U21P201 Pressurization

The pressurization system on the A320 normally operates automatically to adjust the cabin altitude and rate of change of altitude to ensure maimum passenger comfort and safety!

The pressurization system on the A320 normally operates automatically to adjust the cabin altitude and rate of change of altitude to ensure maimum passenger comfort and safety!

The pressurized areas are" • the coc#pit • the a$ionics bay • the cabin • and the cargo compartments!

The Pressurized Areas

Pack 1

Pack 2

The concept of the system is simple! Air is supplied from the Air %onditioning &ac#s to the pressurized areas!

Outflow Valve

The Pressurized Areas

Pack 1

Pack 2

An 'utflo( $al$e is used to regulate the amount of air allo(ed to escape from the pressurized pressurized areas! areas!

Cabin Pressure Controllers

%&% )

Electric  Motor 

Pack 1

%&% 2

Electric  Motor 

Pack 2

Automatic control of the outflo( $al$e is pro$ided by t(o %abin &ressure %ontrollers! Each controller has an electric motor to mo$e the outflo( $al$e!

Pack 1

%&% )

%&% 2

! 1

! 2

Pack 2

A controller* motor combination is #no(n as a system ! 'nly one system (ill operate at any one time (ith the other system acting as bac#up!

Manuall" Controlled Motor 

MA#

Pack 1

Pack 2

A third motor is installed for use in the e$ent of both automatic systems failing and re+uires a manual input to open or close the outflo( $al$e!

afet" Valves

! 1

Pack 1

Pack 2

To a$oid ecessi$e cabin differential pressure safety $al$es are installed!

Cabin  $ifferential Pressure

! 1

Pack 1

Pack 2 ,et us loo# at the operation of the outflo( $al$e for an aircraft in cruise and (hat happens to cabin differential pressure- cabin altitude- and %abin .ertical speed! /e (ill start (ith %abin ifferential &ressure! 1f the outflo( $al$e is closed- or only allo(ing a small amount of air to escape- then the cabin differential pressure (ill increase!

Cabin Altitude

! 1

Pack 1

Pack 2

No( lets loo# at (hat happens to %abin Altitude ! 1f the outflo( $al$e is closed- or only allo(ing a small amount of air to escape- then the %abin Altitude (ill descend!

Cabin Vertical %eed

Cabin Altitude

! 1

Pack 1

Pack 2

/e can also see (hat the cabin is doing by reference to $ertical speed! /hen the outflo( $al$e closes closes the cabin altitude (ill decrease (ith a .ertical .ertical peed! peed!

Cabin  $ifferential Pressure

Cabin Vertical %eed

Cabin Altitude

! 1

Pack 1

Pack 2

1f the outflo( $al$e is fully open- a lot of air is allo(ed to escape- the cabin pressure (ill decrease- the cabin altitude (ill climb (ith a .ertical peed!

! 1

Pack 1

Pack 2

The cre( can monitor all cabin pressure functions on the E%AM %A4 %A4 &5E &5E &age!

,ets loo# at the information- associated (ith the pressurization system- that is presented on the %A4 &5E page! The pac# indication is displayed green (hen the associated pac# is on!

The 'utflo( $al$e position can be monitored- and the system controller in use is sho(n!

There is a single indication for the safety $al$es! /e (ill loo# at ho( this indication changes in the Abnormal operation module!

The %abin ifferential &ressure- or elta &- sho(s the difference- in &1- bet(een the cabin pressure and eternal pressure! This differential pressure (ill be at zero on the ground and increase as the aircraft climbs!

The %abin .ertical peed sho(s the rate of change- in 6t*Min- of cabin altitude! 6or passenger comfort the pressurization system (ill aim to #eep this rate of change as small as as possible! possible!

The %abin Altitude is also sho(n!

The .ent- 1nlet and Etract indications are associated (ith the A$ionics .entilation ystem and (ill be discussed in a separate module!

ECAM CRUISE Page

'n the E%AM %ruise &age there are indications of" • %abin ifferential pressure • %abin $ertical speed • %abin altitude

ECAM DOOR/OXY Page

There is also an indication of cabin $ertical speed on the E%AM oor page! Note that this indication indication is is only displayed (hen the aircraft is airborne!

'n the o$erhead panel there is a %A41N &5E panel containing controls to operate the &ressurization system! Under normal conditions no pilot action action is is re+uired on this panel during flight!

The &ressurization M'E elect s(itch has t(o settings7 Automatic and Manual!

The normal position for this s(itch is- lights out! 1n this position the pressurization system is in Automatic mode!

MA#

The use of Manual Mode and the Manual .ertical peed control (ill be discussed in the abnormal operation module!

The ,anding Ele$ation selector normally remains in the Auto position! ,anding ele$ation- (hich is re+uired by the &ressurization system- is then pro$ided by the 6M8 based upon ele$ation of the destination airport! 1f the landing ele$ation is not a$ailable from the 6M8- then it can be set manually using this selector! 9ou (ill use this selector in the abnormal operation modules!

The guarded itching s(itch is pro$ided to close all $al$es belo( the (aterline so that the aircraft can be sealed in the unli#ely e$ent of a ditching!

 Module completed