Hydraulic

Question 1

Hydraulic systems 1,2and 3 have a normal pressure of?

Answer 1

3000 psi

Question 2

Low pressure (caution) appears at what pressure?

Answer 2

1800

Question 3

High pressure occurs at what pressure?

Answer 3

3200 psi

Question 4

What is the normal system quantity?

Answer 4

45% to 85%

Question 5

High temperature condition occurs at what temp?

Answer 5

> _ 96° C

Question 6

The HYD HI TEMP caution indicates that hydraulic fluid is hot in what part of the system?

Answer 6

The reservoir

Question 7

How many hydraulic pumps are there?

Answer 7

6 total
3 - full time “A” pumps
3 - part time “B” pumps

Question 8

When are the “B” pumps active?

Answer 8

Switch is ON or
With switches in AUTO
At least one generator on line and flaps > 0

Question 9

When will hydraulic pump 3B operate?

Answer 9

Switch ON or
Switch in AUTO or
At least one generator on line and flaps>0 or
ADG deployed

Question 10

What type of hydraulic fluid is used?

Answer 10

Skydrol

Question 11

What color is the hydraulic fluid?

Answer 11

Purple

Question 12

When will pressure relief occur?

Answer 12

> _ 3750 psi

Question 13

How many separate hydraulic systems are there in the CRJ 900?

Answer 13

Three

Question 14

Where are hydraulic systems one and two located?

Answer 14

Aft equipment bay

Question 15

How are hydraulic systems one and two cooled?

Answer 15

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

Question 16

How many pumps do system one and system to have

Answer 16

Main pump A (engine driven pump, EDP). 1A and 2A

Backup pump B (electric AC motor pumps- ACMP). 1B and 2B

Question 17

Which hydraulic system is the largest

Answer 17

3

Question 18

When do the main pumps operate

Answer 18

1A and 2A are engine driven and operate any time the associated engine is running

Question 19

When do back up pumps 1B and 2B -ACMP -AC motor pumps operate

Answer 19

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

Question 20

What is a hydraulic accumulator in which systems have it

Answer 20

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

Question 21

How do you stop the flow of hydraulic fluid between the Reservoir and the EDP?

Answer 21

You can either press the L or R HYD SOV switch OR ENG FIRE PUSH switch

Question 22

What is special about pump 3A

Answer 22

It only has on and off there, is no AUTO

Question 23

What is special about pump 3B

Answer 23

3B is automatically powered by the ADG bus during AC failure

Question 24

What modes do you pump 3B have

Answer 24

Auto- When:
bus is powered
any generator is operating
flaps greater than zero

Manual

On

Question 25

What does hydraulic system three power

Answer 25

``` Rudders Elevators Ailerons Inboard ground spoilers Inboard brakes Nosewheel steering Landing gear ```

Question 26

Where is system 3 located

Answer 26

Hydraulic compartment. | It has an accumulator that delivers to the ACMPs the same as the other two systems, and the largest Reservoir

Question 27

How is system three hydraulic cooled

Answer 27

It relies on natural convection to dissipate heat because it’s not near any appreciable heat source

Question 28

What are the hydraulic system limitations

Answer 28

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

Question 29

How many total hydraulic system accumulators are there

Answer 29

5 One for each hydraulic system And one for each brake Charged with dry nitrogen Dampens pressure surges

Question 30

When do you wanna be in to be turned on during auto mode

Answer 30

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