Pressurization

Question 0

When will the overboard exhaust valve be open?

Answer 0

On the ground and inflight with a low cabin differential pressure, the overboard exhaust valve opens and warm air from the E & E bay is discharged overboard.

Question 1

Where are the main outflow valve and overboard exhaust valve?

Answer 1

Main outflow: underneath near the rear of AC

Overboard exhaust valve: underneath AC near the entry door

Question 2

Inflight, at higher cabin differential pressures, the overboard exhaust valve is normally closed and exhaust air is diffused to the lining of :

Answer 2

Forward cargo compartment

Question 3

When will the overboard exhaust valve be open in flight?

Answer 3

The overboard exhaust valve will open if either pack switch is in HIGH and the recirculation fan is OFF. This allows for increased ventilation in the smoke removal configuration

Question 4

Where do the press controllers get their altitude info from?

Answer 4

ADIRUs

Question 5

The main outflow valve uses what type of pwr?

Answer 5

DC

Question 6

The 737 can maintain sea level pressure up to what altitude?

Answer 6

18,500

Question 7

Where are the cabin pressure relief valves?

Answer 7

Right next to cabin outflow valve

Question 8

Where are the neg press relief valves?

Answer 8

Slightly forward and outside of the outflow valve

Question 9

When cabin alt does the cabin alt warning horn activate

Answer 9

Cabin alt :10,000

Question 10

How many cabin altitude modes are there and which ones provide automatic operation?

Answer 10

Three cabin altitude control modes are available, two of these modes provide full automatic operation. The modes are:

• Automatic
• Alternate
• Manual

Question 11

When does the cabin start to pressurize?

Answer 11

After a 1.5 second delay, when the throttles are advanced to achieve an N1 greater than 60% and an N2 greater than 89%, the controller modulates the main outflow valve toward close, slightly pressurizing the cabin.
This ground pressurization of the cabin makes the transition to pressurized flight more gradual for the passengers and crew, and also gives the system better response to ground effect pressure changes during takeoff.

Question 12

When does the OFF SCHEDULE DESCENT light come on?

Answer 12

An amber OFF SCHED DESCENT light illuminates if the airplane begins to descend without having reached the planned cruise altitude, for example, a flight aborted in climb and returning to the takeoff airport.
The MASTER CAUTION lights and AIR COND annunciator light will also illuminate.