737NG / A320 Fuel pumps
 

Hey there,
may anyone here please tell me a little about how you use fuel pumps in normal operation @ either 737NG or A320? Have tried several sites containing specs on both A/C...

Do you switch all pumps of during cruise?

Do you have a concrete link?

Normal Ops - Turn 'em on, leave 'em on!

Pure tech... what happens if you switch all of them off?

737: Suction feed from main tanks, however above FL300, thrust loss or engine stall may occur. No suction feed from centre tank, and crossfeed would (for obvious reasons) not be available.

No idea 'bout the bus - prolly computer-generated voice: "I'm sorry - I cannot let you do that, Dave...this conversation serves no further purpose" :D

Empty

'Bus - suction valves close to allow gravity feed to engines.

No spooky voice i'm afraid:D

On the 737 - turn CTR pumps OFF upon low fuel pressure indication (tank nearing empty) - scavange pickups will get the remaining fuel.

The ever-so-thoughtful A320 ;) - I believe the CTR tank pumps have an AUTO-OFF logic when the tank levels are low (5 minute delay ?)

vapilot2004,

On the CL, the scavenege jet pump will only run for 20 min. - but it requres the wing tank pumps to be on in the first place, so if all pumps off - no scavenge pump.

On the NG, the pump operates for the remainder of the flight - but still requres No. 1 tank fwd pump to be operating. Again, it's only a jet pump, so needs pressure from somewhere ;)

Empty

Thanks Empty, for clarification on that :)

I hadn't considered the original poster's query as it would be applied to an (unusual) all pumps off sit.

Anyone wish to confirm that the A320's thoughtful & preprogrammed behavior re: the CTR tanks - Auto-off after 5 min when predetermined low level is reached ?

.....confirmed.