Center tank fuel pumps

[Guest kame]

Aaron said on "737NG Fuel":>-----------, if you want real-life accuracy then you should monitor your fuel usage and shut off the center tank >pumps when you have 1000lbs in the tank. You should always have at least 1000lbs in the center tank to keep >the pumps submerged.>This is a new regulation to prevent the fuel pumps from overheating and igniting residual fumes in the tank, >which is suspected as the cause of the 747 that blew up over NY a few years back.However, PMDG 737NG's center tank fuel pumps don't work correctly.Although the center tank fuel pumps shut off, the center tank has been emptied first. Sincerely,Kan-ichiro Fushihara

[Guest]

Not quite. It's up to the pilots to shut down the pumps to the center tank before the tank is completely drained. The aircraft isn't programmed to do so automatically (though maybe Boeing has/will have a software upgrade to bring on the warning lights before the tank is empty).

[Guest canyonblue737]

>Not quite. It's up to the pilots to shut down the pumps to>the center tank before the tank is completely drained. >The aircraft isn't programmed to do so automatically (though>maybe Boeing has/will have a software upgrade to bring on the>warning lights before the tank is empty).it's actually far more complicated than you dream...center tank pumps should be OFF for takeoff when center tank quantity is less than 5000. you will have a config warning on the guage but that's ok.you can turn back on center tank pumps during the climb when at 250 knots OR pitched to accelerate to 250 knots.in climb or cruise with center tank fuel below 2000 lbs you must open the crossfeed and turn ONE of the center tank pumps off.in descent with center tank fuel below 3000 lbs you must open the crossfeed and turn ONE of the center tank pumps off.in the air as long as you follow the above rules and turn off both center tank pumps as soon as the one center tank pump you are running runs low pressure (ie. the tank is dry) you are safe. the 1000 lbs rule refered to before is for non-NG aircraft and is only an on the ground rule... you certainly can run center tanks dry in all models of the 737 you just have to follow procedure.

[CF104 0]

Hi Dave,According to this AD 2002-24-51 http://www.airweb.faa.gov/Regulatory_and_G...6E?OpenDocument which covers the 737NG series, there is still a 1000lb limit in cruise for the centre tank with certain fuel pumps installed.Cheers,JohnBoeing 727/737 & Lockheed C-130/L-100 Mechanichttp://www.precisionmanuals.com/images/forum/ng_driver.jpg

[Guest frankathl]

Interesting post, Dave.Are all of the actions to ensure center pumps are submerged(in different flight phases), or are there other reasons, as well?Thanks,Frank

[Guest canyonblue737]

>Hi Dave,>>According to this AD 2002-24-51>http://www.airweb.faa.gov/Regulatory_and_G...6E?OpenDocument> which covers the 737NG series, there is still a 1000lb limit>in cruise for the centre tank with certain fuel pumps>installed.>>Cheers,>>John>>Boeing 727/737 & Lockheed C-130/L-100 Mechanic>>http://www.precisionmanuals.com/images/forum/ng_driver.jpgintresting... this is from the AD:"The center tank fuel pumps must be OFF for takeoff if center tank fuel is less than 5,000 pounds (2,300 kilograms) with the airplane readied for initial taxi.Both center tank fuel pump switches must be selected OFF when center tank fuel quantity reaches approximately 1,000 pounds (500 kilograms) during climb and cruise or 3,000 pounds (1,400 kilograms) during descent and landing. The fuel pumps must be positioned OFF at the first indication of fuel pump low pressure.The CWT fuel quantity indication system must be operative to dispatch with CWT mission fuel.NoteThe CONFIG indicator will annunciate when center tank fuel exceeds 1,600 pounds (800 kilograms) and the center tank fuel pump switches are OFF. Do not accomplish the CONFIG non-normal procedure prior to or during takeoff with less than 5,000 pounds (2,300 kilograms) of center tank fuel or during descent and landing with less than 3,000 pounds (1,400 kilograms) of center tank fuel."the procedure here is similar but not the same as what we use. in low center tank scenarios in flight we open the crossfeed and turn one pump off to create a Master Caution light at the first sign of an empty tank (if we had two pumps on, both would need to indicate low pressure first) and we do not need to shut the pumps down at 1000 lbs.

[Guest]

personally I think it's just to give the button pushers something to do to keep em busy...

[CF104 0]

>the procedure here is similar but not the same as what we use.>in low center tank scenarios in flight we open the crossfeed>and turn one pump off to create a Master Caution light at the>first sign of an empty tank (if we had two pumps on, both>would need to indicate low pressure first) and we do not need>to shut the pumps down at 1000 lbs.Hi Dave,It may be that the company you work for applied for an Alternate Method of Compliance for this AD and that is why your procedures are not exactly the same as the AD. Anyway, the AD is good reading for those that wish the utmost in realism while operating the NG.Cheers,JohnBoeing 727/737 & Lockheed C-130/L-100 Mechanichttp://www.precisionmanuals.com/images/forum/ng_driver.jpg