Airconditioning, Pressurization, & Pneumatics Flashcards
Location of RECIRC fan
Behind AFT pressure bulkhead
When does the RECIRC fan operate at slow speed?
Initially selected on, during engine start, and during single ACM operations
Pack control switch AUTO
ECU’s digital channels control the operation of the Pack Flow Control & Shut off Valve (FCSOV) and the respective Pack Bypass Valve (in response to manual inputs) to automatically regulate cabin or flight compartment temperatures
Pack control switch MAN
ECU’s analog channels control on the Pack Bypass Valves (in response to manual inputs) to regulate cabin or flight compartment temperatures, FCSOV remains full open
Pack control switch OFF
ECU closes the FCSOV and the Turbine SOVs resulting in a shut down of both ACMs
Air distribution for dual ACM operation
Half of left ACM for flight compartment, half of left ACM and all of right ACM for cabin compartment
Air distribution for single ACM operation
approximately 70% air flow
Describe the aft outflow valve
Electrically controlled, located on aft pressure dome, primary valve regulated by Cabin Pressure Controller
Describe the aft safety outflow valve
electro-pneumatic valve, located on aft pressure dome, supplies additional vent on ground with at least one engine running at idle or APU is operating, incorporates positive and negative pressure relief valve
Describe the forward safety outflow valve
pneumatic valve, located on forward pressure bulkhead, used for emergency operations, incorporates positive and negative pressure relief valve
Four modes of operation for pressurization system
Automatic,
Manual,
Emergency/Smoke Removal,
Pressure Dump
Pressurization mode select switch AUTO
Cabin altitude is automatically controlled by Cabin Pressure Controller by modulating the aft outflow valve
Pressurization mode select switch MAN
Turns off Cabin Pressure Controller and enables manual control via aft outflow valve
Pressurization mode select switch DUMP
Fully opens aft outflow valve to dump cabin pressure
Manual differential control switch INCR
Increases cabin pressure differential by closing aft outflow valve
Manual differential control switch DECR
Decreases cabin pressure differential by opening aft outflow valve
Pressurization Fault Warning Advisory Light (amber)
Illuminates when the cabin pressure controller system detects a fault, also momentarily during initial power up self-test mode
When does the aircraft being to pressurize?
PLA greater than 60 degrees
Describe the “takeoff abort” feature.
CPC remains in takeoff mode for at most 10 minutes after lift off, avoids the requirement to reselect the landing altitude
Describe emergency ram-air ventilation.
during unpressurized fight aircraft can be ventilated with outside ram air via dorsal fin NACA vents exhausting through forward safety outflow valve, directed by abnormal checklist
Environmental Control Unit (ECU) location
Avionics equipment bay
Bleed Air System (BAS) air sources
APU
Engine - low-pressure compressor port, high-pressure compressor port (depending on power setting)
Describe the Environmental Control Unit (ECU).
serves as the interface for control panel inputs and the mechanical and electrical components of the BAS, has redundant (left and right) digital and analog channels
Describe the ECU digital channels.
Control the LP and HP bleed ports of their respective engines, monitor bleed protective sensors to maintain correct temperatures, pressures, flow rates, and positioning of various BAS valves
