unit, depending on the engine manufacturer, contains two egine driven pumps, a medium pressure, approx 160psi, and a high pressure, approx 2000psi, as long as the engine is turning these will supply positive feed to the engines by sucking the fuel out of the tanks. There are probably altitude and performance restrictions in the event of a loss of boost pumps but as I'm not familiar with the T7 or the GE90 I can't quote figures or procedures.Anyway from what you say about the engine continuing to run it sounds like PSS got it right again.Steve

[Guest glt106]

I'm Sorry for the mixed Name thing ;)Seems if youre right didnt thought of the low/high pressure engine driven pumps!So it seems i have to should follow the procedures, switch of the apu and be glad PSS did such a great Aircraft :) :) [/url