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Ralgh

Center tank fuel pump lights

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I have noticed that the center pump lights are illuminated "OFF" when the pumps are switched off. Every plane I have flown with center tank pumps (F100, 737, jumpseat 757/767)the center tank pump lights turn off when the switches are off because that is not an abnormal position (this preserves the dark cockpit theory). They only illuminate when the switch is on and there is low pressure. I have noticed that the pumps show off on the ECAM when there is no fuel in the center tank with the switches on. Is this normal in the real Airbus, to always turn the pumps on even if there is no fuel in the center tank or is this just the way PSS modeled it? All modern airliners I am aware of usually have it set up so that when the switches are in the in flight position all the lights are out (dark cockpit).

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Airbus Industrie instructions state that the centre pumps must be OFF if there is no fuel in the centre tanks. Indeed some airlines take this further and don't allow takeoff with the centre tank pumps on whether or not there is fuel in the centre tanks. So the PSS is correct with the modelling between the On, Off and Fault states. In the rw version the Fault light illuminates when the centre tank has more than 55 pounds of fuel and the left or right wing tank has less than 11000 pounds, but to be honest I've never checked whther these figures are the same in the PSS. I'll have a look.Rob Elliott, EGPE InvernessPSS Airbus Support andAirbus Fleet Training Captain, British Airways Virtual airbus@speedbirdonline.co.ukhttp://www.speedbirdonline.co.uk/airbus.htmlhttp://www.bavirtual.co.uk

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Hi,Real World:Yep CTR tank pump switches are always selected on per normal procedure.If there is no fuel the logic will keep them from running dry.Cheers, Sjaako

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If there is no fuel they cannot run dry: they already are! The CTR tanks are not always selected on in normal procedures if there is no fuel in the centre tanks. If there is no fuel in the those tanks Airbus Industrie SOPs are that the pumps are switch off.

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Hi,Well I don't know which FCOM's you use but the ones from Toulouse I have here state they are ON.After flying the Nintendo for 2000 hours I have never switched them OFF unless there is a problem with the fuel pump logic.Airbus only has lights ON when there is a non normal condition so flying around with OFF lts would not be normal procedure.If you switch them off the aeroplane will tell you that not all the fuel is useable, which requires a checklist.Dry running means the pumps are running without fuel. Danger of vapours and tank combustion.Cheers Sjaako

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It's on an Airbus notification I have here somewhere and is also in the GB Airways FCOM. The latter states that if no fuel in the centre tanks then the centre pumps must be off for takeoff. However, if there is any fuel (and many GB Airways flights do need fuel in the centre as well as the wing tanks) then the pumps can be on. It is apparently to do with electrical arcing and was the cause of a (Boeing) problem a few years back.Edit: the quote is "If operating in Manual mode the crew must ensure that the center tank pumps are off when the wing tanks are completely full or when the center tank is empty."Edit 2: Ah ha, I've just noticed that little word Manual. In Auto this would not apply.Edit 3: Fuel tank philosophy was never my strong point :)Rob Elliott, EGPE InvernessPSS Airbus Support andAirbus Fleet Training Captain, British Airways Virtual airbus@speedbirdonline.co.ukhttp://www.speedbirdonline.co.uk/airbus.htmlhttp://www.bavirtual.co.uk

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No worries Rob,Thanks for sorting it out,Cheers guysSjaako

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HiTo add, Center Tank Pump are allways OFF during Take-off (AUTO mode), provided slats are extended, because the position of the slats now controls the operation of the center tank pumps.Edinhttp://www.inet.hr/vegabric

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I talked to my brother tonight. He is a captain with Frontier, and flys the A319. Here's what he had to say.When the switch is dark, it is not necessarily "off", but in the "auto" mode. The center tank supplies fuel first, except on takeoff. Here is the normal timeline...Assuming we have fuel in the center tank, the center tank provides fuel for the first two minutes during pushback and startup. When they turn to taxi, flaps 1 is selected which shuts down the center tanks and goes to the wing tanks. You never want to take off with both engines running off one tank for obvious safety reasons.After takeoff and flaps up, the center tank kicks back in and supplies fuel until empty, running five minutes more before shuting down. The center pumps have a higher pressure than the wing pumps, so fuel is supplied from the center tank until exhausted. I believe there is an ECAM message while the center tank is supplying fuel.They (AirBus) has now recommended shutting the pumps off while parked at the gate. Before now, the fuel pump switches remained dark and they didn't have to fool with them since the AirBus is so automatic.LVP (KCVG)

