Air conditioning and pressurization Flashcards
Which engine normally provides bleed air to which pack
The left engine - left pack
right engine - right pack
How is the bleed air from both engines kept separate?
The isolation valve
Can the left engine provide bleed air to the right pack? If so, how?
Yes. By selecting the ISOL switch to OPEN, the BLEED SOURCE rotary selector to L ENG, and then placing the BLEED VALVES rotary selector in MANUAL
How is the ISOL switch normally positioned?
CLSD
What does the cabin pressure controller do?
It independently acquires and monitors cabin pressure, outside air pressure, differential pressure and rate of change information and commands the outflow valves to move based on this information
How many automatic cabin pressure controllers are there and why?
2
One is active and the other is in standby ready to assume control if the active controller fails
What does the CPAM (Cabin Pressure Acquisition Module) do?
First, it acquires cabin pressure and rate of change information for display on the EICAS.
In the event both CPCs fail, this information will let the crew know how they should manually operate the outflow valve.
Second, it commands the passenger oxygen masks to deploy and the seatbelt no smoking signs to illuminate if the cabin altitude exceeds 14,000 feet
Describe how to manually control cabin pressure
Push the PRESS CONTROL switch light and adjust the MAN RATE knob to full decrease.
Then move the MAN ALT switch either up or down depending on if you want the cabin to climb or descend.
To increase the rate of change, slowly move the MAN RATE knob towards the increase position.
How many outflow valves are there
1
How is the outflow valve powered?
Electrically (Not pneumatically) by 3 separate electric motors
What commands the 3 outflow valve motors?
Motor 1 - CPC 1
Motor 2 - CPC 2
Motor 3 - Manually controlled by the pilot with the MAN RATE & MAN ALT knobs
During automatic mode when the CPCs are in control, how many operational phases are there?
7
Name the CPC’s operational phases
Ground phase Takeoff phase Flight abort phase Climb/cruise phase Descent phase Landing phase touch and go phase
What does the flight abort phase do?
It will assume the departure field elevation will be the landing field elevation until the airplane climbs through 6000 feet or 10 minutes passes
What is the EMER DEPRESS button used for?
In an emergency the crew can push it to depressurize the airplane. Its use is prohibited above 15000 feet
When will the cabin altitude aural warning sound?
At a differential pressure of 8.7
Will the cabin fully decompress while flying at 41,000 Feet?
No. The cabin will depressurize up to a cabin altitude of 14,500 feet plus or minus 500
What does the ground valve do?
It ensures the cabin is depressurized on the ground, and increases air flow for avionics cooling
When does the ground valve open and close?
The ground valve closes when the main cabin door is closed prior to departure, and opens after landing with weight of wheels
What does the OVBD COOL FAIL status message indicate?
The ground valve failed to open after landing
What does the “PACK” acronym stand for?
Pneumatic Air Conditioning Kit
Which Pack provides cooling to the cockpit? Which to the cabin?
Left - cockpit
Right - cabin
Can the left pack provide cooling to the cabin if the right pack fails?
Yes
How can the left pack provide cooling to the cabin if the right pack fails?
Both packs provide air to the mixing manifold under the aft cargo.
Internal baffling in the mixing chamber will allow either pack’s air to both the cockpit and cabin.
