DSC 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, this 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.
