Hydraulics Flashcards
How are the hydraulic reservoirs pressurized?
By bleed air
Why are the hydraulic reservoirs pressurized?
To prevent cavitation
What is the normal bleed air source for reservoir pressurization?
Engine 1 bleed air
If bleed air pressure gets low for hydraulic reservoir pressure, what will happen?
Bleed air will be taken from the cross bleed duct
What are the hydraulic reservoirs monitored for?
Low level
Low pressure
Overheat
How is the green system usually pressurized?
By engine driven 1 pump
How is the yellow system usually pressurized?
By the engine driven pump 2.
How is the blue system usually pressurized?
By an electric pump
Which electrical system drives the blue electric pump?
AC1
Which pumps may pressurize the yellow system?
Engine driven 2 pump
Electric pump
Hand pump
PTU
Which electric systems drive the Y electric pump?
AC2 and external power
What pressure do the engine driven pumps and electric pumps supply?
3000 PSI
What pressure does the PTU supply?
2500 PSI
When does the PTU activate?
Automatically when differential pressure between the two systems is greater than 500 PSI.
What does the PTU during the second engine start sequence?
A self test
What is the purpose of the priority valve?
To cut off heavy users (flaps, slats, gears, emergency generator) if system pressure gets too low to operate flight controls
What hydraulic system is used for normal braking?
Green
What hydraulic system is used for alternate braking?
Yellow
When does the RAT deploy automatically?
Loss of AC BUS 1 and 2
Where/ when can the RAT be stowed?
On the ground
What is the function of the hydraulic leak measurement valves and how are they operated?
Measure the leakage in each circuit and are closed by operation of the push buttons on the maintenance panel.
How many hydraulic systems?
3; G B Y
What is the operating pressure of the hydraulic systems?
3000psi
What are the possible pressure sources for the hydraulic systems?
Engine Driven Pumps
Electric Pumps
Ram Air Turbine (RAT)
Power Transfer Unit (PTU)
How is the system pressurized?
By bleed air from Engine 1 or through the cross bleed duct.
What powers the Green System?
Engine 1 hydraulic pump
What does the Power Transfer Unit (PTU) do?
Compares the Yellow and Green systems and pressurizes the lower with the higher if the differential is >500psi.
What backup system does the yellow system have that the green does not?
A backup electric pump and hand pump.
What does the yellow system power?
2 Thrust Reverser
Brakes
Cargo doors
How is the BLUE system powered?
Electric pump ONLY
PTU can not pressurize
There are no engine pumps
RAT
During engine failure or fire, the hydraulic valve closes on the ECAM. What is unique about the Yellow and Green systems when the valve is closed?
Although not depicted, the electric (yellow) or PTU can still pressurize the system without the engine operating.
When is the PTU monitored and what does an amber indication mean?
The PTU is only tested during second engine startup. It is not monitored at any other time.
The amber PTU line on the ECAM means that the PTU has been selected OFF.
What happens when the cargo doors are operated with the engines off?
The yellow electric pump engages when the cargo door is operated.
When will the RAT deploy?
When power is lost to both AC BUS 1 & 2.
When is the hydraulic pressure displayed in amber?
<1450psi
Beside a pump failure, why else would you see a FAULT light on the hyd system?
Reservoir overheat
Reservoir low air pressure
Low Fluid Level
Why would you manually deploy the RAT?
To pressurize the system without activating the emergency generator.
Only required if electric pump is lost and one of the other hyd systems has also failed.
Name the 3 ways the RAT will be deployed?
Auto with loss of AC BUS 1&2
RAT MAN ON pb (no emer gen)
MAN ON on EMER ELEC PWR1
What does it mean when you have all FAULT lights on during pre-flight?
The pneumatic reservoir pressure has bled overnight. APU bleed air will re-pressurize and extinguish the FAULTs
When is the PTU inhibited?
Split Engine Master Switches
+
Nosewheel disconnected or Parking brake ON
+
On the ground
OR
40 seconds after cargo door operation
Why should you delay second engine start 1 minute after cargo door ops?
The PTU is inhibited 40 seconds after cargo door ops to prevent inadvertent pressurizing the green side. When inhibited, the PTU will fail its self-test after 2nd engine start.
What are the 3 types of reservoir problems?
Low Fluid Level
Low Air Pressure
Overheat
