scandinavian13

>FUEL TANK/ENG

51 posts in this topic

6 hours ago, scandinavian13 said:

There's some background logic to the guarded switches too. They're guarded for a reason, though I can't recall off the top of my head at the moment.

John or Alex will no doubt put more flesh on the bones, but the short reason is that crossfeeds 2 and 3 are managed by the Fuel System Management Cards (FMSC). They automatically open/close depending on the flap position and whether or not the CWT is feeding.

Hence 'on' (buttons pushed in) is not really 'on' as far as crossfeeds 2 and 3 are concerned -- rather it is, really, an 'automatic' position.

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I get the FUEL IMBALANCE >FUEL TANK/ENGINE warning, seemingly when I have taken off on a short leg with low % fuel on board.  The message appeared after about 1 hour flying.

In this flight I took off with about 30% fuel on a short 2.5 hour leg.  Yet, as can be seen in the screen shot, the fuel appears to be perfectly balanced.

https://www.dropbox.com/s/6mlsjzg3lchl4fv/FuelWarning.jpg?dl=0

I do not seem to get this problem when on long haul flights, departing with nearly full tanks.

Any suggestions?

 

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8 minutes ago, ozzieblr said:

Any suggestions?

Yes - manage the fuel correctly! 

FUEL TANK>ENG appears when the level in main 2 or 3 is below 1 or 4. This is the case in your screenshot.

Likewise, I forget the threshold for an IMBALANCE message but it is almost certainly referring to the 3.3 tonnes difference between the outer and inner wing tanks.

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7 minutes ago, ozzieblr said:

I get the FUEL IMBALANCE >FUEL TANK/ENGINE warning, seemingly when I have taken off on a short leg with low % fuel on board.  The message appeared after about 1 hour flying.

In this flight I took off with about 30% fuel on a short 2.5 hour leg.  Yet, as can be seen in the screen shot, the fuel appears to be perfectly balanced.

https://www.dropbox.com/s/6mlsjzg3lchl4fv/FuelWarning.jpg?dl=0

I do not seem to get this problem when on long haul flights, departing with nearly full tanks.

Any suggestions?

 

It's not balanced. There are 3,300 pounds more fuel in tanks 1 and 4 than there in tanks 2 and 3. A ""balanced" state and exists when the contents of all four wing tanks are identical. It's OK to have more fuel in the inboard tanks than the outboard, but not the other way around.

 

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Thanks for your info guys ... I used the standard PMDG fuel loading in the FS ACTIONS / FUEL menu, and when loaded, the fuel is balanced as you suggested.  I guess I need to learn the fuel management system better, as it is quite different from the craft I have been flying!

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If you have less than about 54 tonnes of fuel on board at the start of the flight, the fuel levels in each tank will be equal and you will therefore need to go tank to engine immediately. 

The usual method is to turn ALL fuel pumps and crossfeeds ON at the appropriate moment during the before start procedure and wait to see whether FUEL TANK> ENG is displayed (you may need to clear off the other EICAS messages first).

If not, carry on. If it is displayed, you will need to go tank to engine immediately, ie turn off the OVRD pumps in tanks 2 and 3 and close crossfeeds 1 and 4. This will ensure that fuel is burnt evenly from all four tanks during the flight. 

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