Pneumatics

Question 1

What is the pneumatic system used for?

Answer 1

1. Air Con
2. Engine starting
3. Wing anti ice
4. Water pressurisation
5. Hyd pressurisation
6. Cargo heating (if installed)

Question 2

What are the three sources of bleed air?

Answer 2

1. Engines 1 and 2
2. APU
3. HP Ground Connection

Question 3

What computers control and monitor the pneumatic system?

Answer 3

2 x Bleed Monitoring Computers (BMC1 and BMC2)

Question 4

What does the cross bleed duct do?

Answer 4

1. Interconnects the 2 Engine Bleed Systems
2. Receives air from the APU and ground sources when appropriate

Question 5

Engine bleed system:

Answer 5

1. Selects a compressor stage as a source of air
2. Regulates bleed air temperature and pressure

Question 6

When do the engine bleed valves open

Answer 6

1. Engine bleed valves open pneumatically when engine bleed pressure is above 8 PSI and the APU bleed valve is closed

Question 7

What pressure stage of the engine normally supplies air to pneumatic system?

Answer 7

The intermediate pressure stage

If pressure drops, due to low engine speed, the high pressure valve opens to maintain pressure PSI

Question 8

How is the engine bleed air limited to 200 degrees?

Answer 8

1. By the engine pre cooler (which utilisers the Fan Air Valve)

Question 9

What happens if you select the ENG BLEED pb switches to off?

Answer 9

1. Engine bleed valves will close
2. The HP valve will close

Question 10

When will the ENG 1 BLEED and ENG 2 BLEED pbs have an Amber “Fault” light on?

Answer 10

1. Bleed over pressure
2. Bleed overheat
3. Pneumatic leak
4. Engine bleed valve not closed (during engine start or if pb selected to on)

Question 11

BLEED SD page - when are the valves in Amber?

Answer 11

When they have not engaged the commanded position the pilot has selected

Question 12

What does the APU bleed valve do?

What does the APU load compressor do?

Answer 12

1. Bleed valve - operates as a shut off valve
   a) controlled via APU BLEED pb on air con overhead panel
   b) can be selected on when APU speed is above 95%
2. Compressor - regulates the bleed pressure

Question 13

What are the conditions for the APU bleed valve to open?

Answer 13

1. APU at normal speed
2. No leak detected
3. APU BLEED pb - “on” (blue)

Question 14

How many Bleed Monitoring Computers are there and what do they control?

Answer 14

Total of 2 (have info on pressure, temp and valve position and send warnings to ECAM)

1. 1 x BMC (left side of the bleed air system
2. 1 x BMC (right side of the bleed air system)

In event of failure of one BMC - the other will take over most of the monitoring functions of the failed BMC

Question 15

What does the Crossbleed Valve do?

Answer 15

It either isolates or interconnects the crossbleed duct (ie connects the two separate sides of the pneumatic system)

Normal. The valve is normally closed when the engines are running to isolate the two sides of the pneumatic system

Question 16

X BLEED Selector Swith (overhead panel - air con). What are the three modes and what do they do?

Answer 16

1. AUTO. Aims to use the APU bleed air when available instead of the engines. Done via:
   a) opening APU bleed valve (if pb pressed to on)
   b) opening cross feed valve
   c) both engine bleed valves close
2. SHUT
   a) crossbleed valve closes
3. OPEN
   a) crossbleed valve opens

Question 17

Where are the leak detection loop locations?

Answer 17

1. Fuselage (double loop)
2. Wings (double loop)
3. Engine Pylons (single loop)
4. APU duct (single loop)

Leaks are detected by overheat from leaks in vicinity of hot air ducts

Question 18

How is a leak in engine pylon and Wing Leak sent to cockpit?

Answer 18

Amber fault light on ENG 1 BLEED or ENG 2 BLEED (depending which side is detected)

Question 19

How is an APU Duct leak warning sent to cockpit?

Answer 19

Amber “FAULT” light on APU BLEED pb

Question 20

Normal pneumatic procedures / checks

Answer 20

1. Air Con panel:
   a) ENG 1 BLEED Pb (on)
   b) APU BLEED pb (on - blue)
   c) X BLEED selector - AUTO
   b) ENG 2 BLEED pb - on
2. When APU BLEED pb switch set to on- the following is shown on ECAM BLEED page:
   a) APU bleed valve opens
   b) Cross bleed valve opens (supply to both sides of the pneumatic system)
   c) you can see pneumatic pressure available just before both ENG 1 and ENG 2
   d) ENG 1 and ENG 2 valves are closed (ready for engine start)
3. Once engines have started - APU BLEED pb - set to off (closing APU BLEED valve). Therefore, pneumatic systems powered by the engines (not the APU)

Question 21

External air start

Answer 21

Update if covered in lessons

Question 22

Abnormals - cautions etc

Answer 22

Update if covered in class