Pneumatic, Bleed & Ventilation

Question 1

What are the 6 systems the pneumatic system provides high-pressure air for?

Answer 1

Air conditioning
Engine starting
Wing anti-icing
Water pressurisation
Hydraulic reservoir pressurisation

+Fuel Tank Inerting System (FTIS) *if installed

Question 2

What is a BMC? How many are there? What do they do?

Answer 2

Bleed Monitoring Computers (x2)

They control and monitor each engine bleed air system.

Question 3

What happens if one BMC fails?

Answer 3

The other takes over most of the monitoring functions

Question 4

Where is air normally bled from?

Answer 4

The intermediate pressure stage (IP) of engine’s high-pressure compressor - to minimise fuel penalty

Question 5

What is the precooler and what does it regulate the temperature to?

Answer 5

Air-to-air heat exchanger that uses cooling air bled from the engine fan to regulate the temperature to approx. 200°C

Question 6

What is the function of the leak detection system in the pneumatic system?

Answer 6

To detect any overheating near the hot air ducts in the fuselage, pylons, and wings.

Question 7

How many wing bleed leak detection loops need to detect a leak to activate a wing leak signal?

Answer 7

Two (or one if the other is inoperative)

Question 8

What 3 things happens automatically if a wing/pylon/APU bleed leak is detected?

Answer 8

1) Bleed valve on the related side closes
2) FAULT light on associated pb on AIR COND panel
3) XBLEED valve closes (except during engine start)
APU bleed valve closes (if it was open, and the leak concerns the left wing, pylon 1, or the APU)

Question 9

What position should the RAM AIR inlet flap be on the ground? What about in flight?

Answer 9

Closed on the ground to prevent FOD, fully open in flight

Question 10

What happens to ENG bleeds and crossbreed valve if APU bleed selected?

Answer 10

ENG bleeds close and APU bleed takes priority. Cross bleed value in AUTO mode goes to open.

Question 11

Is APU bleed authorised for wing anti ice?

Answer 11

No. It’s not hot enough.

Question 12

If ENG 2 FIRE PB pressed, can APU bleed be used?

Answer 12

Yes, providing crossbleed closed. APU is on the left hand side (ENG1 side of cross bleed valve)

Question 13

If ENG 1 FIRE PB pressed, can APU bleed be used.

Answer 13

No. APU bleed is on contaminated side.

Question 14

What does the pressurisation system do during take off?

Answer 14

Increase cabin pressure to avoid surge at rotation

Question 15

How many motors does the outflow valve have?

Answer 15

3
2x auto
1 for manual

Question 16

Describe the different modes of the ventilation system

Answer 16

Open.
Ground, when duct temp >40°
Skin Air Inlet/Outlet open.

Closed.
Ground, duct <40° or Flight, low skin temperature.
Skin Air Inlet/Outlet closed, other valves open.
Air drawn from avionics bay, exhausted into underfloor of cargo bay.
Also return loop vía skin heat exchanger.

Intermediate.
In flight, high skin temperature.
Skin Air Extract valve partially open.

Smoke.
Both fans set to OVRD - Blower fan stops, Extract fan runs. Same as Open Config except Air Con supplies air rather than from outside

Question 17

What happens when BLOWER and/or EXTRACT set to OVRD?

Answer 17

Blower to OVRD - fan stops.
Extract to OVRD - fan directly controlled by pb. Both fans run.

When either pressed, system goes to Closed config but air supplied from AIR CON duct