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Guest Devlin

Fuel

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Hi,Another question from a noob to this aircraft,I keep getting a prompt telling me that the fuel in the tank I have chosen is critical,and the centre tank shows nearly empty, but the wing tanks are full,I would have thought that fuel would be drawn from all tanks automatically when required.how do I get to draw from all tanks not just the centre?I have all pumps turned on.

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Hi,(you should really sign your name by the way.. you'll get an ear bashing about forum rules)I don't know what you mean by "chosen fuel tank".. but let me explain to the best of my knowledge how the system works.Firstly, you're not fully in control of the fuel in the tanks, there is in fact a fuel management system with logic that controls flows and distributions to a point. When starting on the tarmac with say 140,000Kg of fuel on board, you'll notice that to set the panel correctly you'll probably need to switch on all the pumps (that is .. CTR L and R... MAIN 1 2 3 and 4 FWD and AFT along with OVRD 1 2 FWD AFT) and open the cross feed valves to the outboard tanks. In this configuration I believe fuel is taken from the centre tank first.. As the tank empties an FMC message will appear on the EICAS alerting you.. CTR L PUMP and R PUMP or something (can't remember the exact message). What this is telling you is that the pressure at those pumps is in fact low and that is a result of the fuel in the centre tank being low. On the overhead panel you'll see PRESS lit on the two centre tank pumps as another annunciation of the low pressure. Turning off the centre tank pumps will remove this message. If you look on the EICAS LOWER you'll notice that there is a small green arrow from CENTRE tank to the first tank on the left of the aircraft (can't remember which one that is).. this is the salvage pump pulling out the last of the fuel from the centre tank and depositing that fuel into the first MAIN tank on the left. This will continue till CENTRE is empty.Now you will continue flying, and eventually at around 50,000Kg of fuel you will reach the TANK to ENGINE condition. This is the point where all 4 main tanks contain a similar amount of fuel. At this point you close the cross feed valves to the OUTBOARD tanks (those switches without covers over them) so each engine has it's own tank supply. The point of this is to ensure an even distribution of weight to enable more stability.When flying the 747-400, you don't choose a tank as such, the system will organise itself automatically. Just before takeoff ensure all fuel pumps for tanks containing fuel are primed and that the cross feed valves to the outboard tanks are open if fuel is over 52,000Kg.. The system will then prompt you to do whatever you need. It's not a case of choosing a tank to burn fuel from.Not sure that helps.. in my tutorial on the speedbirdonline (british airways virtual) website I explain the fuel system in a bit more detail..Hope that helpsCheersCraig

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Craig gave you a lot of good info... but one more item needs to be stressed: You need to read the documentation that came with the airplane. This is not like a MSFS default aircraft that you can load and go... there's a lot to understand especially fuel system.

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To add to what Dan just said. You really have to learn to fly these nice payware aircraft from a systems perspective. They are not "light the fires and kick the tires" aircraft as most all the FS defualt and freeware addons are. Without a fundamental understanding of the aircraft systems you will be hard pressed to get much out of the experience these aircraft provide. The good news is that they are producing much more realistic aircraft. The bad news is that they are producing much more realistic aircraft. Be careful what you ask for. As was said, read the documents...

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Both Dans are right here...There are a lot of new users buying PMDG and the like products that just do not understand what they are doing, and then asking quite elementary questions (no dis-respect intended here but it is the truth).. I remember my first experiences with PS1.3 (a dos based 744 sim).. A friend had this and it took us both quite a lot of reading and trying things out to understand what switches did what etc.. Even then in some flights we had problems.. Now my knowledge is much more extensive and detailed.. and I have very little trouble flying the plane by hand or with the automatics.. and can get it to do whatever I want..If you're having these kinds of troubles now.. I really REALLY recommend that you have a look at the tutorials on the PMDG site FIRST.. and then perhaps attempt one of those on the BAV site here..http://www.speedbirdonline.co.uk/747.htmlI have written a tutorial (although there are mistakes in it) that takes you on a flight from Heathrow to Los Angeles.. It's not just a "push this button" "press this button".. it explains what the buttons do and why you are pressing them with the overall intention you learn WHAT things do and their context of use... Within this there is a lot of detail regarding the fuel system and its operations with illustration.. I suggest you do these.. and that will give you some experience of the avionics and automatics of this plan that I didn't get when starting out.CheersCraig

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The fuel system draws fuel from the Center Tank (and Stab Tank) first because this reduces stresses on the airframe and helps keep the plane in balance (fore-aft).The semi-automatic nature of the fuel system allows the pilots better control over the fuel system (should a fuel system fault develop).Cheers.Q>

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Thanks for your help guys.I will immerse myself into the manuals and the tutorial,Thanks again, trying to run before I can walk,I think.

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>Both Dans are right here...>>>CraigCraig is right there. This aircraft is so wonderful because there are always new things to learn about it. I'd say that 92% of the users (including myself) really do not fully appreciate the level of attention that is built into it. I wonder how many have even tried the different malfunctions that can be triggered!I'd also strongly recommend going through the type rating courses you can download from PMDG. And definitely get the Virgin Atlantic EGLL-KSFO video from ITTV!

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