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Flashcards in Hydraulics Deck (55)
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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 normal pressure in the hydraulic system?

3000psi.

5

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.

6

How many hydraulic systems has the A320?

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

7

During start up when is the BLUE hydraulic system pressurized?

Automatically after first engine start.

8

What does the RAT MAN ON switch do?

Extends RAT pressurizes BLUE system does not start Emergency Generator.

9

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.

10

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.

11

Can you transfer hydraulic fluid between the hydraulic systems?

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

12

The PTU start running if the differential pressure between the green and yellow hydaulic system is ...

>500psi.

13

What is the purpose of the leak measurement valves?

Each hydraulic system has a leak measurement valve upstream of the primary flight controls. These valves which measure the leakage in each circuit are closed by operation of the LEAK MEASUREMENT VALVES pushbutton switch on the maintenance panel.

14

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 caviating.

15

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.

16

How many pumps are located within the YELLOW system?

Four elec pump engine pump PTU and hand pump.

17

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

The warning level.

18

What is the function of the priority valves?

Priority valves cut off hydraulic power to heavy load users if hydraulic pressure in a system gets low.

19

ENG 1 (2) PUMP pb
(HYD Panel)


- ON
- OFF
- FAULT Light

On:
Pump is on when the engine is running.


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)

20

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

21

YELLOW ELEC PUMP pb
(HYD Panel)

- ON
- OFF
- FAULT Light

(springloaded)

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

Off:
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

22

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).

23

RAT MAN ON pb
(HYD Panel)

The flight crew may extend the RAT at any time by pressing the RAT MAN ON pb.

24

Name several items that run from only the GREEN system?

- Landing Gear

- Normal Brakes

- Slats/Flaps

- Engine 1 Reverser

25

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)

26

What hydraulic system supplies nose wheel steering?

Yellow

27

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

With the Yellow hydraulic system electric pump

28

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

Yes, at 1/2 speed

29

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

No, the THS requires hydraulic power from the Green or Yellow systems

30

Which hydraulic systems provide pressure to the brakes?

- Normal Brakes: GREEN

- Alternate Brakes: YELLOW backed up by a hydraulic accumulator

31

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

No, not with the alternate brake system