Hydraulic

Question 1

How many hydraulic systems are there ?

Answer 1

3 independant systems : GREEN - BLUE and YELLOW

Question 2

What is the normal operature pressure ?

Answer 2

3000 PSI

Question 3

What is the normal operature pressure when RAT extended ?

Answer 3

2500 PSI

Question 4

Can the hydraulic fluid be transfered from one system to another ?

Answer 4

No transfer of fluid between the system to prevent contamination

Question 5

What are the hydraulic pumps ?

Answer 5

GREEN : engine-driven by ENG 1
BLUE : electrical pump + another pump driven by the RAT in case of emergency
YELLOW : engine-driven by ENG 2 + electrical pump allows yellow system to be used on the ground with engines stopped. Crew can also use a handpump to operate the cargo door operation when electrical power is not available

Question 6

What is the role of the PTU ?

Answer 6

It enables to GREEN system to power the YELLOW system and vice versa

Question 7

When does the PTU come into action ?

Answer 7

If one system fails or if the pressure drops at least 500 PSI more than the other pump.

Question 8

What is the purpose of the priority valves ?

Answer 8

They are installed to maintain hydraulic pressure to the primary flight controls and cut off pressure to the heavy loads (landing gear for example) if the hydraulic pressure in a system gets low (during high demand)

Question 9

What is the purpose of the accumulators ?

Answer 9

They are designed to maintain a constant pressure by covering transcient demands

Question 10

How are the FIRE shut off valves activated ?

Answer 10

When the FIRE pb is pushed

Question 11

What is the purpose of the leak measurement valves ?

Answer 11

Upstream of the all the flight controls or system, they check the total leakage of the hydraulic components

Question 12

How is the reservoirs pressurized ?

Answer 12

Normally by the HP bleed air coming from the engine 1.
If bleed air pressure is too low, the system takes bleed air from the crossbleed duct.

Question 13

When is the YELLOW ELEC pump inhibited ?

Answer 13

When a ground crew sets the lever of the cargo doorr manual selector to OPEN to CLOSE, yellow elec pump automatically comes ON, which inhibits the other function of the yellow elec pump

Question 14

What is not included in the YELLOW ELEC pump inhibition ?

Answer 14

Alternate braking and engine 2 reverse.

Question 15

When is the PTU tested ?

Answer 15

After the second engine is started

Question 16

When is the PTU inhibited ?

Answer 16

• the YELLOW ELEC pump is operated to close the cargo door and is kept inhibited 40 seconds after the end of the cargo door operation
• the aircraft is on the ground with one engine runung and parking brake ON
• the aircraft is on the ground with one engine running, parking brake OFF and nose wheel steering deactivated
• the PTU pb is OFF
• During the first engine start

Question 17

What does the RAT MAN ON pb do on the HYD panel ?

Answer 17

It enables the crew to energize the emergency hydraulic pump ONLY. It does not activate the emergency electrical generator

Question 18

How many liters are there in normal filling in the reservoir ?

Answer 18

GREEN : 14,5L
YELLOW : 12,5 L
BLUE : 6,5 L

Question 19

When does the system pressure become amber on the SYS page ?

Answer 19

When pressure is below 1450 PSI

Question 20

When does the PUMP become amber on the SYS page ?

Answer 20

When N2 is below IDLE