Pneumatics

Question 1

What uses the bleed system?

Answer 1

Air conditioning
Engine starting
Anti ice
Water pressure
Hydraulic reservoir pressure

Question 2

What are the various bleed sources?

Answer 2

Engine IP stage (compressor stage 5)

Engine HP stage (compressor stage 9)
When IP not sufficient. Delivers 36psi +/-4psi

APU bleed [PRIORITY]

Question 3

What happens after air is tapped from engine?

Answer 3

BMC uses air from either IP or HP stage (one way valve prevents HP air entering IP stage)
It then passes through a bleed valve and then a precooler which cools the air to approx 200*C.
It can now be used for its various bleed demands

Question 4

Describe the APU bleed system

Answer 4

APU bleed has priority over others when pressed on overhead panel
The APU bleed valve opens, the cross bleed opens and the engine bleed valves close
APU bleed supplies engine 1 side

Question 5

How is bleed system affected following loss of engine?

Answer 5

Engine flame out:
• cross bleed can be opened
• both packs can be run
• WAI available if one pack turned off

Engine fail with damage or engine fire:
• keep cross bleed shut
• WAI unavailable

Above max landing weight with engine damage:
• approach should be made flap 3 with engine bleeds off and APU bleed on for air con

Question 6

Where is EAI bleed air tapped from?

Answer 6

It is tapped independently from the HP compressor and controlled by a spring loaded valve moved by pushing the pb in the overhead panel