Air Con / Vent / Press

Question 1

How is cabin temperature controlled and by which valves?

Answer 1

Zone controller + two pack controllers

Trim air valves and hot air (press reg) valve

Question 2

How much can the temperature be varied by on the FAP?

Answer 2

±2.5ºC

Question 3

What is the pack controlled by, if installed?

Four stages of the air cycle unit?

Answer 3

ACSC Air Con Sys Controller

• Enters pack flow valve then primary heat exchanger
• Goes through compressor gaining temp and pressure
• Back through Main heat exchanger to cool
• Expands in turbine, driving it, and becoming very cold
  water separator dries the air before entering the turbine

Question 4

Where is the outlet temp taken from? (top reading on SD, over C-H gauge)

Where is the compressor outlet temp taken from? (lower reading, over LO HI gauge)

What do the pressure and valve position data pertain to?

Answer 4

Outlet of turbine at end of air cycle system

Compressor outlet reading after compressor but before main heat exchanger

Pack control valve

Question 5

Pack Control Valve
What drives and controls it?
When will it spring shut?
When will it automatically shut?

Answer 5

Pneumatic drive, electric control
from pack controllers or ACSC

Springs shut when no pressure

Automatically shuts:
* Overheat on ground
* Engine start
* Fire pb
* Ditching pb

Question 6

What happens to outflow valve when Ram Air pressed?

Why might ram inlet not open?

Where does Ram air go?

Answer 6

Outflow valve to 50% unless ΔP over 1 PSI or in manual control

Check valve to ram inlet is locked over 1 PSI ΔP

Mixing unit

Question 7

What is mixed in the mixer unit?

How is the mixer unit air warmed?

Answer 7

Cold air from packs and cabin air from recirculating fans

LP external air or ram air can also be used

Hot air (from PCV but bypasses the pack) can be added downstream of mixing unit via the trim valves into each cabin section.

Question 8

What operates the hot air valve? Which computer?
Why would it spring shut?
Why would it automatically shut?

Answer 8

Pneumatic, electric control via HOT

AIR pb and ACSC1

Springs shut if no pressure

Automatically shuts:
* Both lanes of ACSC1 or 2 fail
* Duct overheats
* Two trim air valves fail

Question 9

Which trim air valves are operated by ACSC 1 / 2 ?

Answer 9

ACSC 1 for cockpit
ACSC 2 for cabin

Question 10

ACSCs control their own pack, how is temperature regulated and flow?

When do the ram inlets (pack) close automatically?

Answer 10

Ram inlets and bypass for temp
Pack flow valve for flow

TO- TOGA + MLG on ground
LDG- MLG on ground + >70kt
reopens 20 sec after decel through 70

Question 11

Pack flow affects the pack flow valve, under what two circumstances will it always provide HI?

Answer 11

Single pack operations
APU bleed on

Question 12

Idle can be increased if cooling demand not met- via which computers?

If APU bleed being used?

Answer 12

ACSC to EIU
ACSC to APU ECB

Question 13

If an ACSC lane fails, the other takes over. What happens if both fail?

Answer 13

Associated pack lost
Hot air valve closes
Trim valves freeze in last position

Question 14

If a pack fails, it can operate in a reduced mode, how does this work?

How is temperature and flow then controlled?

Answer 14

Heat exchanger cooling mode:

Passes through primary heat exchanger and then majority of flow is bled before entry into compressor.

Remaining flow passes through the jammed compressor / turbine.

Flow is automatically reduced, but flow and temperature remain controlled as normal via ram inlets and bypass (temp) and pack flow valve (flow)

Question 15

Hot air (pressure regulating) valve failure:

There is no effect if it fails open, what if it fails closed?

What if the trim valves fail?

Answer 15

Optimised regulation is lost

Trim air valves all close
Pack 1 controls cockpit temp
Pack 2 controls cabin temp
uses average of FWD/AFT temp settings

Trim valve failure- optimised temp regulation lost for corresponding zone.

Question 16

How many cabin fans are there?

Answer 16

Two
Both selected ON or OFF via single CAB FANS pb

Question 17

Which are the four modes of the pressurisation system?

Answer 17

• Ground
  outflow valve fully open
• Prepressurisation
  avoid surge on rotation
• Pressurisation in flight

*Depressurisation
after LDG, gradual release of any overpressure

Question 18

Which valves does the DITCHING pb close?

Answer 18

Any valve below the flotation line (which includes Outflow Valve)

• Outflow valve
• Ram air inlet
• Avionics Inlet / Extract
• Pack Flow Control Valves
• FWD cargo outlet isol valve ***

Question 19

Which four other computers do the CPCs receive data from? To which other computer does it send signals?

Can the CPCs communicate with each other?

Answer 19

ADIRS
FMGC
EIU
LGCIU

Signals to ECAM

Yes- cross channel link

Question 20

Each CPC has a backup section with an independent power supply for manual mode. Which one sends an outflow position signal to ECAM

Answer 20

Backup of CPC 1

Question 21

Two safety valves- overpressure and underpressure threshold values?

Where are they located?

