SWA B737 - Pressurization

Question 1

(Pressurization) What are the two different modes of operation of the Pressurization System?

Answer 1

• Automatic

* Manual

Question 2

(Pressurization) How many automatic Cabin Pressure Controllers are on the airplane?

Answer 2

2 (Alternates every flight which is the main one and which one is the backup)

Question 3

Pressurization) At what Cabin Altitude will the DC Powered Motors automatically close the outflow valve?

Answer 3

14,500 feet

Question 4

(Pressurization) What does an illuminated ALTN light on the Pressurization Control Panel on the Overhead Panel indicate?

Answer 4

The Pressurization Mode Selector is moved to ALTN, and the other controller is activated. (The aircraft is still in the automatic Pressurization Mode)

Question 5

(Pressurization) What happens when a Fault is detected in one of the Cabin Pressure Controllers with the Mode Selector Switch in the AUTO position?

Answer 5

• The other Cabin Pressure Controller automatically takes over.
• The AUTO FAIL light on the Pressurization Panel on the Overhead Panel illuminates.
• The ALTN light on the Pressurization Panel on the Overhead Panel illuminates.

Question 6

(Pressurization) How can you tell if one or both Cabin Pressure Controllers failed?

Answer 6

• If only one fails both the AUTO FAIL light and the ALTN light would be illuminated.
• If both failed only the AUTO FAIL light would be illuminated.

Question 7

(Pressurization) What are reasons the AUTO FAIL light will illuminate?

Answer 7

• Controller Fault
• Excessive Differential Pressure
• Excessive Rate of Cabin Pressure Change
• Loss of DC Power
• High Cabin Altitude
• Outflow Valve Control Fault

Question 8

(Pressurization) What Cabin Altitude causes the Cabin Altitude Warning Horn to sound?

Answer 8

10,000 feet

Question 9

(Pressurization) How do you cancel the Cabin Altitude Warning Horn?

Answer 9

• Pressing the ALT HORN CUTOUT switch on the Pressurization Panel.
• Reducing the Cabin to below 10,000 Cabin Altitude.

Question 10

Pressurization) What powers the Manual Mode Motor?

Answer 10

DC Battery Bus (in the case of losing all AC Power, the Pressurization would still work in Manual Mode)

Question 11

Pressurization) True or False: The Outflow Valve switch on the Pressurization Panel is spring loaded to the center position.

Answer 11

true

Question 12

(Pressurization) What does an illuminated MANUAL light on the Pressurization Panel indicate?

Answer 12

The Pressurization System is operating in the Manual Mode.

Question 13

(Pressurization) When landing in the Manual Mode, what is something you want to do before entering the landing pattern?

Answer 13

Slowly position the Outflow Valve switch to full open to depressurize the airplane. Verify the differential pressure is zero.

Question 14

(Pressurization) What safety do we have if the Outflow Valve fails in the closed position or the Differential Pressure gets too high?

Answer 14

Two Positive Pressure Relief Valves (no input is needed from the Flight Deck for these to operate, if the pressure inside the aircraft gets too high they automatically blow the excess air overboard)

Question 15

(Pressurization) How does the Negative Pressure Relief Valve work?

Answer 15

It is a flapper on a hinge, when the pressure outside the aircraft exceeds that of inside the flapper opens and equalizes the pressure (if in an Emergency Descent for example)

Question 16

(Pressurization) What does an illuminated OFF SCHED DESCENT light on the Pressurization Panel indicate?

Answer 16

indicating that the airplane descended before reaching the cruise altitude set in the FLT ALT indicator

Question 17

(Pressurization) If you have to return to field will the Pressurization automatically return to the departure field elevation, without crew input?

Answer 17

yes - UNLESS you changed the altitude in the FLT ALT window on the pressurization panel

Question 18

(Pressurization) When does the Pressurization System enter the Climb Phase?

Answer 18

obce both main landing gear are off the ground (the cabin will climb at a rate proportional to the aircfaft rate of climb

Question 19

(Pressurization) When does the Pressurization enter the Cruise Phase?

Answer 19

when the aircraft climbs within 0.25 psi of the altitude set in FLT ALT windows ( the system maintains a proportionall pressure differential between the airplane altitude and the cabin altitude)

Question 20

(Pressurization) When does the Pressurization System activate the Descent phase?

Answer 20

when the aircraft descends 0.25 psi below the selected FLT ALT (the controllers descend the cabin at a proportional descent schedule to slightly below the altitude set in the LAND ALT window