Pressurization Flashcards
The pressurisation system consists of:
2 air supply cabin pressure controllers,
A remote pressure sensor,
2 positive pressure relief valves,
4 negative pressure relief valves, &
A forward & aft outflow valve
What do the ASCPCs do?
The air supply cabin pressure controllers (ASCPCs), send & receive data necessary to control the pressurisation system
Is the L or R ASCPC considered the master controller?
Left
If valid ASCPC cabin pressure is not available, ………………. uses cabin pressure from the remote pressure sensor
AIMS
Data to & from the PRESSURISATION panel is provided from which bus?
629
Can the outflow valves be manually operated?
Yes, from the pressurisation panel
2 ……………. are used to regulate cabin pressure
(2) Outflow valves
Normally……….% of the air is exhausted through the …………… outflow valve &, ……….% through the ………….. outflow valve. Why?
20%, forward, 80%, aft.
This improves smoke removal & ventilation.
What prevents over pressure conditions?
2 positive pressure relief valves.
Each valve incorporates dual sensing for 2 levels of pressure relief.
Where are the 4 negative pressure relief vents located?
2 on each side of the forward fuselage
When could a negative pressure condition occur?
If the airplane descends at a rate too fast for the cabin pressure controller.
Why do the outflow valves begin to close during the t/o roll?
To minimise pressure transients at lift-off
What’s the max cabin altitude?
8,000 ft
Max differential pressure?
9.1 psi
The target descent altitude for the cabin is set at ? Why?
190 ft BELOW airport field elevation.
This design is for structural reasons & ensures that the a/c lands somewhat pressurised.
At touch down, what do the ASCPC valves do?
Open the outflow valves, slowly at first & then at a greater rate until the a/c is fully depressurised.
If the t/o field elevation is higher than 8,000 ft, the cabin descends to the target altitude while the a/c is climbing, it does this at what rate of descent?
Limited to 300 fpm, unless the max pressure differential is in danger of excess.
The landing altitude used by the ASCPCs depends upon the distance of the airplane from the departure airport. If the distance from the departure airport is less than ……… miles or, less than halfway along the route, the ASCPCs use the departure airport’s landing altitude to the nearest …… feet
400 miles,
100 feet
After the a/c passes the halfway point or travels more than ……… miles, the landing altitude changes to the destination airport’s elevation to the nearest ……. feet
400 miles
100 feet
Cabin Altitude exceedance’s:
Cabin alt display amber above 8,500 ft
Cabin alt display red above 10,000 ft
The landing altitude selector (manual setting) has 2 positions, first detent …… foot increments, second detent …… increments
100 foot
500 foot
What is the function of the negative pressure relief vents?
They prevent negative pressure differentials
