HYDRAULICS Flashcards
(27 cards)
Nominal pressure
3000psi
Systems supplied by HYD SYS
Primary flight controls:
Ailerons
Elevators
Rudder
Secondary flight controls
Flaps/slats
Multifunction spoilers (MFS)
Ground spoilers
Thrust reversers
Landing gear
Nose-wheel steering
Ram Air Turbine (RAT) stow actuator
Power Transfer Unit (PTU)
Backup for Hydraulic system 1
AC Motor Pump (ACMP 2B)
Backup for Hydraulic system 2
How are the reservoirs pressurized?
The high-pressure fluid return acts on a piston to create a positive in the low-pressure section of the reservoir. The positive pressure pushes the hydraulic fluid to the EDP through a Shutoff Valve (SOV) to prevent pump cavitation and to ensure supply during negative g situations.
What does the accumulator do?
Nitrogen pressurized to supply pressure to the reservoir after the pump stops.
Power Transfer Unit (PTU)
Backup for Hydraulic System 1 if EDP 1A fails or when high flow is required
Which system pressure is used by the PTU?
Hydraulic System 2 fluid pressure
AC Motor Pump (ACMP 2B)
ACMP 2B is the backup for HYD SYS 2 if there is a failure of EDP 2A or when high flow is required.
Which BUS powers the ACMP 2B?
AC BUS 1
How is the hydraulic fluid cooled for HYD SYS 1 & 2?
Fuel/hydraulic heat exchanger
HYD SYS 1 & 2 SHUTOFF Valves
Powered by DC EMER BUS (28VDC)
Closes when
Engine fire extinguishing system is armed
Hydraulic fluid over temperature (Closes automatically when the hydraulic fluid temperature exceeds 125*C)
Manual selection by flight crew
Hydraulic system 1 priority valve
If system pressure drops below 1700psi, the priority valve isolates the landing gear control valve to maintain pressure for flight controls and L thrust reverser.
Landing gear can be extended using ALTN GEAR switch.
Hydraulic system 2 priority valve
When system pressure below 1700psi, the HYD SYS 2 PV isolates the PTU to maintain pressure for the flight controls and right thrust reverser.
How is HYD SYS 3 cooled?
Cooled by ventilation in the aft equipment bay
HYD SYS 3 backup pump
ACMP 3B 115VAC, powered by AC BUS 2.
HYD SYS 3 PV
Isolates the flaps and slats POWER DRIVE UNITS (PDUs) to maintain pressure for the flight controls.
How may accumulators in HYD SYS 3?
2 accumulators. Maintains pressure during RAT deployment and dampens pressure transients during rapid movement of hydraulic components.
What is the backup for HYD SYS 3?
RAT. Will deploy automatically is there is a total loss of AC power in flight. Can also be manually deployed.
Pressure supplied by RAT?
2850psi. Supplies pressure to the primary flight controls.
Hydraulic panel-PTU
OFF- The PTU does not operate
ON - PTU operates and supplies pressure to SYS 1 if:
SYS 2 is pressurized and
SYS 1 has sufficient fluid (more than 5%)
AUTO- no over temperature (less than107*C), SYS 2 is pressurized and SYS 1 sufficient fluid (more than 5%), the PTU will operate automatically when:
T/O thrust is applied
Inflight and slats/flaps deployed
EDP 1A failed in flight
Single engine taxi (right engine) when park brake is OFF
Note: when the parking brake is cycled, the PTU and ACMP 2B will operate for 6 minutes
Hydraulic panel- ACMP 2B switch
ON- operates if AC power is available and fluid is more than 5%
AUTO- no over temperature, AC power is available and sufficient fluid, the ACMP 2B will operate automatically when:
T/O thrust is applied
Inflight slats/flaps are deployed
EDP 2A has failed
Right engine failure in flight
PTU has been selected ON
Park brake is set to OFF-single engine taxi
EDP 1A fails or left engine fails
