Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

B777 C1 and C2 demand pumps

Tech Log The very best in practical technical discussion on the web

B777 C1 and C2 demand pumps

Old 19th Nov 2012, 19:02
  #1 (permalink)  
Thread Starter
 
Join Date: Mar 2007
Location: Sandpit
Posts: 411
B777 C1 and C2 demand pumps

The manual states that the C1 and C2 demand pumps cannot run together if turned on.

The question is can they run together if they are in auto and system load is high or is it still only 1 at a time?
felixthecat is offline  
Old 19th Nov 2012, 20:23
  #2 (permalink)  
 
Join Date: Apr 2004
Location: wales
Posts: 444
The clue is in the title 'demand' . Wont come on together on selection as the 'demand' isnt there. in flight they will operate when required.
bvcu is offline  
Old 20th Nov 2012, 09:04
  #3 (permalink)  
 
Join Date: Dec 2006
Location: Established on the LOC
Posts: 18
They can operate together in AUTO for take-off. (777 CBT) (Gear retraction, flight control demand, etc.) During landing only one will operate in AUTO. Certain MEL items reflect this when it states that APU has to be running with certain bleed problems to supply bleed air for gear retraction after a go-around.
CharterJake is offline  
Old 20th Nov 2012, 12:34
  #4 (permalink)  
Thread Starter
 
Join Date: Mar 2007
Location: Sandpit
Posts: 411
Thanks for the info Charter Jake

BVCU it's not really in the title since they are demand pumps when in Auto.... When selected to ON then your telling them to come on despite demand.... And as manual says they can't run together if placed in On position.
felixthecat is offline  
Old 21st Nov 2012, 14:12
  #5 (permalink)  

Usual disclaimers apply!
 
Join Date: Nov 1999
Location: EGGW
Posts: 833
Snoop

The only time they will both run is:
Take-off (a/c in ground mode, take-off flaps selected AND ground speed > 80knots).
Undercarriage retraction.
Autoslat demand.
The reason for them both to run is to ensure enough hyd. press. and flow for the rudder (TAC) in the event of an engine failure.
Both ADP's go off after 10secs. in the air.
gas path is offline  
Old 23rd Nov 2012, 11:51
  #6 (permalink)  
 
Join Date: Dec 2006
Location: Established on the LOC
Posts: 18
I didn't have an answer nearly as accurate as gas path's but, I think he is spot on. The CBT that I have is quite a few years old and outdated as such. Looked again in the MEL but didn't find more info. I wish that Boeing would give us a bit more information but if we don't need to know the we don't need to know...
CharterJake is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.