Fuel Logic is it correct??!!!

[FOD 23]

BrianOK - I assumed that readers would realise that we were talking rw, especially as I have never seen any suggestion that PSS models failure modes in their aircraft.Also, if the system was deliberately limited to normal 2 engine operation = fair enough. The only point was that this can lead to some anomalies and questions if you look more deeply into the system and do not realise the limitations in the original spec.RegardsJohn

[Guest NormanB]

John,Whilst my question was of course aimed at our model I certainly appreciate how these can occur in real life. I guess if FS modelled fuel leaks then yes, we would have accounted for that too.

[FOD 23]

NormanPoint taken. I appreciate that MS did no failure modelling in the default aircraft. But this thread has raised one issue - I will message you separately on this.RegardsJohn

[Guest reyramon]

i have to agree...i've this problem when the left tank will drain/use more fuel even when the apu is off. to balance i've turned on the crossfeed and turn the left fuel pumps..and it will use more of the right fuel tanks...but still use some from the left fuel tanks. how is that possible if i've shut the left pumps off and only using fuel from the right tanks?

[Guest dynamania]

Gooday everyone, SheahanAfter ive purchased the the T777-LR/-ER, i played around with it alot, although i haven't master visual approaches with it yet.Okay regarding your issue here's what happened to me on my latest yet shortest flight from Sydney to Auckland... 2 subsequent warnings indicating low pressure in left then right fuel tanks, although i had enough fuel remaining in the center tank but the engines failed and refused to start again.. with the constant warning beeps... untill i managed somewhat i dont know how to start the engines again... after all... i just forgot to switch the center tank pumps ON at the begginning of flight :)First off: if pilots sleep, reliefe pilots are up and vice-versa.You shouldnt use Xfeed in normal conditions... here you have to turn Center Tanks On... when they are emptied, you must turn them off. The center tank pumps override the main tank pumps anyway, so it is used first. You can Refere to the panel manual, see the Fuel system section.Best Regards,and this is a Super Sim PSS guys!Goin' Mad"Dynamania"

[Guest airmann]

Thanks for the replies. I used the default Flight Sim fuel loader to get the right ammount of fuel on board. Could this be the porblem? If so, then I do apologize for my remarks, but I am always using this system as I use the FS passengers fuel loader and the Flight setup page to load fuel. And one more thing, I have done tests with and without corsfeeds, and it does not make a difference, both engines switch off when there is plenty of fuel in the right tank, but none in the left. And let me make an important point here, people keep asking why I would let one tank run down to Zero, Let me begin by saying I am no amature when it comes to flying the new highly realistic PSS/PMDG aircraft. I always use fuel planners, and make sure I have MORE thank enough fuel. BUT THE LEFT TANK IS USED UP FASTER THAN THE RIGHT. !!!!!If i start with say 50T on either side the way that the T7 uses fuel that after a while there will be 20T in the left and 40 in the right, and this is why I end up with 0 in the left and more than that in the right, Crossfeeds, are OFF. And in addition to this wierd consumption pattern the right engine switches off when the left tank is drained???I don't think I made this point in my earlier post; The left tank drains faster than the right. I will continue to do more tests to see if the problem lies in the fact that I was using the Default FS9 fuel loader to board fuel. Its the only thing I can think of which could be the problem, I know PMDG ask that users do not use the FS9 fuel loader, and use their Payload editor instead. Thanks, Sheahan

[Guest NormanB]

Sheahan,I always load the fuel using the fuel utilities provided. The only time I have seen the left tank deplete more than the right is when I have left the APU running, and even then its only a little, certainly not to the extent you seem to be seeing.

[FOD 23]

Hi again Sheahan,I think that we have two totally separate issues here. Firstly the problem of tanks using fuel at a "normal" rate, even when the relevant engine etc is shut down, seems to be a characteristic of this model. Whether it is a genuine bug or whether it is just that the crossfeed performance and single engine performance of the fuel system were not originally modelled in detail I do not know.As to your initial problem, as with Norman, I have always used the PSS fuel loading gizmo. However, I have now tried to reproduce your fuel problem over several flights. On the last one, I loaded the 777 in the "create a flight" screen - as I always do - but I then loaded 50% fuel in left and right and zero in the center. I then flew 3 hours with crossfeed closed and 3+ hours with crossfeed open; in neither case was there any noticeable discrepancy in the amount of fuel used. The system operated exactly as if I had loaded the fuel using the PSS utility.Perhaps you could look at what happens if you use the PSS fuel loader - if the problems still remains: a new installation?, rebuild the FS9.cfg?. In fact all the usual culprits which I am sure that you know better than I do.Let us know how you get on.RegardsJohn Rooum