Air conditioning - Press - Vent Flashcards
What compose the air conditioning system ?
- two pack control valves
- two packs
- one mixing unit
What is the purpose of the mixing unit ?
mix air from the cabin and the air coming from the packs
What is the purpose of the trim air valve and the hot air ?
optimize the temperature by adding hot air tapped upstream of the packs
What is the purpose of the pack flow control valve ?
It is controlled by the ACSC and regulate the air flow
When will the pack flow control valve close ?
- pack overheat
- low pressure
- fire PB
- engine start
What is the purpose of the emergency RAM air ?
provide ambient air to the mixing unit.
Can be use to remove smoke and in case of dual pack failure
When will the emergency ram air inlet open ?
- when PB pressed and
- delta P is less than 1PSI and
- Outflow valve in automatic control mode (will open at 50%)
How does the ACSC control the temperature of the pack ?
It adjust the temp by modulating bypass valve and the ram air inlet flap.
When will the pack flow automatically adjust ?
- single pack
- use of APU bleed
- normal flow if in LO and temp cannot be satisfied
What compose the ACSC ? and how will it work in case of failures ?
Composed of two lanes per ACSC
Single lane failure => no effect the other takes over
Both lanes failure => pack lost, hot air valve close and associated trim air valve close
What compose the cabin press system ?
- two CPC
- one residual pressure control unit
- one outflow valve with an actuator with 3 motors
- one control panel
- two safety valves
In normal cabin press operation what control the system ?
Only one CPC at a time, the other is on standby
When will the transfer between CPC happen ?
failure
70sec after landing
Can be forced by selecting Mode sel to MAN for 10sec or more and back to auto
What is the normal cabin pressure limit ?
8000ft
How is the outflow valve operated and by what ?
3 differents motors
- two for automatic mode associated with their CPC
- one for manual mode
In manual mode the N°1 CPC backup section signal the position to ECAM
How many safety valves ? when will they activate ?
too high above 8,6PSI
too low -1PSI
Avionic vent, what are the normal configurations ?
- open circuit config
- closed circuit config
- intermediate config
Avionic vent, In the open circuit config how is the avionic cooled ?
by ambiant air, the skin heat exchanger is not used (closed)
Avionic vent, in the closed circuit config how is the avionic cooled ?
skin air inlet and outlet closed, cooled by skin heat exchanger
Avionic vent, when can the open circuit be used ?
what about the closed ?
on the ground only
for the closed can be used:
- ground when takeoff power or below ground threshold
- in flight when BELOW in flight threshold (around 33°c)
Avionic vent, what is the intermediate configuration ? and when can it be used ?
Same as the closed config but some of the air is extract overboard via a partially open skin air outlet valve.
In flight when skin temp is ABOVE inflight threshold (around 35°C)
Avionic vent, what is the smoke configuration ?
blower and extract are set to override, the air conditioning is supplying cooling air which is then exhausted overboard via a partially open skin air outlet valve.
The skin heat exchanger is not used
In case of the loss of both FMGC how does the Press system obtain the landing elevation ?
Manually selected via the rotary selector
With the loss of CPC 1+ 2 how is the cabin altitude controlled ?
Mode sel MAN and use toggle to adjust cabin alt.
Two ways to manage this failure:
- Manually select a cabin VS of 300ft/min and 0 when leveling off or
- Keep current cabin alt and once at this cabin altitude fully open outflow valve => Once fully depressurized monitor closely the rate of descent of AC has it will impact directly the rate of descent of the cabin alt.
When in MAN mode for the cabin alt, what happen to the outflow valve when the toggle is selected up ?
open the outflow valve => Makes the cabin alt climb
On takeoff why does the press system slightly pressurise the cabin ?
to avoid a surge on takeoff
Avionic vent, What is the effect of pressing Blower to overide, Extract to overide, what will cool the A/C and which config does the system goes into ?
Blower overide => Stop running
Extract overide => Keep running
A/C is cooled by air from the air conditioning
The system goes into the closed config
