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757/777 Fuel Tank Usage

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Hello, all -This is not a topic I've seen discussed before: In older heavy aircraft like the B-29 and B-36, it was SOP to consume fuel from the inboard fuel tanks first. This procedure acted to relieve the bending moment on the wing main spar by distributing the remaining load away from mid-span,.I've noticed that fuel draws from all three tanks on the 757 and 777. Even with a maximum fuel load on the 777, some fuel remains in the wing tanks through a long flight. However, flying the 757 from PANC (Anchorage, AK) to KLAS (Las Vegas, NV), the wing tanks were reading zero before I landed.Question: Do the newer aircraft in the real world not follow the old inboard-out fuel tank usage protocol, is this a Fly!/FlyII program limitation, or what? If I want to drain the center tank first, I suppose I could kill the wing tank boost pumps, but is this actually done? (Old rule: nenver turn off a system you will need later in the flight; Murphy says it may not come on again!)Hope you guys who actually drive these birds can enlighten me here.Regards -- Dave Reed

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Dave,Every Modern A/C I have worked (A320, B757, B767, B777) still burned down the center tank first to keep the fuel in the wings as long as possible. I honestly haven't taken any flights with the PMDG 757 that required center tank fuel so I haven't noticed whether or not the center burns down to zero before the wings start to drop. The 757 Fuel System should be designed so that the Center Tank Bost Pumps (overide pumps) supply more pressure than the Wing tank pumps, forcing Center Tank Fuel to the engines until the tank is empty before allowing fuel to be pumped out of the Center. This also allows an immediate backup in case a pump fails at a bad time. I have a feeling this may be a FLY II limitation as I assume it is modeling the Center tank as an AUX tank but only a guess.Anyone else observed it on the PMDG 757?Paul:-cool

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Paul, Dave,I've done several flights with fuel in the center tank. You have to work the load management manually, since the fuel is drawn from all the tanks with running pumps. I'm not sure, but I think it's mentioned in the manual somewhere...I know I've read it.

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