Hydraulics Flashcards
What are the three hydraulic systems?
Green, Blue and Yellow
Which hydraulic systems have fire shut-off valves?
Green and Yellow
Can fluid be transferred between systems?
No
What is the normal system operating pressure?
3000 psi (+/-200)
What is the RAT operating pressure?
2500 psi
Which systems have electric hydraulic pumps?
Blue and Yellow systems
What is the significance of an Engine Hydraulic pump FAULT light?
- Reservoir low qty
- Reservoir overheat
- Reservoir low air pressure
- Low pump pressure
When is the FAULT light inhibited on the Engine Hydraulic pump?
On the ground with the engine shut down
Will switching pump OFF extinguish the FAULT light?
Yes, except reservoir overheat which will remain as long as condition exists.
When does the blue electric pump operate?
- In flight with AC power available
- On ground with AC power available and with one engine running
Which additional fault will trigger FAULT light on the blue system electric pump?
Pump overheat
When does the PTU operate in the air?
When the pressure difference between green and yellow systems >500 psi
Which system is powered by the PTU?
PTU is bidirectional, powers both green and yellow from the opposite system
Which condition will generate a PTU FAULT light?
Green or yellow system:
- Reservoir low quantity
- Reservoir overheat
- Reservoir low air pressure
When is the PTU inhibited?
- During 1st engine start
- When yellow electric pump is used for cargo operations
When is the RAT deployed?
- Loss of AC bus 1 and 2 in flight
- Airspeed >100kts
How many accumulators are installed?
- One per system
What is the purpose of the priority valves?
Preserves hydraulic power for flight controls in case of low system pressure
Which hydraulic system powers the normal brakes?
Green
Which hydraulic system powers the alternate brakes?
Yellow
Which hydraulic system powers the landing gear?
Green
Which hydraulic system powers the Nosewheel Steering?
Yellow
Which hydraulic system powers the slats?
Green and blue
Which hydraulic system powers the flaps?
Green and yellow
How are the reservoirs pressurized?
Using bleed air from engine 1 or cross bleed duct
When does the PTU operate on the ground?
- Green/Yellow diff pressure >500psi, and
- Both engine master switches ON or OFF, or
- Parking brake released
