Pressurization Flashcards
True or False: The aircraft’s pressurization is provided by engine bleed air?
True
Which valve is primarily manipulated to control the pressurization in the cabin of the aircraft?
Aft Outflow Valve
How many safety valves are there in addition to the Outflow Valve?
2
Forward Safety Outflow Valve
Aft Safety Outflow Valve
How many different modes are there on the pressurization system?
4 Modes of Pressurization
- Automatic Mode
- Manual Mode
- Emergency (Smoke Removal) Mode
- Pressure Dump Mode
Manual mode is used on the pressurization system for what reason?
What does it do?
Short Answer: Auto Mode Inoperative
Selecting MAN turns off the Cabin Pressure Controller and enables manual control of the cabin differential pressure via the Aft Outflow valve by using the MAN DIFF(Manual Differential) switch located directly below the mode select switch.
Holding the spring-loaded toggle switch to the DECR side accomplishes what?
Opens the aft outflow valve as long as the switch is held. This decreases cabin pressure by increasing cabin altitude.
Holding the spring-loaded toggle switch on the pressurization panel to the INCR side accomplishes what?
Closes the aft outflow valve, increasing cabin pressure and decreasing cabin altitude.
If the aft outflow valve becomes inoperative, pressurization can be controlled by what?
The forward safety valve.
Forward Control Valve, it’s use is completely independent of the Aft Control Valve.
In normal operations it is situated completely counter clockwise
Lifting the safety guard and rotating the selector knob to the OPEN position allows the _____ to be fully open during emergency operations?
Forward Safety Valve
When the pressurization system is in AUTO and the FWD outflow valve is rotated to the OPEN position, it causes the AFT outflow valve to _____.
Close
Which pressurization mode would be used to depressurize the aircraft most rapidly?
DUMP Mode
True or False: When the pressurization system is set to DUMP, the aircraft can still be pressurized.
False
If bleed air is unavailable in flight, the cabin and flight compartments can be ventilated with what?
Outside Ram Air.
Turning the packs off the air entering through the dorsal fin NACA vents is routed to the cabin air supply duct. The ram air ventilates the cabin and flight deck and then exhausts through the Forward Safety Outflow valve.
The ram air vents used in flight when bleed air is not available are located on which part of the aircraft?
The Dorsal Fin NACA vents.
What is the maximum pressure differential pressure permitted by the cabin pressure controller?
5.46
At 25,000 feet, what cabin altitude gives you 5.46 PSI pressure differential?
8,000’
At what altitude does the cabin press warning light illuminate?
9,800 feet.
During automatic pre-pressurization, the cabin is pressurized how many feet below takeoff field elevation?
400’ Below
The cabin pressure controller is in the takeoff mode for no longer than how many minutes after takeoff?
10 minutes
Selecting the DUMP position on the pressurization system accomplishes what?
Fully Opens Aft Outflow valve.
When the pressurization mode switch is selected to the MAN position, which of the following is true?
Selecting INCR on the MAN DIFF switch closes the aft outflow valve,
True or False: The MAN DIFF switch on the pressurization panel should be used in both auto and manual modes of pressurization.
False
What is the Aft Outflow Valve?
The Aft Outflow valve is an electrically controlled valve located on the aft pressure dome. It is regulated by the Cabin Pressure Controller (computer) in response to Pressurization Control panel inputs (located on the flight deck overhead panel). It is the primary valve used for control of pressurization. The Aft Outflow valve is used for both Automatic and Manual pressurization control. It can also be used to dump cabin pressurization.
What is the Aft Safety Outflow Valve?
The Aft Safety Outflow valve is an electro-pneumatic valve and is also located on the aft pressure dome. The Aft Safety Outflow valve supplies additional venting during ground operation. The Aft Safety Outflow valve opens on the ground when at least one engine is running at idle, or when the APU is operating to supply additional bleed air venting.
What is the Forward Safety Outflow Valve?
The Forward Safety Outflow valve is a pneumatic valve located on the forward pressure bulkhead. The Forward Safety Outflow valve is for emergency operations (e.g. smoke removal from the flight deck). Both the Aft Safety Outflow valve and the Forward Safety Outflow valve incorporate positive and negative pressure relief valves.
True or False: The air conditioning packs cool the hot bleed air prior to it entering the flight compartment and passemger cabin.
True
