Fuel X Feed Question

[rgamurot 1]

When I sit at the gate with my APU running, I know it uses fuel from my #2 tank. But lets say I'm sitting at the gate and am suddenly delayed or have been running my APU for a long while, naturally I would use more fuel from that tank. But when I'm in the air, my #2 and #3 tanks are unbalanced. This doesn't set off any imbalance alarms but it does cause problems when I hit TANK/EGN. Since the X FEED valves are open, shouldn't the tanks automatically equalise or am I supposed to use the override pumps for this which I've been doing? Or is there another procedure that I don't know about?Ryan GamurotLucky to live Hawai'ihttp://www.precisionmanuals.com/images/forum/supporter.jpg

[Qavion 19]

"This doesn't set off any imbalance alarms but it does cause problems when I hit TANK/EGN."Ryan... Are you saying that you DO get alarms when you go to TANK/ENG? Note that there is a special warning in this configuration (i.e. and imbalances between inboard(2&3) and outboard (1&4) tanks of 2,720Kg)"Since the X FEED valves are open, shouldn't the tanks automatically equalise"No, fuel cannot be transferred from one tank to another (unless done by maintenance). XFEEDing is simply allowing any tank to feed any engine. If there was a serious imbalance during the final stages of Tank-To-Engine, and one tank is about to run dry (killing the respective engine) then you would reopen your crossfeeds and allow the other tanks to feed that engine.Rebalancing can be achieved by opening crossfeeds and switching off pumps in the lowest tank. Hope this helpsCheersQ>

[rgamurot 1]

Thanks Q. About the TANK/ENG alarm, when I reconfigure, the EICAS switches from TANK/ENG to X FEED CONFIG. I'm guessing this is due to the fact that there is more fuel in tank 3 than tank 2. Yet tank 2 is equal to tank 1 and 4 and ready to be reconfigured.As for the cross feeding, I thought it was like other systems where the tanks link up and will use gravity to move fuel from the lighter tank to the heavier one. PMDG wasn't kidding when they said it was complicated!Thanks again!Ryan GamurotLucky to live Hawai'ihttp://www.precisionmanuals.com/images/forum/supporter.jpg

[Qavion 19]

"I'm guessing this is due to the fact that there is more fuel in tank 3 than tank 2. Yet tank 2 is equal to tank 1 and 4 and ready to be reconfigured."I guess the easiest solution is to let both inboards drop below the outboard value before reconfiguring to TANK/ENG?Cheers.Q>Lucky to have visited Hawai'i (30+ times) :(

[rgamurot 1]

I'll try that. Thanks again. And feel free to drop me a line next time you visit O'ahu.Ryan GamurotLucky to live Hawai'ihttp://www.precisionmanuals.com/images/forum/supporter.jpg