Pneumatics

Question 1

What systems require bleed air?

Answer 1

Air Conditioning

Wing Anti-Icing

Engine Starting

Hyd reservoir pressurization

Water pressurization

Question 2

Where is the pressure supplied from?

Answer 2

Engine bleed
APU bleed or
External High Pressure ground connection

Question 3

Bleed air is usually supplied from the Intermediate Pressure stage except for…

Answer 3

Idle conditions where the High Pressure stage supplies the bleed air.

Note: IP and HP bleed is never used at the same time

Question 4

How is the bleed air cooled?

Answer 4

With a pre-cooler using cool air from the fan section

Question 5

What is the max altitude for APU bleed?

Answer 5

20,000 feet

Question 6

What side is the APU bleed connected to?

Answer 6

1 engine side, the crossfeed valve supplies APU bleed to both sides

Question 7

What is unique about APU bleed air priority?

Answer 7

The APU has priority supplying bleed air

Question 8

What is a limitation with the External High Pressure air connection?

Answer 8

When connected, DO NOT use any other bleed source!

Question 9

Where are the leak detection loops?

Answer 9

APU ducting
Engine Pylon ducting
Wing ducting

Question 10

What does BMC1 control?

Answer 10

Bleed air from Engine 1 and APU

Question 11

What is special about the wing ducting?

Answer 11

There are 2 leak detection loops in the wings. Each monitored by different BMCs. Both loops must detect a leak for a pilot alert. Otherwise, the leak is automatically isolated.

Question 12

Why would the Engine Number on the BLEED page be amber?

Answer 12

When the engine is below idele (off)

Question 13

What happens to the associated PACK when you manually close an engine bleed valve?

Answer 13

Turning off the engine bleed valve automatically shuts off the associated Air Conditioning PACK.

Question 14

How is the engine bleed valve closed by the pilot?

Answer 14

END BLEED pb OFF
OR
ENG FIRE pb engaged

Question 15

Why would the BMC close the engine bleed valve?

Answer 15

Over temp

Over Pressure

Bleed Leak

Engine Start sequence

APU Bleed selected ON

Question 16

How would Physics close the engine bleed valve?

Answer 16

No air pressure (spring loaded closed)

If reverse pressure is sensed

Question 17

When will the auto X BLEED valve open?

Answer 17

When APU bleed is selected on.

Question 18

What happens to the PACK control valve during engine start?

Answer 18

They automatically close to provide max pressure for engine start.

They will auto open ~30 seconds after start sequence

Question 19

If a engine bleed fails during icing conditions, what is a limitation?

Answer 19

One engine bleed CAN NOT operate both PACKs when de-icing is on

Question 20

During an engine bleed failure, can you use APU to supplement pressure?

Answer 20

NO, remember if you select APU bleed this will automatically close both engine bleed valves!

Question 21

What is a icing limitation during a bleed air leak?

Answer 21

You CANNOT XFEED bleed air because of the leak as this will feed it the leak. Since you do not want to de-ice only one wing, you must depart icing conditions.