Air

Question 1

What is bleed air used for?

Answer 1

• ECS (heating & cooling)
• Engine start
• Engine and wing anti-icing
• Water pressurization

Question 2

What is external pneumatic air used for?

Answer 2

• ECS on the ground

- Engine start on the ground

Question 3

Where is the external ground source panel located?

Answer 3

• Lower fairing between the wings

Question 4

What is the Primary use for APU Bleed Air?

Answer 4

• ECS on the ground
• Engine starting on the ground
• Assist with engine start (< FL210)
• Bleed source for pressurization, heating, and cooling (< 15,000 ft MSL)

Question 5

Can engine bleed air flow-back to the APU?

Answer 5

• No. A check valve prevents flow-back

Question 6

What is the Purpose of the Pre-cooler?

Answer 6

• Cools the bleed air coming from the engine to the AMS

Question 7

What does the Overheat Detection System (ODS) observe?

Answer 7

• Engine bleeds and packs
• APU bleed
• Plumbing for the wing and engine anti-icing system

Question 8

Is one Detection Loop capable of detecting an overheat condition?

Answer 8

• Yes (if one fails the other will work alone to detect the overheat)

Question 9

How many ECS packs are installed?

Answer 9

• 2 independent packs (left and right)

Question 10

Can a single ECS pack provide temperature control and pressurization?

Answer 10

Yes, but limited to operations at or below FL310

Question 11

Can a single Bleed Source power both ECS Packs?

Answer 11

• Yes, through the Crossbleed valve

Question 12

When are the Recirculation Fans commanded off?

Answer 12

• Cockpit switch
• Smoke detected in the recirc bay
• DUMP button is pressed
• Respective pack is commanded off

Question 13

When is the Emergency Ram Air Ventilation activated?

Answer 13

• Both packs commanded or failed OFF below 25,000 feet (via left side and
  electronically controlled)
• Ram air pressure greater than cabin pressure (via right side)