Hydraulic

Question 1

What is the function of system accumulator ?

Answer 1

Maintain a constant pressure by covering transient demand during normal operation

Question 2

What is normal pressure in hydraulic ?

Answer 2

3000 psi (2500 psi when powered by RAT)

Question 3

How many hydraulic system are there ?

Answer 3

Green, Blue, Yellow

Question 4

Can hydraulic fluid be tranffered from one system to another ?

Answer 4

No

Question 5

How many source does GREEN system has ?

Answer 5

-Engine driven pump
-PTU

Question 6

How many source does BLUE system has ?

Answer 6

-Electrical pump
-RAT

Question 7

How many source does YELLOW system has ?

Answer 7

-Engine driven pump
-Electrical pump
-Hand pump
-PTU

Question 8

What is PTU ?

Power Tranfer Unit

Answer 8

A bidirectional power tranfer unit enable yellow system to pressurize green system and vice versa

Question 8

When will PTU work automatically ?

Power transfer unit

Answer 8

When differential btw Green and Yellow is more than 500 psi

Question 9

What is RAT ?

Answer 9

Ram Air Turbine, supplies pressure to Blue system and run emergency electric generator

Question 10

When will RAT be deploy ?

Ram air turbine

Answer 10

-Automatically when lost AC 1 and AC 2
-Manualy by RAT MAN ON pb on Hydraulic panel and Emer electric panel

Question 11

What is the diff of RAT MAN ON pb btw Hydraulic panel and Emer electric panel ?

Answer 11

-Pb on Hydraulic panel will only supplies hyrdraulic pressure to Blue
-Pb on Emer elec panel can supplies both hydraulic and electric.

Question 12

What is priority valves ?

Answer 12

it can cut off hydraulic power to heavy user if hydraulic power get low.

Question 13

Which systems are lost when priority valves close ?

* Green
* Yellow
* Blue

Answer 13

• Green: L/DG, slats,flaps
• Yellow: Flaps
• Blue: Emer Gen, Slats

Question 14

What is the function of Fire Shut Off Valves ?

Answer 14

Located at upstream of engine driven pump, close when push ENG FIRE pbs to cut out hydraulic supply

Question 15

What is Leak Measurement Valves ?

Answer 15

Locate upstream of primary flight control, which measure the leakage in each circuit.

Question 16

How is hydraulic reservoir pressurized ?

Answer 16

Reservoir is pressurized by HP bleed air from engine 1 automatically. If bleed air press is too low, system will take bleed air press from cross bleed duct.

Question 17

Why reservoir need to be pressurized ?

Answer 17

To prevent their pump from caviating

Question 18

Which systems are supplied only from GREEN ?

Answer 18

• L/DG
• REV ENG 1
• Norm BRK

Question 19

Which systems are supplied only from BLUE ?

Answer 19

EMER GEN

Question 20

Which systems are supplied only from Yellow ?

Answer 20

• ALT/PARK BRK
• Cargo Door
• REV ENG 2
• NWS

Question 21

FAULT lt in ENG PUMP pb ?

Answer 21

-Reservoir low level
-Reservoir low air press
-Reservoir overheat
-Pump press is low
Light go out when selected OFF except overheat

Question 22

BLUE ELEC PUMP pb

-FAULT lt

-AUTO

Answer 22

AUTO: if AC power avail, electric pump operate
- In flight
- On ground when one engine run or BLUE PUMP OVRD pb pushed

FAULT lt
-Reservoir low level
-Reservoir low air press
-Reservoir overheat
-Pump press is low
-Pump overheat
Light go out when selected OFF except overheat

Question 23

When will Yellow electric pump come on automatically ?

Answer 23

when operate cargo door

Question 24

What happen in yellow system during cargo door operation ?

Answer 24

Other operations of yellow system are inhibited (except alternate brk and engine 2 rev)

Question 25

FAULT lt in YELLOW ELLEC PUMP pb ?

Answer 25

-Reservoir low level
-Reservoir low air press
-Reservoir overheat
-Pump press is low
-Pump overheat
Light go out when selected OFF except overheat

Question 26

When is PTU inhibited ?

Answer 26

-First engine start
-During and 40s after cargo door operation

Question 27

How long does it take for RAT to extend and provide power ?

Ram air turbine

Answer 27

3s for extend, 5s for powering. Total 8s

Question 28

Can RAT be stowed affter depploy ?

Answer 28

No, only on ground

Question 29

During start up, when is BLUE system pressurized ?

Answer 29

Automatic after first engine start

Question 30

Why you need to turn off PTU first when reservoir overheat ?

Answer 30

To avoid PTU pressurize the faulty system which will worsen the situation.

Question 31

What does the amber level indication mean on the hydraulic quantity indicator ?

Answer 31

Warning level

Question 32

When brake accumulator press is low, how can you recharge ?

Answer 32

Request clearence from ground then turn on the yellow electric pump

Question 33

What happen with slats/flaps operation speed when lost 1 hyraulic press system ?

Answer 33

Green: 1/2 speed both
Yellow: 1/2 speed flaps
Blue: 1/2 speed slats

Question 34

What does the BRAKES & ACCU PRESS triple indicator indicate ?

Answer 34

-Yellow press delivered to the brakes
- Yellow brake Accumulator press

Question 35

How do you perform the brake check during initail taxi ?

Answer 35

Press the brake pedals to ensure a/c slow, and check the pressure on triple indicator is zero, indicating normal brake is working.

Question 36

Can the a/c be flown with a loss of all hydraulic system ?

Answer 36

No, need at least 1 system

Question 37

What is the purpose of hand pump ?

Answer 37

To provide yellow system hydraulic press to operate cargo door

Question 38

FAULT lt in PTU pb ?

Answer 38

-Reservoir low level
-Reservoir low air press
-Reservoir overheat
Light go out when selected OFF except overheat

Question 39

If FAULT lt in PTU pb is illuminate, are there any other indications on HYD panel ?

Answer 39

Yes, FAULT lt of respective ENG PUMP pb illuminate