Pneumatics

Question 1

What does the amber “VALVE” light on the isolation valve switch and APU bleed valve switch indicate?

Answer 1

Valve position disagrees with switch position.

Question 2

What does the amber “OFF” light on the bleed valve switches indicate?

Answer 2

Engine bleed air valve and HP bleed air valve are commanded close.

Question 3

How is pneumatic low pressure indicated?

Answer 3

Amber

White-12 PSI and above.
Amber-11 PSI and below

Question 4

Where is engine bleed air supplied from?

Answer 4

High pressure stage 10 or intermediate pressure stage 4.

Question 5

Which valves will open when the bleed air switch is selected on?

Answer 5

Engine bleed air valves remain closed until sufficient pressure for forward flow.

Question 6

How are the bleed air valves actuated?

Answer 6

Pressure actuated and remain closed until engine bleed air pressure is sufficient to provide forward flow.

Question 7

Which valves will close When bleed air overhears and how is it reset?

Answer 7

Engine bleed valve (PRSOV) plus HPSOV plus respective isolation valve.

Can be reset once temperature cooled down.

Question 8

Which valve remains closed during engine start?

Answer 8

Engine bleed air valve

Question 9

When does the high pressure shutoff valve open?

Answer 9

During descent and other low power operations.

Question 10

What happens when there is a duct leak in the APU bleed air system? Can APU be re-started?

Answer 10

APU automatically shuts down

APU on EICAS.

“APU DUCT LEAK” on APU page.

Cannot be re-started.

Question 11

What is the isolation valve switch normal position? What does the VALVE light indicate?

Answer 11

OPEN

Isolation valve position disagrees with switch position.

Question 12

List the sources and users of center bleed air system.

Answer 12

Source: APU

USERS: Pack 2- Aft and bulk cargo heating.

Question 13

What does NGS system supply to the fuel tank and which pneumatic manifold supplies it?

Answer 13

Converts bleed air into nitrogen rich air to prevent flammability of centre wing fuel tank.

Right manifold.

Question 14

What causes NGS system to stop operating?

A. On ground?

B. Non-normal conditions?

Answer 14

• Engine our operations.
• Equipment cooling equipment in OVRD.
• Right bleed air duct isolated.
• Cargo Fire Switch armed.

After landing above 16 degree: stays on for 7 minutes.

Below 16 degree: shuts down immediately.

Question 15

What causes BLD X TEMP message mean?

Answer 15

Engine bleed air temperature is too low to provide wing anti-ice.

Question 16

Is engine anti ice air available with the engine bleed air switch OFF?

Answer 16

Yes, as long as engine is running you can get EAI.

Question 17

What is the EICAS message when bleed air switch is selected OFF when engine is running?

Answer 17

BLEED X OFF