Answer 21

Overpressure 8.6 PSI
Underpressure -1 PSI

Rear pressure bulkhead, above flotation line

Question 22

Under what conditions will the RPCU open the outflow valve?

Residual Pressure Control Unit

Answer 22

If
* not fully open
* CPCs both failed or in manual
* On ground
* Engines OFF or ADIRS < 100kt

Question 23

When do the CPCs switch?

Answer 23

70 sec after each landing
Ico: CPC failure

Question 24

CPC max cabin altitude?
Max TO/LDG alt?

Where does it obtain landing elevation, QNH and pressure altitude from?

Answer 24

8000 ft cabin alt
14100 ft TO/LDG elev

LDG ELEV and QNH from FMGC
Press Alt from ADIRS

if FMGC fails, takes baro information from ADIRS and manual LAND ELEV from panel

Question 25

What are the six pressurisation schedule modes?

Answer 25

GN
Before TO / 55s after landing
Outflow valve fully open
Residual pressure releases 500 fpm

TO
Prepressurised @ 400 fpm to -0.1 PSI

CL
Follows fixed law

CR
Maintains cab alt at level off OR land elev- max of 8000

DE
Target landing pressure: elev + 0.1 PSI, max RoD 750 fpm

AB
If no climb after TO, stops cabin alt climb- resets to TO elev + 0.1

Question 26

What is max ΔP in automatic mode?

Does cabin alt level off when aircraft enters intermediate level off?

Answer 26

8.06 PSI

Levels off in climb but not in descent

Question 27

In manual mode, what does the MODE SEL: MAN pb do?

Why should you be slow with the MAN V/S CTL selector?

What threat is there after landing in manual mode?

Answer 27

Cuts power to the AUTO motors

5 sec delay to outflow valve indication on ECAM

Outflow valve will not automatically open after landing : monitor

Question 28

When will the CABIN VS flash on PRESS page?

When will it flash on DOOR/OXY page?

Answer 28

PRESS
1750 fpm (stops below 1650 fpm)

DOOR/OXY
1800 fpm for 5.5 sec (stops below 1600 fpm)

Question 29

When does ΔP flash?
When will it turn amber?

Answer 29

1.5 PSI in flight phase 7 (800 ft to LDG)
(stops at 1 PSI)

Amber outside -0.4 PSI to 8.5 PSI

Question 30

When will CABIN ALT indication flash?
When will it display in red?

Answer 30

8800 ft
(stops at 8600 ft)

9550 ft

Question 31

When will the safety valve icon display in amber?
When do they open?

Answer 31

Whenever either valve is open
Opens at 8.6 PSI or -1PSI

(Also says 8.9 to 9.7 PSI - range due to innacurate ΔP in MAN mode)

Question 32

Outflow valve- why amber?

Answer 32

If more than 95% open in flight

Question 33

When does the FSC / Fan speed controller switch the two fans to high? And back to low?

Answer 33

Over 40ºC
Under 35ºC

Question 34

When is Open Circuit Config (vent) used?

Answer 34

On the ground only (throttle NOT TO)
When duct temp over 40ºC

Question 35

When is Closed Config used on the ground? In flight?

Answer 35

On the ground: under 40ºC duct temp

In flight: Normal config- when skin temp max 35ºC (32ºC if decreasing)

Question 36

When is Intermediate Config used?

What is different to Closed Config?

Answer 36

In flight only

Skin temp over 35ºC (32ºC when decreasing)
Or if skin temp outside measurement range -50 to 80ºC

Difference- Skin Air Outlet partially open

Question 37

What happens when you turn the BLOWER to OVRD for less noise in the cockpit?

What happens if EXTRACT is in OVRD?

Answer 37

BLOWER OVRD-
Blower stops, Closed circuit, simple loop, air con added

EXTRACT OVRD- both fans run

Question 38

What indications given if smoke detected in Avionics bay?

What is Smoke Config? How is it activated?

What happens ico: Controller Failure?

Answer 38

Smoke Config
BLOWER + EXTRACT FAULT
Push both for OVRD

Air con supplies cooling air, vented overboard (Skin Outlet partly open)

Skin Inlet, Avionics Inlet, Skin Exchange Isol - all closed

Controller Failure
BLOWER + EXTRACT FAULT
Push both for OVRD

Same as Smoke config except:
Skin Inlet + Oulet, Skin Exchange Isol - stay in last position

Question 39

How are the batteries ventilated?

How are the Lavs / Galley ventilated?

Answer 39

Batteries
Venturi in aircraft skin sucks air from around batteries and vents overboard

Lav/Galley
Extraction fan next to outflow valve draws air from these areas. Temperature sensors in ducting.

Question 40

Limitations
Limit for normal config avionics ventilation on the ground?

Answer 40

49ºC or below - none
up to 55ºC - 2 hour
up to 60ºC - 1 hour
up to 64ºC - 30 min

Question 41

Limitations
Min / max ΔP
Safety valve ΔP

Answer 41

Maximum ΔP: 9 to -1 PSI
* Safety valve 8.6 PSI
Table in FCOM LIM for cabin alt : pressure alt