HYDRAULICS

Question 1

How many Hydraulic Systems ?

Answer 1

Three independent 5000psi hydraulic systems

LEFT RIGHT CENTRE ( Main)

Question 2

How is the Centre Hydraulic System powered?

Answer 2

The Centre System is powered by TWO large electric driven hydraulic pumps

Question 3

The Centre Hydraulic system is powered by two electric pumps. When do they run ?

Answer 3

One runs throughout the entire flight and the other pump only runs during Take off and landing

Question 4

If you lose all three hydraulic systems what flight controls do you have ?

Answer 4

Two spoiler panels on each wing ( electrically powered )
Stabiliser trim ( electrically powered).
NO Flaps

Question 5

Loss of ALL hydraulics AND ALL Generators ?

Answer 5

Flight Control power comes from separate Permanent Magnet Generators (PMGs) which produce power even if engines quit and are windmilling

Question 6

What happens if the PMGs fail ?

Answer 6

Flight controls will be powered by 28 v Standby Bus

Question 7

Six system powered by Hydraulics ?

Answer 7

Flight Controls
Thrust Reverser
Wing spoilers
Nose wheel steering
Gear
Flaps and slats

Question 8

List the Hydraulic Pumps

Answer 8

Left and Right Engine driven pumps

Left and Right Hydraulic System demand pumps

Question 9

When will the EMP (Electric Motor Driven) Demand pumps operate?

Answer 9

Provide Supplementary hydraulic power for periods of high system demand. Operate when:

System low pressure
For 3 mins after second engine start
T/O Thrust to Flaps Up
Descent Flaps to SB stowed (Left Pump Only)
Thrust Reverser Operation

Question 10

When does the DEMAND PUMP FAULT lights illuminate (Amber)?

Answer 10

Low Demand Pump pressure
High Temperature
Demand Pump is selected Off

Question 11

What is the RAT capable of powering ?

Answer 11

The RAT can provide hydraulic power to the centre hydraulic system primary flight controls only

Question 12

How do the Centre Hydraulics pumps configure themselves ?

Answer 12

They alternate as a Primary Pump and a Demand Pump.
Primary Pump operates continuously
Centre Demand Pump operates under the following conditions :

• system low pressure
• T/O thrust to Flaps Up
• Flaps and Slats Not up
• Gear not up

Question 13

What two types of pumps are there ?

Answer 13

Engine Driven and Electrically driven pumps operating at 5000 psi