Hydraulics Flashcards
How many hydraulic systems are installed?
Three independent systems with an A (primary) pump and a B (backup pump). Each has a pressurised reservoirs and a nitrogen charged accumulator.
How are the hydraulic pumps driven?
The main pumps on system 1 and 2 are engine driven. The main pump on system 3 and the backup pumps on all systems are AC driven.
What is the minimum hydraulic quantity required for dispatch?
45% - 85%.
What is the maximum hydraulic fluid temperature?
96ºC.
How are the engine hydraulic pumps shut off?
The hydraulic shutoff valve guarded switches on the overhead panel.
Depressing the fire push switch light.
When the backup hydraulic pumps are set to auto and AC power is available, when do they come on?
When flaps are out of zero.
What are the AC power sources for the AC hydraulic pumps?
1B - AC BUS 2.
2B - AC BUS 1.
How is hydraulic fluid in system 1 and 2 cooled?
RAM air through a heat exchanger in flight, and by an electric fan on the ground if the temperature is above 160ºF and stops when it cools to 140ºF.
Which system services the largest demand for hydraulic power?
System 3.
Which systems does hydraulic system 3 power?
Rudder, elevator and ailerons. IB ground spoilers. Landing gear. Nose wheel steering. IB brakes.
When will an amber hydraulic low pressure EICAS message appear?
When the system pressure falls to 1800 psi.
What is the normal hydraulic system pressure?
3000 psi.
Which hydraulic system provides power to the brakes?
System 3 - inboard brakes.
System 2 - outboard brakes.
Can hydraulic system 2 raise the landing gear?
No, it can only release the nose gear uplock and assist lowering the mains.
