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Flashcards in Hydraulics COPY Deck (42)
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2

What is the function of the system accumulators?

An accumulator in each system helps to maintain a constant pressure by covering transient demands during normal operation.

3

When does the RAT extend automatically?

The RAT extends automatically if AC BUS 1 and AC BUS 2 are lost.

4

What is the function of the fire shutoff valves?

Each of the green and yellow system has a fire shutoff valve in its line upstream of its engine-driven-pump. The flight crew can close it by pushing the ENG1(2) FIRE pb. Basically it cuts off hydraulic fluid supply to the engine pump in the case of a fire.

5

How many hydraulic systems has the A320?

The aircraft has three hydraulic systems referred to as GREEN BLUE and YELLOW.

6

What does the RAT MAN ON switch do?

Extends RAT, pressurizes BLUE system, does not start Emergency Generator.

7

What is the function of the Power Transfer Unit (PTU)?

The bidirectional PTU enables the yellow system to pressurize the green system and vice versa. Comes on automatically when pressure diff between yellow and green > 500psi

8

You get a G RSVR OVHT message. Why does the ECAM procedure ask you to switch off the PTU first?

To prevent the PTU from pressurizing the GREEN system.

9

Why are the hydraulic reservoirs pressurized with bleed air?

Normally HP bleed air from engine 1 pressurizes the hydraulic reservoirs automatically to maintain a high enough pressure to prevent their pumps from cavitating.

10

Can you transfer hydraulic fluid between the hydraulic systems?

No hydraulic fluid cannot be transferred from one system to another.

11

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

The warning level. (low level fluid)

12

Describe the following conditions of the ENG 1 (2) PUMP pb (HYD Panel)

- ON
- OFF
- FAULT Light

ON:
Pump is on when the engine is running. (default position)

OFF:
The pump is depressurized.

FAULT Light:
With ECAM caution if:
- Reservoir low level
- Reservoir overheat (stays on while condition lasts)
- Reservoir low air pressure
- Low pump pressure (inhibited on the ground, when the engine is stopped)

13

Describe the following conditions of the BLUE ELEC PUMP pb (HYD Panel)

- AUTO
- OFF
- FAULT Light

AUTO:
If AC power is available, the electric pump operates:
- In flight
- On the ground, if one engine is running.

OFF:
The pump is de-energized.

FAULT Light:
With ECAM caution if:
- Reservoir low level
- Reservoir low air pressure
- Reservoir overheat (stays on while condition lasts)
- Pump low pressure (inhibited on the ground, when the engines are stopped)
- Pump overheat

14

Describe the following conditions of the YELLOW ELEC PUMP pb (HYD Panel)

- ON
- OFF
- FAULT Light

ON:
Electric pump is ON. If the electrical power supply is removed, the pump remains off when electrical power is applied again.

OFF: (default)
The pump is off. It comes on automatically during cargo door operation. This inhibits the operation of other yellow system functions (except alternate braking and engine 2 reverse).

FAULT Light:
With ECAM caution if:
- Reservoir low level
- Reservoir low air pressure
- Reservoir overheat (stays on while condition lasts)
- Pump low pressure
- Pump overheat

15

Describe the following conditions of the PTU pb (HYD Panel)

- AUTO
- OFF
- FAULT Light

AUTO:
The power transfer unit is armed and both the Y and G electrohydraulic valves are open. PTU runs automatically when the differential pressure between the green and yellow systems is > 500 PSI.
Inhibited:
- during the first engine start, (split MASTER SW + parking break or NWS disconnected)
- during cargo door operation, and after that for 40 sec
Automatically tested during the second engine start.

OFF:
Both the green and the yellow PTU electrohydraulic valves close. Power
transfer stops.

FAULT Light:
With ECAM caution if:
- G or Y reservoir low air pressure
- G or Y reservoir low level
- G or Y reservoir overheat
(stays on as long as the overheat lasts).

16

Name several items that run from ONLY the GREEN system?

- Landing Gear

- Normal Brakes (including autobrake)

- Engine 1 Reverser

17

What is the function of they hydraulic priority valves?

Hydraulic power to the flaps, slats, landing gear, NWS, and emergency generator is cut off if the pressure drops below a predetermined value (High demand items). Basically it they make sure that primary flight controls stay powered.

18

Which hydraulic system supplies nose wheel steering?

Yellow (older MSNs may be on the green system)

19

What is the purpose of the RAM AIR TURBINE (RAT)?

A drop-out RAT coupled to a hydraulic pump allows the blue system to function if electrical power is lost or both engines fail. The RAT deploys automatically if AC BUS 1 and AC BUS 2 are lost and It can be deployed manually from the overhead panel. It can be stowed only when the aircraft is on the ground.

20

When brake accumulator pressure is low, how is it recharged?

With the Yellow hydraulic system electric pump

21

If NO hydraulic power is available can the THS be positioned?

No, the THS requires hydraulic power from the Green or Yellow systems (Mechanical backup means that the the trim and rudder controls are directly connected to the hydraulic valves, hence you still need hydraulic pressure to operate)

22

With only Green hydraulic system pressure available, will both the flaps and slats operate?

Yes, at 1/2 speed

23

Which hydraulic systems provide pressure to the brakes?

- Normal Brakes: GREEN

- Alternate Brakes: YELLOW backed up by a hydraulic accumulator

24

If you lose Green hydraulic pressure, will you have auto brakes?

No, not with the alternate brake system

25

What does the BRAKES & ACCU PRESS triple indicator indicate?

- Yellow hydraulic pressure delivered to the left and right brakes

- Yellow system brake accumulator pressure

26

How do you perform the brake check during initial taxi?

Press the brake pedals to ensure the aircraft slows, and check the brake pressure on the triple indicator is zero, indicating the Green hydraulic system has taken over

27

Can the aircraft be flown with a loss of all hydraulic systems?

No, you must have at least one

28

How many hydraulic pumps are in the GREEN system?

- 1 Engine driven pump

- 1 PTU

29

How many hydraulic pumps are in the BLUE system?

- 1 Electric pump

- 1 RAT

30

How many hydraulic pumps are in the YELLOW system?

- 1 Engine driven pump

- 1 Electric pump

- 1 PTU

- 1 Hand Pump

31

What is normal system hydraulic pressure?

3000 psi +/-200