Hydraulics

Question 1

Hydraulic operating pressure, minimum pressure & maximum pressure

Answer 1

Normal = 3000psi
Minimum = 2800psi
Maximum = 3500psi

Question 2

Where are the hydraulic reservoirs and electric pump’s located?

Answer 2

The wheel well

Question 3

How are hydraulic reservoirs pressurised and at what pressure?

Answer 3

Bleed air, 40-50psi

Question 4

How is the stdby hydraulic system replenished and pressurised?

Answer 4

Connected to the Hyd B system

Question 5

What type of hydraulic fluid is used?

Answer 5

BMS 3-11 type 4

Question 6

What type of hydraulic fluid is used?

Answer 6

BMS 3-11 type 4

Question 7

EMDP

Answer 7

Electric motor driven pump

Question 8

EDP

Answer 8

Engine driven pump

Question 9

How is the hydraulic low pressure light activated?

Answer 9

Illuminates when pressure drops below 1300psi, detected via the pressure module

Question 10

How is the PTU activated?

Answer 10

Pressure module pressure switch sends a low pressure signal to the PTU when the EDP pressure drops below 2350psi for more than 0.5 seconds

Question 11

How is the EMDP cooled and lubricated?

Answer 11

Via its own hydraulic fluid supply

Question 12

What transfer bus powers the HYD A EMDP?

Answer 12

XFR Bus #2

Question 13

What transfer bus powers the HYD B EMDP?

Answer 13

XFR BUS #1

Question 14

What transfer bus powers the STDBY EMDP?

Answer 14

XFR BUS #2

Question 15

EMDP output vs EDP

Answer 15

EMDP has 6x lower capacity output than the EDP

Question 16

EMDP operating limits

Answer 16

• 5 minute period - max 5 starts
• When switched off wait 30 seconds before restarting the pump

Question 17

How is the STDBY EMDP cooled?

Answer 17

Cooled by airflow from outside the aircraft

Question 18

Minimum amount of fuel in the main tank to provide cooling for hydraulic heat exchangers

Answer 18

760kg in the associated tank

Question 19

Cockpit hydraulic overheat light parameters

Answer 19

Illuminates at 113 degrees Celsius
Resets at 85-102 degrees Celsius

Question 20

What does the cockpit EDP switch control?

Answer 20

Controls the position of the depressurising valve

Question 21

Function of the pressure module

Answer 21

-Protects from overpressure
-low pressure warning
-Transmits pressure readouts to DEU

Question 22

What does a flight control package contain?

Answer 22

-Flight spoiler shut off valve
-Flight control shut off valve
-Pressure switch (low pressure warning)
-Optional compensator cartridge

Question 23

What is the purpose of the flight control package compensator cartridge?

Answer 23

Maintains 40-70psi of hydraulic pressure to primary flight controls when hydraulics are off. Providing gust protection.

Question 24

Cockpit hydraulic flight control switch functions:

Answer 24

Off: Ailerons, Elevator and rudder are hydraulically isolated. Low pressure light illuminates.

Stby: Ailerons, elevator and rudder are hydraulically isolated. Low pressure light is inhibited. Stby rudder is activated.

Question 25

Hydraulic A reservoir, in case of a leak in the EDP line and EMDP line:

Answer 25

EDP line: Reservoir quantity will reduce to 20% (standpipe reaching up to the first 20% of the reservoir, EDP prone to leaks) EMDP line: Reservoir quantity will reduce to 0%

Question 26

Hydraulic B reservoir, how much fluid is left if there is a leak?

Answer 26

Around 5 litres remain for PTU operation (EDP and EMDP have a common standpipe)

Question 27

If there is a leak in the standby line what will occur to hydraulic levels?

Answer 27

Hydraulic B reservoir will drop to 70%

Question 28

At what quantity will RF (Refill) be displayed?

Answer 28

76%

Question 29

Hydraulic reservoir quantities:

Answer 29

Hyd A: 25.8L (100%: 21.6L) Hyd B: 40.6L (100%: 31.1L) Stby: 13.3L

Question 30

Function of the PTU

Answer 30

Supplies additional volume of hydraulic fluid needed to operate autoslats and leading edge flaps at normal rate when system B EDP volume is lost

Question 31

What is the function of the landing gear transfer unit?

Answer 31

Designed to raise the gear at a normal rate after EDP A volume is lost

Question 32

What does the standby hydraulic system supply?

Answer 32

- Standby rudder PCU - Standby yaw damper - Leading edge flaps and slats (Extension only) - Thrust reversers

Question 33

Where is the standby EMDP located?

Answer 33

On the right aft wing to body fairing and cooled by outside air

Question 34

What is the power supply for the standby EMDP?

Answer 34

AC transfer bus 2

Question 35

When does the standby low quantity light illuminate?

Answer 35

Fluid quantity less than 50%