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ahinterl

MD-11: Fuel tutorial

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I know, there's a statement in the manual that a tutorial for ballast fuel will come, but is there some information source about the fuel system in some more depth than the manual describes in the meantime? I don't know how informative the ballast fuel manual will be...I have the impression that the fuel system is one of the most complex systems in the MD-11, especially together with the shifting CG, and I'd like to get an idea how to manage fuel and CG by hand in manual mode during an entire flight. Let alone the ballast fuel feature, I played a little with it and have not found a pattern what the logics do when entering ballast amounts for different configurations, the pumps transfer here and there immediately even on ground, sometimes manual mode is required and I don't know why...Andreas

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There is not a tutorial (yet). The ballast fuel is used with light loads to manage cg, heavier loads should not require it. Fuel in ballast is considered unusable.

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I know, there's a statement in the manual that a tutorial for ballast fuel will come, but is there some information source about the fuel system in some more depth than the manual describes in the meantime? I don't know how informative the ballast fuel manual will be...I have the impression that the fuel system is one of the most complex systems in the MD-11, especially together with the shifting CG, and I'd like to get an idea how to manage fuel and CG by hand in manual mode during an entire flight. Let alone the ballast fuel feature, I played a little with it and have not found a pattern what the logics do when entering ballast amounts for different configurations, the pumps transfer here and there immediately even on ground, sometimes manual mode is required and I don't know why...Andreas
As Dan said, Ballast fuel is only use to keep CG within limits at very light weight. Personally i used for real only during empty ferry flights (normally 10000 kg on the upr aux tank). You are right, Fuel system is the most complex one on this plane and its operation in manual mode can be challenging if some failure are present. If you have no failures but only the system in manual, all you have to do is to check the cg position. Anyway tail tank is normally emptied by the fuel system controller in manual mode so the cg position moves forward avoiding any risk but increasing fuel burn by about 2%. In case of failures in the system, then it gets really too complicated to be described here.David.

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I just asked because in my quest to understand the MD-11, I started from cold&dark (and I'm still only one step further with engines now running ;-) ) and played with FMC entries and the PMDG loader program. When I change fuel amounts and the values for ballast fuel, it happens in certain situations that immediately after defining the ballast amount, pumps start to transfer fuel to and from tanks in some order, sometimes the system logic tells me I need to switch to manual mode etc.The background is that at the moment, given the informations in the aircraft systems manual, I have no idea what the fuel logic does when entering ballast fuel amounts in the FMC and why it starts pumping fuel around, and what I'm expected to do in manual mode when some pumps become amber in the fuel synoptic...I don't even know where the CG is expected to be during flight phases, all I know that it's more to the aft during cruise...A little more information about the way the whole fuel distribution and logic works would be nice, especially information on ballast fuel and the placement of tanks when viewed from the plane's side... Managing the entire fuel flow by hand only from TO to landing is currently unexplained for me...Andreas

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A little more information about the way the whole fuel distribution and logic works would be nice, especially information on ballast fuel and the placement of tanks when viewed from the plane's side... Managing the entire fuel flow by hand only from TO to landing is currently unexplained for me...
A little information about this can be found here.

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I REAL fuel planning app is needed. I grow tired of hearing about copyrights and other inhibitive factors. Surely there is something we can do.

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Dunno about ballast fuel, I can't work out how to pump fuel into the tail using the panel lol.Out yes, in NO lolSuch is life.John Ellison

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