Chapter 2: AMS

Question 1

Components of Pressurization System

Answer 1

• CPC
• OFV (behind FWD Cargo)
• NPRV (aft bulkhead, -0.5psi)
• PPRV “safety valve” (aft bulkhead, connected to static port, 8.6psi)
• Static Port

Question 2

Cabin Nominal Differential Pressure

Answer 2

Up to 37,000 MSL: <= 7.8 psi

Above 37,000 MSL: <= 8.4 psi

Question 3

“Cabin Diff Press Fail” EICAS

Answer 3

Pressure Differential > 8.5 psi or < -0.3 psi

Question 4

DUMP Button

Answer 4

Both Packs off; Both Recirc Fans off; (if auto mode) modulates OFV to maintain 2,000 fpm to 12,400’ cabin altitude, then closes OFV to allow cabin altitude to rise by natural leak.

Question 5

“Cabin Altitude Hi” EICAS

Answer 5

Cabin Altitude > 9,700’

Or > LFE + 500’ (if LFE > 9,400’)

Question 6

CPCS “Abort” Mode

Answer 6

If, after takeoff, climb stopped and a decent is immediately initiated while below 10,000’ MSL or 5,000’ AGL.
Cabin altitude is scheduled back to T/O altitude.

Question 7

AMS Controller Functions

Answer 7

• Bleed Control
• Air Conditioning Control
• Hot Air Leak Detection
• Crew O2 Monitoring
• Wing/Engine Ice Protection

Question 8

Pneumatics Overheat Detection

Answer 8

• Engine Bleeds
• Air Conditioning Ducts
• APU Bleed
• Anti Ice
• Trim Air (if applicable)
• 2 Loops, both must detect leak

Question 9

Engine Bleed Valve Logic

Answer 9

Automatically closed when:

• Overheat
• Leak
• Bleed Unavailable
• Engine Fire Detected
• Associated Fire Handle Pulled
• If only associated Pack is off and other bleed is available (X-Bleed opens), no EICAS
• Bleed 1 only: X-Bleed fails open and Bleed 2 is available

Question 10

X-Bleed Valve Logic

Answer 10

Automatically closes when:

• Fire handle pulled
• Leak Detected
• One side greater than 90 psi

Question 11

Recirculation Fans Logic

Answer 11

Automatically commanded off when:

• Both packs are off
• DUMP button pressed
• Cargo fire
• Smoke in recirculation bay
• Recirc. 1 only: On ground, Pack 1 off, Pack 2 on; in-flight, Pack 1 off, KIAS > 50

Question 12

Packs Logic

Answer 12

The associated FCV (flow control valve) is commanded closed when:

• Any engine start on ground
• Any engine start with APU
• Associated engine start in-flight
• Bleed source unavailable
• Associated bleed leak
• Associated pack fail
• Pack 1 only: Ram Air BIT
• Commanded by FADEC

Question 13

FADEC Pack Off Logic

Answer 13

FADEC sends ECS OFF signal to the AMS when:

• Takeoff or Go-Around, one engine inoperative, APU unavailable
• Takeoff or Go-Around, thrust levers set to MAX, and APU unavailable
• Takeoff, REF ECS OFF, and APU unavailable
• Takeoff, REF ECS OFF, REF A/I ALL
• Go-Around, thrust levers set to MAX, Wing A/I requested

Question 14

Flight Deck Emergency Ram Air Ventilation Valve

Answer 14

Both packs off, altitude < 25,000’
Operates via check valve
Can assist with pressurization or smoke removal