Pneumatics

Question 0

HPV high pressure valves consist of?

Answer 0

6th and 10th stages of the engine.

Question 1

Engine bleed valves are pneumatically operated and electronically controlled by associated ACSC.

Answer 1

True.

Question 2

HPV closes when?

Answer 2

Upstream bleed pressure is less than 13psi.

Control signal is removed either automatically or manually.

ENG/FIRE PUSH switch light is pushed.

Question 3

Isolation valve

Answer 3

Provides interconnection and isolation capabilities between left and right sides of the bleed air manifold.

Question 4

ECS (environmental control systems) does what?

Answer 4

Provides conditioned air to passenger cabin and flight deck.

Question 5

Available ECS options?

Answer 5

Aft Cargo bay heat

External low pressure conditioned air connection.

Question 6

Conditioned air enters the cabin where? And recirculated air?

Answer 6

At the ceiling, sidewalls and PSU gaspers and exhausted at floor level
Supplementary galley heating is controlled at the galley control panel

Collected at sidewall sills in the passenger cabin
– Uses dedicated left and right recirculation ducts
Controlled by a single switch on the
AIR-CONDITIONING
control panel

Question 7

APU/ engine bleed Switching

Answer 7

If APU operating during takeoff, switch to engine bleed
occurs with gear up and flaps 20Degrees or less, and Thrust
Levers retarded from TOGA
On approach, transfer from engines to APU occurs when
flaps greater than 20Degrees or landing gear down
ACSC will not allow APU to supply bleed air to wing
anti-ice systems.

Question 8

Engine start sequence

Answer 8

Isolation valve opens
Both pack valves close
Associated start valve opens
Engine air turbine starter (ATS) engages
At 50% N2:
– ATS disengages
– Start valve closes
– Pack valves and isolation valve return to previous 
setting.