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3-2-1-Now

X FEED CONFIG

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Hi,I had the memo > FUEL TANK/ENG so closed crossfeed valves 1 & 4. I then get the alert: >X FEED CONFIGAccording to Page 52 of Manual 11 (Aircraft Systems) the first memo occurs when MAIN 2 <= MAIN 1 & X-FEED 1 open, or MAIN 3 <= MAIN 4 and X-FEED 4 open.Is there a logic problem?Best regards,Robin.

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Did you also turn off the override pumps in main tanks 2&3 (see AOM 11-47)? This is just a guess.


Dan Downs KCRP

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Yes, I tried everything in every combination - no dice. :(Tank 3 < Tank 4, but Tank 2 > Tank 1. Is that sufficient?Best regards,Robin.

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I have the same issues. I'm doing everything according to the manual. For a while Ive been hitting the ECAS cancel button untill the fuel in tanks 2 and 3 are less than 1 and 4.


Kevin Hester,

 

Indianapolis, Indiana

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Guest Ryan Briggs

In order to satisfy the logic........Main tank 2 should be greater then Tank 1, and Main tank 3 should be greater then Tank 4so fuel should look something like this when you perform the followingMAIN 1=30.0MAIN 2=30.5MAIN 3=30.5MAIN 4=30.0Right around these fuel levels you should proceed to Shut the 2 Outboard Fuel Crossfeed Valves, this will isolate Tanks 1 and 4 to their respective engines and Keep the OVRD pumps Feeding 2 and 3, Fuel will now drain as it should, and the Fuel logic is satisfied. if that doesnt make sense, i can take a screenshot of the fuel setup a little later, I'm on a flight to Hong kong now so when i get to this stage of the flight i'll take a screen if anyone wants itin order to satisfy the logic though, Tank 2 must always be greater then Tank 1, and Tank 3 must always be greater then Tank 4, if you pass it and get the warning you should make sure the OVRD pumps and crossfeeds are on then shutoff Fuel pumps for 1 and 4, this will feed from tanks 2 and 3 only and rebalance the fuel levels across the wing

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Hi,The FUEL TANK->ENGINE message usually appears when the four main tnaks are all relatively equal in fuel level (typically around 51 tonnes or 51000Kg / 112436Lbs in the last third or so of the flight)Usually, all that is needed is to close the crossfeed valves first and turn OFF the two sets of OVD pumps adjacent MAIN TWO and THREE and thats it. Now, you have each tank feeding each engine.However, the X-FEED CONFIG warning can occur if you have unbalanced fuel levels.I have occasionally encountered, say 12.8 tonnes in TANK ONE, 13.7 tonnes in TANK TWO, 13.9 tonnes in TANK THREE and 11.8 tonnes in TANK FOUR.By keeping an eye on the fuel, you can "level up" the fuel by turning off the FUEL PUMP of the tank with the lowest level of fuel until the next nearest lowest fuel level equalises with it. Then, do the same with the lowest of the remaining two fuel tank levels and wait for the last tank to level out until all four tanks are roughly equal in fuel level. Make sure you leave the crossfeeds ON while you do this.This is a rather an oversimplified explanation but by good use of the crossfeeding system, you can equalise the tanks up and this will usually clear any CONFIG warning.Hope this is helpful,cheers,Lee


Lee James
Senior Captain
Events Manager

British Airways Virtual
Pilot of SPEEDBIRD 9 DELTA VICTOR (BAW9DV)

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Starting the APU early can cause the fuel to be slightly unbalanced causing the EICAS caution after going tank to Engine. If for whatever reason I have left the APU running on the ground for a while, once in cruise I always check the fuel synoptic to ensure 'both' inner tanks are equal or below the outer tanks before going Tank to engine. This may mean holding off reconfiguring the fuel pumps for a few minutes after I get the prompt.Rob


Rob Prest

 

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I got the same symptom yesterday KMEM-KSEA 744F (getting ready for the FDX MD11), I ran the APU longer than usual and the uneven 3&4 levels caused the xfeed message. I took the easy route by cancelling the alarm. At least now I understand what's happening. thanks Rob.


Dan Downs KCRP

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Hi,In my case, Tank 1 > Tank 2, but Tank 3 > Tank 4.Is it really necessary to mess around with cross-feeding when the tanks are all within 800 lbs of each other and you get the Tank/Eng memo?I did have a fuel deficit in Tank 2 due to APU usage, but the transfer from Center tank to Tank 2 just about balanced it out again (intentional design?).Best regards,Robin.

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Hi Robin,>>Is it really necessary to mess around with cross-feeding when the tanks are all within 800 lbs of each other and you get the Tank/Eng memo? I did have a fuel deficit in Tank 2 due to APU usage, but thetransfer from Center tank to Tank 2 just about balanced it out again (intentional design?).<


Lee James
Senior Captain
Events Manager

British Airways Virtual
Pilot of SPEEDBIRD 9 DELTA VICTOR (BAW9DV)

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So basically I should have balanced up Tank 2 to be greater than Tank 1, then configured Tank/Eng?I figured with the memo appearing, the system felt that wasn't required...Best regards,Robin.

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Robin,>>So basically I should have balanced up Tank 2 to be greater than Tank 1, then configured Tank/Eng?<ENGINE prompt point - but your close to it. So after you have balanced up tanks 2 and 3, balance up tanks 1 and 4 by shutting off the pumps on the tank with the lowest fuel level - and allow the other tank to drain down to match it.Now simply switch ON all pumps and OVRD pumps and leave the crossfeeds OPEN until you get the TANK->ENGINE prompt. Then close the crossfeeds first and finally shut off all OVRD pumps, leaving one set of pumps on for each of the four engines - the final fuel configuration for the remainder of the flight.You can still use this method for rebalancing tanks where the fuel load is so out of balance that you need to sort it out. Just do it one tank at a time.Hope this helps,cheers,Lee


Lee James
Senior Captain
Events Manager

British Airways Virtual
Pilot of SPEEDBIRD 9 DELTA VICTOR (BAW9DV)

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