Hydraulic System Flashcards
Hydraulic system nominal pressure
176 +- 14bar
Hydraulic system provides power for
NWS
Landing gear
Brakes
Speedbrake
Flaps
Ail servo control
Initial charge of accumulator
59 bar (860psi)
Emergency hydraulic provides power for
Emergency gear extension only
Emergency braking
The Separation Valve is set at a pressure of
108bar
Main hydraulic system components
Reservoir 16,25lt
Accumulator
Engine-driven pump (variable flow)
2 filters
Relief valve
Zero setting selector valve
Emergency hydraulic system components
Separation valve
Emergency accumulator
Zero setting selector valve
How many pressure transducers in the hydraulic system
2, one for the main and one for the emergency
Signals received from hydraulic pressure transducers are sent to
EDAB for showing on the MFD
HYD PRSS comes on when?
In case of low hydraulic pressure in the Emergency System (70bar)
What does happen to hydraulic system when the aircraft becomes airborne?
The solenoid valve closes isolating the 2 systems
What can you expect from hydraulic indications when performing a steep climb?
A pressure drop in the Emergency System because of Nitrogen pressure decreasing because of cooling of the accumulator
What element is used to guarantee pressure from the hydraulic accumulator?
Nitrogen (N)
The solenoid separation valve is operated by
A solenoid that is energized while on the ground (open) from a switch on the left landing gear struct
After an Emergency Gear Extension, when the A/C is back on the ground, what does happen to the hydraulic system?
The isolating valve opens if in the main system there is at least a pressure of 108bar, allowing to all the fluid stored in the accumulator to be directed towards the emergency system for application of emergency braking by using the handle.
In what direction only the separation valve opens?
From main to emergency
Aileron Servo uses a pressure reduced from ___ to ___
From 176bar to 146bar by a pressure reducer
Pressure reducer valve (ail servo) is controlled by what switch?
AIL SERVO switch in each cockpit
AIL SERVO comes on when
Pressure < 61bar
In case of hydraulic pump failure, the accumulator provides power for which systems
Landing gear extension
Wing flaps
Wheel brakes
Ail servo control (temporary use)
NO
NWS
Speedbrake
Hydraulic pressure relief valve opens and closes at which values?
235 bar opens
201 bar closes
Name the 4 hydraulic selectors from left to the right
Gear doors
Landing gear
Speedbrake
Flaps
How is it possible to understand if one of the 2 filters in hydraulic system is clogged?
Red pin pops out
Why in the hydraulic system on ground is used a pin?
To prevent electrical power to reach the selectors and therefore actuate the system
Where the 2 pressure accumulators of hydraulic system are located?
Left fuselage
Where the hydraulic reservoir is located?
Right side of the fuselage
Hydraulic reservoir capacity
16,25lt
What are the names of the 2 filters of hydraulic system
Main filter (filter fluid exiting the pump)
Return filter (filter fluid going back to the reservoir)
Hydraulic filters can filter up to
5microns
What happens to hydraulic system in case of a huge leak on ground to the main system?
The isolating valve closes at 108bar allowing emergency braking action
What could be the first indication of Hydraulic pressure drop in the main system?
AIL SERVO on
Minimum pressure to operate flaps
40bar
Min pressure to operate NWS
70-80 bar
Min press to operate landing gear
110bar
What’s the hyd fluid color?
Red
At what temperature does the hyd fluid get fire?
75ºC
What is the minimum pressure for brakes application?
70bar
But w/ 50 bar a minimum of 10 brakes application should be granted
