Air conditioning / Pressurisation Flashcards
setting the bleed selector knob to norm or max allows what to happen to the bleed port selections?
system to alternate between hi and low stage bleed as reqd
Allows ECU to modulate the Nacelle FCSOV’s (Flow Control Shutoff Valve) to control the volume of air from both engines at increased levels.
Changes rated power from NTOP to MCL
what % of airflow does cabin recieve
75%
Cabin outlet temp range
15-27 deg c
Damper valve moves up for heat or cool
Full up for cooling
CABIN PACK HOT or FLT COMPT PACK HOT caution light means? What automatically happens?
Respective pack becomes too hot. Causes turbine shutoff valve to close turning off pack. Once condition is rectified, light extinguishes.
CABIN DUCT HOT or FLT COMPT DUCT HOT caution light means? What automatically happens?
Respective Duct becomes too hot. Causes the affected turbine shutoff valve to close, turning off pack. Once the condition is rectified, the light extinguishes
Can A/C be flown unpressurised?
Yes, Ram air in fin is intake, outflow valve is exhaust
Which Avionics cooling fan can be operated on battery power? Redundancy?
Fan 1 on battery, fan 2 if fan 1 fails
FANS FAIL Alert means
Two avionics cooling fans have failed
AVIONICS caution and FANS FAIL message on ED means what?
Two avionics cooling fans have failed, displayed on ground only.
An avionics related no dispatch condition is sensed when the aircraft is on the ground
Will avionics cooling fans operate at cockpit temp below 5 degC
No
How is the aft outflow valve operated? From what bus?
Electrically operated by the LEFT MAIN DC BUS
True or false, the forward and aft safety valves operate as positive and negative pressure relief valves?
True
What are the 4 modes of pressurisation?
Auto
Manual
Emergency smoke removal
Pressure dump
Depressurising on ground conditions? Outflow valve to open.
Engine PLA <60%
& WoW both gear
When is the Aft safety valve held open? What holds it open?
APU operating (or) at least 1 engine running at idle (and)
On ground with power levers at flt idle or low power settings.
Cabin Pressurisation Controller CPC
What cabin altitude does the outflow valve pre-pressurise the cabin to at take off
-400’ AGL
How long does the pressurisation controller remain in take off mode for?
10 mins in case of a return to field
When does the pressurisation flight sequence begin
When the take off sequence is completed
The descent sequence in auto mode can be increased to the rate of descent sequence how?
A high rate of descent
When moving the main diff valve to DECR what happens?
Aft Outflow valve opens further decreasing the cabin pressure and increasing the cabin altitude
Do you need electrical power to operate the FWD OUTFLOW knob
No
True or False, The FWD OUTFLOW VALVE and AFT OUTFLOW VALVE work together to maintain the A/C’s pressurisation
False, theyre independent of each other
What settings are available for the FWD SAFETY VALVE when selected by the Forward safety Valve selector guarded switch.
Full open
Full Closed
Can only be selected in between using the rotary knob in the pressurisation panel
What procedure can the FWD SAFETY VALVE be used in? and how?
Removing smoke from flight deck. By opening valve and closing the AFT OUTFLOW FALVE (in auto mode) to suck it out the front of the A/C
What does selecting the dump mode do?
Fully opens the outflow valve to dump cabin pressure
Can also be used for smoke evacuation
When the Cabin pressure controller is operating in the auto mode, what is the normal position of the FWD OUTFLOW rotary knob?
Fully CLSD
What does the MAN DIFF spring loaded switch do?
In manual mode, moves the outflow valve to increase or decrease cabin pressure
What does the FAULT light mean on the PRESSURISATION CONTROL PANEL
Fault has been detected in the Cabin Pressure control system
Take off with bleed on is permitted under what supplemental procedure in the AFM. What limitations are associated with restriction
Tailwind < 10kts RWY slope < 2* Taking off with MTOP and UPTRIM Operations with LDG GEAR extended N/A Operations with one bleed system into N/A
During the smoke removal procedure when opening the fwd safety valve using the rotary knob in the normal auto mode, what happens to the aft outflow valve
Begins closing to maintain the current cabin altitude. This leads to a vacuum in the front of the aircraft removing smoke on the flight deck.
When the fwd outflow selector is turned clockwise for smoke removal in the Auto pressurisation mode, what does the rear outflow valve do?
Closes to maintain desired cabin pressure. Allowing smoke to vacate through the fwd pressurisation bulkhead and still maintain cabin altitude
What cabin Alt will CABIN PRES warning light illuminate?
9800’
What happens if both digital channels of the ECU (Electronic Control Unit) fail
The Pack FCSOV will close and the aircraft will depressurise
The ECU keeps the temperature in the supply ducts between ____ & ____*
2.8 & 71*C
Auto Vs Manual Pack operation?
Auto: ECU regulates temperature in the cabin by determining what the duct temperature is.
Manual: System targets the duct temperature instead of a cabin temp
Auto Vs Manual Pack operation?
Auto: ECU regulates temperature in the cabin by determining what the duct temperature is.
Manual: System targets the duct temperature instead of a cabin temp
How long should you wait until a change in gasper outlet temp can be felt?
1-3minutes
How long should you wait until a change in gasper outlet temp can be felt?
1-3minutes
Manual mode duct temperature limits?
3-71*C
What is the layout of the air condtitioning system and where is it located?
Uses two ACM’s (air cycle machines) that utilise a single primary and secondary heat exchanger.
They are located in the aft fuselage.
Why do the air cycle machines (ACM’s) utilise common heat exchangers?
Provides redundancy of two packs while allowing access to a much larger dual heat exchanger during operation with a single ACM.
What does the Bleed control selector MIN / NORM / MAX actually change?
Modulates the Nacelle shut off valves
MIN - for minimum bleed air flow
NORM - for moderate bleed air flow
MAX - for maximum bleed air flow
Is APU bleed airflow controlled by the bleed flow selection knob?
No it is controlled by a flow schedule internal to the ECU (environmental control unit)
In addition to the flight compartment, the flight compartment pack also supplies conditioned air to?
Rear baggage compartment
Forward cabin attendant gasper
Lavatory gasper
In addition to the flight compartment, the flight compartment pack also supplies conditioned air to?
Rear baggage compartment
Forward cabin attendant gasper
Lavatory gasper
What condition indicates a failure of both digital channels? What will happen?
A combination failure ie.
- #1 & #2 Bleed Hot
- Cabin Pack / Duct Hot & Flt Comp Pack / Duct Hot
Aircraft will depressurise
