Operate Air Management System

Question 1

Recite Maximum and minimum pressure differential limitations

Answer 1

MAX Differential Pressure: 8.4 psi
MAX Differential Overpressure: 8.8 psi
MAX Differential Negative Pressure: -0.5 psi
MAX Differential Pressure for T/O and Landing: 0.2 psi

Question 2

What happens when the dump button is pressed while the mode selector is in AUTO? What about LFE CTRL? MAN?

Answer 2

Dump Function. This function is used in the event of:
Emergency evacuation, smoke evacuation, and fast cabin depressurization.
It turns off the recirculation fans and packs and controls the outflow valve to maintain the cabin altitude of climb at 2000 ft./min up to 12400 ft. (Not available in manual mode)

Dump Button:
Momentary pushbutton (does not stay pressed in)
When pressed, provides rapid cabin decompressurization by:
1. Opening the OFV (Outflow Valve) to command a 2000 FPM climb to 12,400 ft cabin altitude. At 12,400 ft cabin altitude, the OFV closes
2. Commanding PACKs OFF
3. Commanding recirculation fans OFF
If the Dump button is pressed a 2nd time, the system returns to normal (dump sequence is stopped)

Landing Field Elevation (LFE) control Mode
Allows manual input of landing field elevation, although the pressurization system will remain in automatic mode.
When the MODE selector is set to LFE CTRL, this knob sets the LFE. Reference the EICAS to set LFE.
Note: When LFE CTRL is selected, the LFE displays in cyan with an M.
Options:
-Up: Increases LFE
-Stop: No change to LFE
-Down: Decreases LFE

Question 3

Recite limitations that relate to engine/APU bleed (altitude).

Answer 3

Start
Temperature
Min: -54C Max: ISA +35
Altitude: Min – Max: 30,000ft

Continuous Operation
Temperature
Min: -54C
Max Temperature: ISA + 35 (52C)
Max Altitude: 33,000ft
Max Electrical Generator Use: 33,000ft
Max Engine Start: 21,000ft
Max Bleed Use: 15,000ft

Question 4

Understand the QRC Memory items that relate to the Air Management System

Answer 4

Cabin Altitude HI
Oxygen Masks … Don, 100%
Crew Communication … Establish

Question 5

When/Why would I use the LFE CTRL on the pressurization panel?

Answer 5

Landing field elevation control:
If the LFE isn’t available from the FMS database the LFE CTRL knob will allow selection of the landing field elevation.
The remainder of the system still works automatically.

Question 6

What does the outflow valve do? The positive pressure relief valve? The negative pressure relief valve? Cabin Pressure controllers?

Answer 6

The Outflow valve modulates airflow from the pressurized cabin into surrounding environment. It can be modulated automatically or manually.

Positive Pressure Relief Valve (Safety Valve): The positive pressure relief valve is a spring loaded check valve that works without any electrical power, and is independent the CPCS. Its function is to protect the airplane’s structure against damage due to positive overpressure. In case of outflow valve failure, the positive pressure relief valve opens if the pressure differential between cabin and surrounding environment exceeds 8.6 psi.

Negative Pressure Relief Valve (NPRV): Spring loaded check valve that works without any electrical power, and is independent of the CPCS. Its function is to protect the airplane structure against damages due to a negative differential pressure. The negative pressure relief valve opens if differential pressure between cabin and surrounding environment exceeds -0.5psi

Cabin Pressure Controller (CPC). The basic function of the controller is to control cabin pressure by commanding the outflow valve to modulate airflow through the valve from the pressurized airplane volume to the surrounding environment.
The CPC has two fully independent automatic channels, which are alternated following each flight.
Both channels provide a manual function as a backup, enabling the crew to control cabin pressure by directly actuating the outflow valve (OFV) position.