36 Pneumatic

Question 1

What are the 7 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

+Cargo hold heating *if installed (not at EZY)

Question 2

What are the 3 sources of high-pressure air?

Answer 2

Engine bleed systems
APU load compressor
HP ground connection

Question 3

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

Answer 3

Bleed Monitoring Computers (x2)

They control and monitor each engine bleed air system.

Question 4

How many engine bleed air systems are installed on the aircraft?

Answer 4

2

Question 5

What do the engine bleed air system computers do (BMCs)?

Answer 5

Select the compressor stage to use as a source of air, regulate the bleed air temperature and pressure

Question 6

What happens if one BMC fails?

Answer 6

The other takes over most of the monitoring functions

Question 7

Where is air normally bled from?

Answer 7

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

Question 8

At low engine speeds, when the temperature and pressure of the IP air is too low, where is bleed air bled from?

Answer 8

HP stage (maintained at 36+/-4psi)

NEO: HP stage (maintained at 65+/-15psi)

Question 9

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

Answer 9

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

Question 10

Above what APU N% speed will the APU bleed air system supply the pneumatic system?

Answer 10

95% (when AVAIL shows on APU SD page)

Question 11

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

Answer 11

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

Question 12

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

Answer 12

Two (or one if the other is inoperative)

Question 13

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

Answer 13

Bleed valve on the related side closes
FAULT light on associated pb on AIR COND panel
Crossbleed 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 14

When does the precooler inlet pressure become amber?

Answer 14

Below 4psi or above 57-60psi (set by BMC)

Question 15

When does the precooler outlet temperature become amber?

Answer 15

> 290 degC for more than 5 seconds
270 degC for more than 15 seconds
257 degC for more than 55 seconds

or

<150 degC

Question 16

When does the pack outlet temperature become amber?

Answer 16

Above 90 degC

Question 17

When does the pack compressor outlet temperature become amber?

Answer 17

Above 260 degC

Question 18

How accurate is the pack flow indicator?

Answer 18

Indication can be up to 30% below the actual flow rate

FCOM DSC 21-10-50

Question 19

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

Answer 19

Closed on the ground, fully open in flight

Question 20

What are the three triangles indicating at the top of the BLEED SD page?

Answer 20

User indication (amber if, in flight, the RAM AIR flap is not fully open in addition to the pack flow control valves being closed)

FCOM DSC 21-10-50

Question 21

On the BLEED SD page, from top to bottom, what are the four numerical figures indicating on each bleed system?

Answer 21

Pack outlet temperature
Pack compressor outlet temperature

Precooler inlet pressure
Precooler outlet temperature

Question 22

When does the ANTI ICE indicator turn amber on the BLEED SD page?

Answer 22

Pressure too high or too low, or

Open on the ground for more than 10 seconds (WAI on)