Pressurisation

Question 1

What function does the differential valve serve?

Answer 1

Compare cabin pressure to outside static air pressure to regulate the cabin maximum differential pressure at 8.9 psi +/- 0.1 psi

Question 2

How does the Cabin Limit Valve work?

Answer 2

Prevents cabin altitude from exceeding 13000 ft +/- 1500 ft

Question 3

Does the presurisation system work in EMERGENCY?

Answer 3

Yes

Question 4

Does the pressurisation system have electronic components.

Explain the A B and C Solenoids

Answer 4

Solenoids A B and C essentially control pressurisation on the ground and on take off.

Thrust position < 80% when on the ground (left squat switch)
Valve A - de-energises closed inhibiting the reference signal from the pressure controller to the pneumatic relay.
Valve B and C, - energise open allowing full vacuum to the outflow valve to full open.

Thrust position > 80%
Valves B and C de-energise closed replacing raw vacuum to the outflow valves with regulated vacuum.
Valve A energises Open.