737 center tank fuel pumps

[JP4]

Hi all,
On the NG there is an otion which turns the fuel pump automatically off a while after the fuel low pressure light came on. Does anybody here knows how much time after the light came on?
Thanks for your help
JP

[PA28pilot]

Hi JP4

As you say, this does not apply to all NGs, but where the auto-shutoff feature is fitted it is after 15 seconds of continuous low pressure.

Regards,
PA28pilot

[HAWK21M]

Any details on this Autoshutoff feature.Is it a mod.
regds
MEL

[JP4]

Thanks for that quick answer!

[FCS Explorer]

whole issue came up after TWA800 and other
center tank fuel vapor + fuel pump wire arcing = kaboom incidents.

[Flight Detent]

Guys,
This is a production line update, starting at Line Number 1494, with deliveries starting May, 2004.

This, and other associated mods, were available for post-production retro-fit via Boeing Service Bulletin 737-28A1206, dated 11 January 2006.

Cheers...FD...:)

[Mach E Avelli]

And if you don't have the mod, or don't know for sure if the wiring shielding etc has been done, play safe and switch off BOTH centre tank pumps at the first indication of low pressure. Some guys try to suck every last drop out. If you need the fuel that bad, you are already in trouble.

[hoover1]

i am sure that the book says you can run the pumps for 5 min after the low pressure light comes on. nobody does though.

[Old Fella]

My thoughts are that as soon as it is obvious that the pumps have begun to cavitate, if there is not an AUTO-OFF function, turn them OFF. The pumps depend on the fuel for cooling and lubrication and nothing is gained by running them when the fuel is so low as to be unable to be picked up sufficiently to maintain constant pressure. BTW, it is not just the centre wing pumps which should not be run without fuel.

[Denti]

Isn't the kaboom issue somewhat fixed with the nitrogen generation system that is fixed for the centertank since the second half of 2007? At least ours have it as standard since then.

[FCS Explorer]

the nitro gen is coming slowly and if installed it's deact.
we rely on opening crossfeed at 2,000pds + switching one ctr pump off.
then you get master caution as soon as the other starts blinkin low press

[HAWK21M]

Even on grd Fuel tx ops.The procedure is if One LP lt of the Ctr tank boost pump illuminates its shut off,the second can run until its confirmed that no fuel is being transferred by qty indicators & can be shut off.
Although personally I feel thats running the pump dry.
regds
MEL.

[AeroTech]

Hi,

Here a quote from this link:Fuel (http://www.b737.org.uk/fuel.htm)

Leaving a fuel pump on with a low pressure light illuminated is not only an explosion risk (see Thai and Philippine write offs) but also if a pump is left running dry for over approx 10 minutes it will lose all the fuel required for priming which will render it inoperative even when the tank is refuelled. If you switch on the centre tank pumps and the LP lights remain illuminated for more than 19 seconds then this is probably what has happened. The pumps should be switched off and considered inop until they can be re-primed.

[Lesmana]

Thanks bro ...

[GlueBall]

No center tank fuel pump should be inside the center tank in any airplane! The failsafe location is to mount the center tank pump(s) inside an adjacent main tank. A la DC-8, etc . . .

I'm a Boeing driver and for the life of me I can't comprehend why, after so many center tank explosions, uncle Boeing still keeps mounting center tank pumps inside the center tank. It's engineering stupidity. :{