Hydraulic Flashcards
Hydraulic systems 1,2and 3 have a normal pressure of?
3000 psi
Low pressure (caution) appears at what pressure?
1800
High pressure occurs at what pressure?
3200 psi
What is the normal system quantity?
45% to 85%
High temperature condition occurs at what temp?
> _ 96° C
The HYD HI TEMP caution indicates that hydraulic fluid is hot in what part of the system?
The reservoir
How many hydraulic pumps are there?
6 total
3 - full time “A” pumps
3 - part time “B” pumps
When are the “B” pumps active?
Switch is ON or
With switches in AUTO
At least one generator on line and flaps > 0
When will hydraulic pump 3B operate?
Switch ON or
Switch in AUTO or
At least one generator on line and flaps>0 or
ADG deployed
What type of hydraulic fluid is used?
Skydrol
What color is the hydraulic fluid?
Purple
When will pressure relief occur?
> _ 3750 psi
How many separate hydraulic systems are there in the CRJ 900?
Three
Where are hydraulic systems one and two located?
Aft equipment bay
How are hydraulic systems one and two cooled?
Cooled by air/ oil heat exchanger located in AFT equipment bay
Air from ram air scoop is directed across heat exchanger
On the ground and electric fan inside the heat exchanger draws air from ram scoop for cooling
How many pumps do system one and system to have
Main pump A (engine driven pump, EDP). 1A and 2A
Backup pump B (electric AC motor pumps- ACMP). 1B and 2B
Which hydraulic system is the largest
3
When do the main pumps operate
1A and 2A are engine driven and operate any time the associated engine is running
When do back up pumps 1B and 2B -ACMP -AC motor pumps operate
They are controlled by switch is Off, Auto and On
AUTO- Pumps will operate when:
their buses are powered
any generator operating
and flaps > zero
Manual-place switch to the ON position
1B and 2B DO NOT automatically start after engine or EDP failure
What is a hydraulic accumulator in which systems have it
Systems one and two have a hydraulic accumulator which hydraulic delivers hydraulic fluid under pressure to the EDPs and ACMPs.
One accumulated per system stores hydraulic pressure, gas charged with dry nitrogen
How do you stop the flow of hydraulic fluid between the Reservoir and the EDP?
You can either press the L or R HYD SOV switch OR ENG FIRE PUSH switch
What is special about pump 3A
It only has on and off there, is no AUTO
What is special about pump 3B
3B is automatically powered by the ADG bus during AC failure
What modes do you pump 3B have
Auto- When:
bus is powered
any generator is operating
flaps greater than zero
Manual
On
What does hydraulic system three power
Rudders Elevators Ailerons Inboard ground spoilers Inboard brakes Nosewheel steering Landing gear
Where is system 3 located
Hydraulic compartment.
It has an accumulator that delivers to the ACMPs the same as the other two systems, and the largest Reservoir
How is system three hydraulic cooled
It relies on natural convection to dissipate heat because it’s not near any appreciable heat source
What are the hydraulic system limitations
Each system is normally pressurized at 3000 PSI.
Low pressure caution at 1800
High pressure caution at 3200
High pressure relief at 3750
Normal system level 45 to 85%
High temperature caution at 96° C
Hydraulic fluid type is Skydrol
How many total hydraulic system accumulators are there
5
One for each hydraulic system
And one for each brake
Charged with dry nitrogen
Dampens pressure surges
When do you wanna be in to be turned on during auto mode
When flaps are greater than zero and at least one generator is online
By having it in auto that ensures hydraulic power will be available during high demand
1B and 2B do not turn on automatically if low pressure exists
