Jump to content

Archived

This topic is now archived and is closed to further replies.

JD396

AC pumps for the APU

Recommended Posts

If I'm sitting on the ground with the APU running for a while, is it "proper" to run two AC pumps, from both the left and the right tanks? I notice it works just fine to prevent potentially having to deal with a fuel imbalance later. There's no fuel config warnings in the cockpit or anything about it, and nothing I could find in the FCOM tells me NOT to do this, but it doesn't tell me TO do it either. I guess I'm wondering, is that something that ever happens in the RW?


Jack DeMarre

Just an earthbound misfit

 

My Current Flight Sim Setup: She ain't much to look at, but she's got it where it counts.

My New Build: Phase 2 - Project Planning. Working on justifying expense to wife.

Share this post


Link to post
Share on other sites

You can I guess but I don't think it is something normally done as the APU will use it's own DC pump if it needs, a fuel imbalance is something easy to fix later rather than run AC pumps for long periods of time when not needed.


Jay Vorkapic

 

pmdg_trijet.jpg

Share this post


Link to post
Share on other sites
You can I guess but I don't think it is something normally done as the APU will use it's own DC pump if it needs, a fuel imbalance is something easy to fix later rather than run AC pumps for long periods of time when not needed.
Yeah, it doesn't take more than a couple minutes to solve a fuel imbalance, and you have to run it for a good long while to actually get an imbalance big enough to trigger the warning. The FCOM suggests running one of the AC pumps for "extended APU operation" on the ground... kinda vague.

Jack DeMarre

Just an earthbound misfit

 

My Current Flight Sim Setup: She ain't much to look at, but she's got it where it counts.

My New Build: Phase 2 - Project Planning. Working on justifying expense to wife.

Share this post


Link to post
Share on other sites
If I'm sitting on the ground with the APU running for a while, is it "proper" to run two AC pumps, from both the left and the right tanks? I notice it works just fine to prevent potentially having to deal with a fuel imbalance later. There's no fuel config warnings in the cockpit or anything about it, and nothing I could find in the FCOM tells me NOT to do this, but it doesn't tell me TO do it either. I guess I'm wondering, is that something that ever happens in the RW?
RW, use one pump at a time. The planes come from Boeing with an option for a DC pump that will suction feed from the left main tank. To prevent fuel imbalance, use the center tank fuel by switching the left pump on. If you don't have center tank fuel, switch between the main tanks by turning on one of the aft pumps. If you use the right tank, you must also open the cross feed valve.

Matt Cee

Share this post


Link to post
Share on other sites

Correct. IRL I see Main tank #1 aft pump operating for APU 99% of the time. Doesn't seem to be a problem. sig.gif

Share this post


Link to post
Share on other sites

  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
  • Donation Goals

    AVSIM's 2020 Fundraising Goal

    Donate to our annual general fundraising goal. This donation keeps our doors open and providing you service 24 x 7 x 365. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. We reset this goal every new year for the following year's goal.


    42%
    $10,670.00 of $25,000.00 Donate Now
×
×
  • Create New...