Hydraulics System Flashcards
Which pumps are engine driven?
primary and secondary pumps
What is the aux pump driven by?
AC motor driven
estimate of normal hydraulic reservoir quantities are-
7, 11, 7, 7
What do the hydraulic systems normally operate at?
4000 psi
If the primary pump falls to 3400 psi, what happens?
the HSC turns on the secondary pump
it will also turn on the pump pressure “Low” light at this psi
What happens when the primary pump pressure comes back to 3850 psi after it was kicked on due to low primary pump pressure?
the secondary pump is automatically depressurized by the HSC
What pressure does the aux pump put out?
3850 psi
When checking the transfer pump during engine start, what should the #3 system pressure show?
at least 3400 psi (or 3000 psi if #2 is ONLY driven by the aux pump)
Why don’t we turn off the aux pump with an engine shut off?
to continue to pressurize the respective hydraulic system
primary system that powers gear
system 3
primary system that powers cargo door and ramp
system 2
primary system that powers brakes
system 2
primary system that powers flaps/trim
systems 1 & 4
primary system that powers slats
systems 2 & 3
Primary purpose of the XFER pump?
to assist in landing gear retraction if the #3 engine fails or assist in cargo door/ramp closing if the #2 engine fails
