Air Con / Vent / Press Flashcards by Robin Cross

How is cabin temperature controlled and by which valves?

Zone controller + two pack controllers

Trim air valves and hot air (press reg) valve

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

±2.5ºC

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What is the pack controlled by, if installed?

Four stages of the air cycle unit?

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

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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?

Outlet of turbine at end of air cycle system

Compressor outlet reading after compressor but before main heat exchanger

Pack control valve

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

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

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What happens to outflow valve when Ram Air pressed?

Why might ram inlet not open?

Where does Ram air go?

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

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What is mixed in the mixer unit?

How is the mixer unit air warmed?

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.

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

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

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

ACSC 1 for cockpit
ACSC 2 for cabin

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

When do the ram inlets (pack) close automatically?

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

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

Single pack operations
APU bleed on

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

If APU bleed being used?

ACSC to EIU
ACSC to APU ECB

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

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

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

How is temperature and flow then controlled?

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)

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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?

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.

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How many cabin fans are there?

Two
Both selected ON or OFF via single CAB FANS pb

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Which are the four modes of the pressurisation system?

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

*Depressurisation
after LDG, gradual release of any overpressure

Which valves does the DITCHING pb close?

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 ***

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?

ADIRS
FMGC
EIU
LGCIU

Signals to ECAM

Yes- cross channel link

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

Backup of CPC 1

Two safety valves- overpressure and underpressure threshold values?

Where are they located?

Overpressure 8.6 PSI
Underpressure -1 PSI

Rear pressure bulkhead, above flotation line

Under what conditions will the RPCU open the outflow valve?

Residual Pressure Control Unit

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

When do the CPCs switch?

70 sec after each landing
Ico: CPC failure

CPC max cabin altitude?
Max TO/LDG alt?

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

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

What are the six pressurisation schedule modes?

**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

What is max ΔP in automatic mode? Does cabin alt level off when aircraft enters intermediate level off?

8.06 PSI Levels off in climb but not in descent

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?

Cuts power to the AUTO motors 5 sec delay to outflow valve indication on ECAM Outflow valve will not automatically open after landing : monitor

When will the CABIN VS flash on PRESS page? When will it flash on DOOR/OXY page?

**PRESS** 1750 fpm (stops below 1650 fpm) **DOOR/OXY** 1800 fpm for 5.5 sec (stops below 1600 fpm)

When does ΔP flash? When will it turn amber?

1.5 PSI in flight phase 7 (800 ft to LDG) (stops at 1 PSI) Amber outside -0.4 PSI to 8.5 PSI

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

8800 ft (stops at 8600 ft) 9550 ft

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

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)

Outflow valve- why amber?

If more than 95% open in flight

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

Over 40ºC Under 35ºC

When is Open Circuit Config (vent) used?

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

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

On the ground: under 40ºC duct temp In flight: Normal config- when skin temp max 35ºC (32ºC if decreasing)

When is Intermediate Config used? What is different to Closed Config?

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

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

BLOWER OVRD- Blower stops, Closed circuit, simple loop, air con added EXTRACT OVRD- both fans run

What indications given if smoke detected in Avionics bay? What is Smoke Config? How is it activated? What happens ico: Controller Failure?

**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

How are the batteries ventilated? How are the Lavs / Galley ventilated?

**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.

**Limitations** Limit for normal config avionics ventilation on the ground?

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

**Limitations** Min / max ΔP Safety valve ΔP

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