Pneumatic

Question 1

HP and Bleed valve pressures

Under what pressure does bleed valve close?

Answer 1

HP valve: 36 ± 4
Bleed valve 45 ± 5
may reach 56 at high thrust

Under 8 PSI or return flow

Question 2

Under what conditions does the bleed valve close automatically?

Answer 2

• BLEED pb
• ENG FIRE pb
• High temp / pressure
• Leak
• Starter on
• No bleed consumers

Question 3

Precooler outlet temperature target?
When is overheat triggered?

Answer 3

200ºC

255-290ºC (time dependent)

Question 4

When X-bleed in AUTO, what happens with APU bleed?

Answer 4

X-bleed AUTO:
Shuts when APU bleed being used

• !!! Set to MAN before using APU BLEED for Pack 1 after ENG 2 Fail

Question 5

Why might the Engine # be amber?

Answer 5

N2 below idle