hydraulic system Flashcards
how many hydraulic systems are on the airplane?
3 independent systems
hyd 1, 2 and 3
what systems use hydraulic power
flight controls,
spoilers,
landing gear,
nose wheel steering
wheel brakes
thrust reversers
can hydraulic fluid be transferred between each system
no
how many hydraulic pumps are on the airplane?
7 (if you include PTU)
PTU
engine 1 driven pump
engine 1 electric pump
engine 2 driven pump
engine 2 electric pump
electric pump 3A and 3B
what are the basic components of teh hydraulic system
reservoir
pumps
accumulator
what is the purpose of the accumulator?
helps to maintain constant pressure by covering transient demands
helps to avoid pump cavitations
what are some important items controlled by the HYD 2 system
Landing gear
nose wheel steering
inboard brakes
when will ACMP 1 or 2 automatically activate?
ground:
flaps > 0 and
TL set to T/O or
ground speed > 50 kts
in flight:
engine failure or EDP failure
Flaps > 0
what is the PTU
power transfer unit
mechanical pump that uses HYD 1 power to provide HYD 2 pressure
what is the primary purpose of the PTU
to allow landing gear retraction and extension in the event of an engine 2 or EDP 2 failure
when will the PTU automatically activate?
during takeoff and landing with flaps > 0 if
engine 2 fails or
EDP 2 fails
how is single engine taxi possible if nose wheel steering is on HYD 2
releasing the parking brake activates ACMP 2
what is the primary purpose of HYD 3 system
back up for the flight controls
why does HYD 3A pump have an ON and HYD ACMP 3B have auto?
3A is always on - primary, no automation
HYD 3B - back up and automatically activates if ACMP 3A fails
what, if any HYD ACMP will function if the RAT is the only power source?
HYD ACMP 3A only
