Pressurization

Question 1

The pressurisation system consists of:

Answer 1

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

Question 2

What do the ASCPCs do?

Answer 2

The air supply cabin pressure controllers (ASCPCs), send & receive data necessary to control the pressurisation system

Question 3

Is the L or R ASCPC considered the master controller?

Answer 3

Left

Question 4

If valid ASCPC cabin pressure is not available, ………………. uses cabin pressure from the remote pressure sensor

Answer 4

AIMS

Question 5

Data to & from the PRESSURISATION panel is provided from which bus?

Answer 5

629

Question 6

Can the outflow valves be manually operated?

Answer 6

Yes, from the pressurisation panel

Question 7

2 ……………. are used to regulate cabin pressure

Answer 7

(2) Outflow valves

Question 8

Normally……….% of the air is exhausted through the …………… outflow valve &, ……….% through the ………….. outflow valve. Why?

Answer 8

20%, forward, 80%, aft.

This improves smoke removal & ventilation.

Question 9

What prevents over pressure conditions?

Answer 9

2 positive pressure relief valves.

Each valve incorporates dual sensing for 2 levels of pressure relief.

Question 10

Where are the 4 negative pressure relief vents located?

Answer 10

2 on each side of the forward fuselage

Question 11

When could a negative pressure condition occur?

Answer 11

If the airplane descends at a rate too fast for the cabin pressure controller.

Question 12

Why do the outflow valves begin to close during the t/o roll?

Answer 12

To minimise pressure transients at lift-off

Question 13

What’s the max cabin altitude?

Answer 13

8,000 ft

Question 14

Max differential pressure?

Answer 14

9.1 psi

Question 15

The target descent altitude for the cabin is set at ? Why?

Answer 15

190 ft BELOW airport field elevation.

This design is for structural reasons & ensures that the a/c lands somewhat pressurised.

Question 16

At touch down, what do the ASCPC valves do?

Answer 16

Open the outflow valves, slowly at first & then at a greater rate until the a/c is fully depressurised.

Question 17

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?

Answer 17

Limited to 300 fpm, unless the max pressure differential is in danger of excess.

Question 18

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

Answer 18

400 miles,
100 feet

Question 19

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

Answer 19

400 miles

100 feet

Question 20

Cabin Altitude exceedance’s:

Answer 20

Cabin alt display amber above 8,500 ft
Cabin alt display red above 10,000 ft

Question 21

The landing altitude selector (manual setting) has 2 positions, first detent …… foot increments, second detent …… increments

Answer 21

100 foot

500 foot

Question 22

What is the function of the negative pressure relief vents?

Answer 22

They prevent negative pressure differentials