B777 C1 and C2 demand pumps
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Joined: Mar 2007
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From: Up North….
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?
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?
Joined: Dec 2006
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From: Established on the LOC
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.
Thread Starter
Joined: Mar 2007
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From: Up North….
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.
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.
Usual disclaimers apply!
Joined: Nov 1999
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From: EGGW
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.
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.
Joined: Dec 2006
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From: Established on the LOC
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 The CBT that I have is quite a few years old and outdated as such.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...
