DSC Pneumatic

Question 1

What are the sources of high pressure air ?

Answer 1

Engine bleed
Apu compressor
HP ground connection

Question 2

What control the engine bleed ?

Answer 2

Two BMC which regulate the pressure and temp and the selection of compressor stage (HP, IP)

Question 3

Where is the APU bleed connected ?

Answer 3

It is connected to the left of the x bleed valve

Question 4

From which compressor stage is the high pressure air normally coming from the ENG ? When is the other stage selected ?

Answer 4

it normally comes from the IP stage.
At low speed in case of pressure or temperature being too low, the BMC will connect the HP stage to maintain the pressure of 36PSI (CEO) or 65PSI(NEO)

Question 5

What is the purpose of the bleed valve ?

Answer 5

Act as a shutoff valve and pressure regulating valve

Question 6

What pressure is the bleed valve maintaining ?

Answer 6

45PSI+/-5(CEO), 42 +/-3PSI (NEO)

Question 7

What is the purpose of the precooler ?

Answer 7

Pre cool the bleed air temp via engine fan air to around 200°C

Question 8

When will the bleed valve be fully closed ?

Answer 8

• Pneumatically: Upstream pressure is below 8PSI (CEO) 15PSI (NEO) or return flow
• Electrically:
  o Bleed PB
  o Fire PB
  o BMC detect overtemp, over pressure, leak, starter valve, APU bleed ON.

Question 9

What is the priority for the bleed ?

Answer 9

APU bleed first then ENG bleed

Question 10

How is bleed leak detected ? Which area has a detection system ?

Answer 10

BMC1 and BMC2 detect overheating near the hot air ducts via detection loops.
the loops are located in :
- fuselage
- pylons
- wings

Question 11

Which systems has a dual bleed leak detection loop ?

Answer 11

the wings
pylons (NEO only)

Question 12

Which systems has a single bleed leak detection loop ?

Answer 12

APU
Pylons (except on NEO)

Question 13

What BMC is monitoring the APU bleed leak ?

Answer 13

BMC1 only

Question 14

When will the bleed leak signal trigger ?

Answer 14

dual loops leak detected or single loop with the other inop

Question 15

What will the wing leak or pylon leak signal causes ?

Answer 15

• Close bleed valve on this side
• Fault light
• X bleed close automatically (except start)
• for wing leak : Close the APU bleed valve if open and left-wing leak (except start), for pylon leak : close APU bleed valve if open and leak about pylon 1

Question 16

What will an APU leak signal causes ?

Answer 16

• APU bleed valve close (except start)
• Fault light
• X bleed (except start)

Question 17

What happen if you loose one BMC ?

Answer 17

the other takes over and can issue warning for
- overpressure
- over temp (not on NEO)
- wing leak

BUT you loose :
- Fault light on AIR cond panel (not on NEO)
- Auto close of bleed valve
- Eng bleed leak associated ENG (not lost on NEO)
- APU bleed leak if BMC1

Question 18

What is the impact on the crossbleed of using the ENG Fire PB ?

Answer 18

Any ENG Fire PB being pressed mean that you can no longer use the crossbleed
If ENG 1 Fire PB has been pressed the APU bleed can no longer be used (connected left of the crossbleed valve)

Question 19

What is supplied by the pneumatic system high pressure air ?

Answer 19

• Air conditioning
• Engine start
• Wing anti icing
• Water pressurization
• HYD reservoir pressurization

Question 20

What is the main operational consequence of a dual bleed fault ?

Answer 20

• Slow decompression
• Descend FL100
• May stop FL 200(qrh) if APU bleed is working => single pack
• Wing anti ice not available due to supply from APU
• AP and ATHR working

Question 21

In a single engine operation when can the APU bleed be available ?

Answer 21

you can use the APU bleed if the ENG Fire PB on the ENG 1 hasn’t been pressed.