A320 Hydraulics Flashcards
What are the three hydraulic systems?
Green, blue, and yellow
What major components are operated via hydraulic power?
Flight controls, flaps and slats, landing gear, cargo doors, and the emergency generator
What is the normal hydraulic pressure provided by the engine driven hydraulic pumps?
3000 psi
What components can provide backup hydraulic pressure?
-Electrically driven hydraulic pumps (on the blue and yellow systems)
-A power transfer unit (PTU)
-A ram air turbine (RAT)
-A hand pump
What prevents hydraulic fluid from returning to the engine driven pump during an engine fire?
A hydraulic fire shutoff valve upstream from each engine driven pump
Which hydraulic systems have an associated acccumulator?
All 3, green, blue, and yellow.
What do the accumulators in each system do?
Help maintain a constant pressure during transient demands
What are some items powered by the green hydraulic system?
Landing gear*
Normal brakes*
Engine 1 reverser*
Slats/flaps
Other flight control components
- ONLY powered by the green system
How is the nose wheel steering different for older vs newer A320’s?
It was originally on the green hydraulic system, but newer aircraft have it on the yellow system.
*I need to refer back to our operating manuals to know which aircraft of ours are configured in which way
How is the green system pressurized?
Normal pressure comes from a single engine driven pump powered by engine number 1. Backup pressure can be provided by the PTU.
What are some items powered by the yellow hydraulic system?
Nosewheel steering* 1
Alternate brakes*
Parking brake*
Engine #2 reverser*
Cargo doors*
Flaps
Other flight control components
*ONLY powered by the yellow system
1 On older aircraft the nosewheel steering may be powered by the green system
How can the yellow hydraulic system be pressurized?
-Via a single engine driven pump on engine #2
-Via an electric pump
-Via the PTU
-Via a hand pump, in order to open the cargo doors when the aircraft is unpowered on the ground
What are some items powered by the blue hydraulic system?
-The emergency generator*
-Slats
-Other flight control components
*only powered by the blue system
How can the blue system be pressurized?
-An electric pump
-A ram air turbine
Which systems have a fire shutoff valve?
Green and yellow
How can the fire shutoff valves be closed?
By pressing the ENG 1 FIRE and ENG 2 FIRE push buttons
What does it mean if the 1 or 2 indications on the hydraulic page turn from white to amber?
That the 1 or 2 engines respectively have shut down
If the green or yellow fire shutoff valves are closed, can the systems still be pressurized?
They can by the PTU. The hydraulic fire shutoff valve only keeps hydraulic fluid from flowing to the engine driven pump but not from flowing to the PTU.
What happens when the ENG 1 PUMP or ENG 2 PUMP push buttons on the overhead panel are pressed?
The respective engine driven pump is depressurized, OFF appears in white on the pushbutton, and the pump symbol changes to an amber dash on the hydraulics page.
What does the fault light on the ENG 1 PUMP or ENG 2 PUMP push buttons mean?
It means any of the following:
-Low pump output pressure
-Low reservoir quantity
-Reservoir fluid overheat
-Reservoir low air pressure
Which systems have electric pumps?
Blue and yellow
Will the yellow electric pump come on automatically if yellow system pressure is low?
No
When will the yellow electric pump operate automatically? What is powered when it’s operated automatically?
Prior to engine start, when the cargo door selector is placed in either the open or closed position. When this occurs only the following are powered
-The cargo doors
-The alternate brake system
-The engine two thrust reverser
*the ON light in the yellow ELEC PUMP pushbutton will NOT illuminate when the pump is operated automatically
When does the blue electric pump operate automatically?
If AC power is available:
-On the ground when at least one engine is running
-In flight, it operates continuously even if both engines are shut down
When does the PTU become active?
Whenever the PTU pushbutton is in AUTO (lights out) and a differential pressure of at least 500 PSI is sensed between the yellow and green systems.
What memo appears when the PTU is in operation?
HYD PTU is shown on the memo section of E/WD
Does the PTU transfer fluid between the green and yellow systems?
No, just pressure
Can the PTU output pressure meet all the demands of the respective systems operating requirements?
Yes!
When does the PTU fault light come on?
For either the green or yellow systems:
-Fluid overheat
-Low air pressure
-Low fluid quantity
When is the PTU inhibited?
-When the yellow systems electric pump is running due to cargo door operation
-During engine start, when the ENG MASTER switches are in opposing positions and either the nosewheel steering is disconnected, or the parking brake is on.
When does the PTU perform a self test?
Momentarily during the second engine start
When does the RAT deploy automatically in flight?
If both AC BUS 1 and 2 are unpowered, and airspeed is above 100 knots. The RAT does NOT automatically deploy for a loss of hydraulic pressure.
Where is the RAT located?
Under the fuselage near the left wing root
How does the RAT supply emergency power?
The RAT provides pressure to the blue hydraulic system. The blue hydraulic system then uses hydraulic pressure to run the emergency generator.
What does the RAT MAN ON pushbutton on the hydraulics panel do?
It manually deploys the RAT to provide blue hydraulic pressure but does not cause the emergency generator to come on line.
What does the EMER ELEC PWR MAN ON pushbutton on the EMER ELEC PWR panel do?
It manually deploys the RAT powering BOTH the blue hydraulic system, and the emergency generator.
What message is displayed any time the RAT is extended?
RAT OUT is displayed in the memo section of the E/WD
Once deployed, how can the RAT be stored?
Only by maintenance personnel
Is the status of the hand pump displayed in the cockpit?
No
When is the hand pump used?
Only when the aircraft is unpowered to provide yellow hydraulic pressure to open/close the cargo doors. If the aircraft had electrical power available, i.e. ground power was connected, then the yellow electric pump would come on automatically to open and close the cargo doors.
Can the aircraft be flown with a loss of all hydraulic systems?
No, you must have at least one
What is the normal system hydraulic pressure?
3000 PSI
If the accumulator pressure is low and an external walk around is to be completed, what should you do?
Obtain ground clearance, then turn on the yellow electric pump to pressurize the accumulator
When is the PTU inhibited (version 2)?
-First engine start
-Parking brake is set and only one ENG MASTER switch is ON
-NWS in towing position and parking brake released
-Cargo door operation (PTU is also inhibited for 40 seconds after the end of cargo door operation)
-PTU pushbutton off
If the ECAM actions lead you to turn off the PTU for a reservoir overheat, will the fault light extinguish?
No, not until the overheat subsides
If the FAULT light in the PTU pushbutton is ON, are there any other indications on the hydraulic panel?
Yes, the FAULT light will also be illuminated on the respective ENG PUMP pushbutton
Can the yellow electric pump run the PTU?
Yes
What is the function of the hydraulic priority valves?
It cuts hydraulic power to the slats, flaps, landing gear, and emergency generator if pressure drops below a predetermined value
What normally provides air pressure to the hydraulic reservoirs?
ENG #1 HP bleed air pressures the reservoirs automatically. If the bleed air pressure is too low, the system takes bleed air pressure from the crossbleed duct.