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Oh Yes Centre Tank Pumps Again...........When I Flew the Bus our procedure was to switch off ALL fuel pumps after engine shutdown. As you said the the CTR pumps are depending on the flap position, to be very precise it's the SLAT position that is monitored by the auto logic.Why would you not want to Take off on the centre tank? The 777 is more than happy to use CTR fuel during Takeoff.......... Must be some other reason.CheerioSjaako

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Add the 737, 757, 767 to the planes that feed exclusively from the center tank when they contain fuel.

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Hi.If I remember correctly from my Airbus course, Take-off with Center-tank Pump ON is prohibited, because If center tank fuel for any reason is contaminated (by water for example), then both engines will stop because they are feeded from same tank. So during take off each engine must be feeded by separate fuel tank (LH Wing Tank for ENG#1 and RH Wing Tank for ENG#2). Hope this helpsEdin Hasanovichttp://www.inet.hr/vegabric

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Hi Again,In auto I've always took off with all pumps selected on (Maybe armed if you like that better).Manual you have a point.But still, if the center tank is contaminated, why not the wing tanks? Water tends to spread evenly in the bowser. All Boeings I've flown always allow CTR Feeding.I think there is some advanced Fuel/Oil heat exchanger that requires wing fuel to be used first. Check the FCOM on that.......Cheerio Sjaako

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Hi.I think that for Center Tank Pump not running at Take -off (Auto mode), there is some regulative, which said that at Take-off each engine must be supplied from separate fuel tank (not case when Center tank pumps running).Also, there is allways possibility of Water Drain valves malfunction. About regulative I will check this, because I'm not 100% sure.And yes, some fuel is used to cooldown IDG Oil. Return valve allows the hot fuel to be returned to wing outer-cell. This cooling also works with center-tank fuel, but because all recirculated fuel is returned to wing-tanks, when FULL sensor in Wing Inner-cell is reached, center tank pumps stops automatically. If all tanks are full, after Take-off (slats retracted), first center-tank fuel will be used (Centar Tank pumps have a priority), and outer wing fuel will be used last, because of wing bending moments. Edin

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>I think that for Center Tank Pump not running at Take -off>(Auto mode), there is some regulative, which said that at>Take-off each engine must be supplied from separate fuel tank>(not case when Center tank pumps running).Also, there is>allways possibility of Water Drain valves malfunction. About>regulative I will check this, because I'm not 100% sure.This is true. The FAA and JAA mandates that during takeoff and landing, the fuel tank nearest the respective engine (in the case of the A320, the inner wing cells) are to be used to feed the engines.>If all tanks are full, after Take-off (slats retracted), first>center-tank fuel will be used (Centar Tank pumps have a>priority), and outer wing fuel will be used last, because of>wing bending moments. Center tank priority is accomplished through higher fuel pressure being fed from the center tank, therefore "taking over" the fuel feed from the lower pressure wing tank pumps. Outer wing fuel is used by draining down into the inner cell. Fuel cannot be taken from these outer cells any other way.

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HiOh well no FAA/JAA approval for any of the boeings than.............Cheerio Sjaako

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Well, then for example you did take off with the center tank feeding the engines, how would fuel get to the engine driven fuel pumps if there was a loss of AC power? All the wing and center tank fuel pumps are AC power driven (except for the APU fuel pump in most cases), so in case of a failure, suction and gravity would feed the engines from the wing tanks. This would be highly unlikely in the event the fuel is coming from the center tank.

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Hi All,Well I take off a few times a week with feed from the CTR tank (Boeing) and still here to tell the tale.When you feed from the CTR tank doesn't mean the wing tank is exluded from the feeding lines. Even when the CTR tank is empty or restricted flow will be taken over from the wing under pressure feed or suction feed.CheerioSjaako

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I guess its different depeding on the carrier. I worked for two major carriers (both Airbus and Boeing operators) and takeoff with CTR tank fuel was prohibited.

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