Pressurisation System

Question 1

Above what altitude does the cockpit become pressurised?

Answer 1

8000ft

Question 2

How is the pressurisation seal inflated?

Answer 2

Air is fed to it from the bleed air inflow.

Question 3

What Delta-P will the system aim to maintain above 18,069ft?

Answer 3

A Delta-P of 3.6 +- 0.2 PSI

Question 4

When would a red CKPT PX caption illuminate?

Answer 4

If Delta-P is between 3.9 to 4.0 PSI.

Question 5

How does the bleed air inflow facilitate cockpit pressurisation?

Answer 5

It provides positive pressure to the cockpit and inflates the pressurisation seal.

Question 6

If Delta-P goes above 4.0 PSI, what happens?

Answer 6

The Safety Valve opens, releasing the excess pressure.

Question 7

In broad terms, how is pressurisation maintained.

Answer 7

Positive pressure is provided by the bleed air inflow. A control valve is opened or closed to release or trap air in the cockpit.

Question 8

What happens when the Pressurisation switch is set to DUMP?

Answer 8

Power to the dump solenoid is cut which in turns opens the control valve. Bleed air (from the engine) is still entering the cockpit from the bleed air inflow valve.

Question 9

What happens when the Pressurisation switch is set to RAM/ DUMP?
What is the purpose of this?

Answer 9

The control valve and the fresh air valve both open. The Defog valve is closed.
This reduces engine air to the cockpit and increases fresh air to help vent fumes.