ECS Questions

Question 1

What does the AMS use bleed air for?

Answer 1

• ECS (heating & Cooling)
• Engine start
• Pressurization
• Engine and wing anti-ice
• Water pressure
• Hot air leak detect

Question 2

How many AMS controllers are installed?

Answer 2

• One controller with 2 channels which control the respective onside system

Question 3

What happens if a channel fails?

Answer 3

• The remaining channel is able to control the entire AMS

Question 4

What provides air for the AMS?

Answer 4

• Engine bleeds
• APU bleed
• External pneumatic source

Question 5

What is bleed air used for?

Answer 5

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

Question 6

What is external pneumatic air used for?

Answer 6

• ECS on the ground

- Engine start on the ground

Question 7

Where is the external ground source panel located?

Answer 7

• Lower fairing between the wings

Question 8

What is the primary use for APU bleed air?

Answer 8

• ECS on the ground
• Engine starting on the ground
• Electrical source

Question 9

Can engine bleed air flow-back to the APU?

Answer 9

• No. A check valve prevents flow back

Question 10

Where is bleed air tapped from the engine?

Answer 10

• 6th and 10th stage compressors (EBV and HSV respectively)

- System alternates between valves to regulates and adequate and safe pressure.

Question 11

What is normal pressure for engine operation?

Answer 11

45 psi

Question 12

What is the purpose of the pre-cooler?

Answer 12

Cools the bleed air coming from the engine to the AMS

Question 13

What cools the pre-cooler?

Answer 13

• Ground N1 fan

- Flight N1 fan or ram air

Question 14

What does the overheat detection system (ODS) observe?

Answer 14

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

Question 15

Do both loops have to function in order to detect on overheat condition?

Answer 15

• Yes, but if one fails the other will work alone to detect the overheat

Question 16

How many ECS packs are on the airplane? What provides air for the packs?

Answer 16

• 2 independent packs (left & right)

- Each engine provides bleed air to its respective pack

Question 17

Can a single pack provide adequate temperature control and pressurization?

Answer 17

• Yes, up to FL310

Question 18

Can a single bleed source power both packs?

Answer 18

Yes, up to FL310

Question 19

What is the ratio of fresh air to recirculation air?

Answer 19

• 52% fresh air to 48% recirculated

Question 20

When are the recirculation fans commanded off?

Answer 20

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

Question 21

What keeps the 3 avionic E-BAY’s cool?

Answer 21

• FWD & CTR E-BAY 3 fans each pull air from cabin to bay

- AFT E-BAY natural air-flow from cabin to bay

Question 22

When is the Emergency Ram Air Ventilation activated?

Answer 22

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

Question 23

How many channels on the cabin pressure control (CPC)?

Answer 23

2 Channels, one active and one in standby mode

Question 24

Where dose the CPC get Landing Field Elevation (LFE)?

Answer 24

• FMS or can be manually selected

Question 25

What happens when the dump button is pressed?

Answer 25

- Commands both ECS packs off | - Opens OFV and raises the cabin to 12,400 ft at a rate of 2,000 FPM

Question 26

Can the cabin altitude be raised hight then 12,400 ft?

Answer 26

- Yes, by using manual mode | - Cabin altitude will rise due to natural leak

Question 27

In manual mode will the cabin depressurize on landing?

Answer 27

NO

Question 28

What is the bleed system priority in flight?

Answer 28

- Onside engine - Opposite side engine - APU (if available)

Question 29

If engine and APU bleed air are available simultaneously, which has priority?

Answer 29

- APU has priority if - Aircraft is on the ground - Wheel speed < 50 kts - Opposite engine bleed pressure is not enough for engine start

Question 30

When will the crossbreed valve automatically open?

Answer 30

- Only one side bleed source is available - Engine 2 start in the air - Engine 1 start in the air if APU is not available

Question 31

What are some things that will close the ECS packs?

Answer 31

- Any engine start if APU is the bleed source - Engine start on the ground - Respective bleed system duct leak - Bleed air source not available for the pack - TL set to MAX on takeoff - REF A/I set to ALL on takeoff - REF ECS set to OFF on MCDU (APU is OFF)

Question 32

When are ECS packs recovered?

Answer 32

- TL not at MAX, and - Airplane is 500 AFE with both engines operating - Airplane is > 9,700 MSL with one engine operating

Question 33

What happens if smoke is detected in the recirculation bay?

Answer 33

- Both record fans deactivate - Cargo record fan deactivates - Cargo outflow valve closes

Question 34

Where does the CPCS get cruise flight live & landing elevation from?

Answer 34

- FMS before takeoff or CPCS calculates using ambient pressure - LFE may be manually inputted

Question 35

What color is the LFE on the EICAS?

Answer 35

- Green FMS input | - Cyan Manual input (an M will be in front of LFE)

Question 36

What is the ABORT mode?

Answer 36

- Cabin is scheduled back to the takeoff altitude if - Airplane stop climbing and begins a descent, and - Airplane has not climbed > 5,000 AFE or > 10,000 MSL