Pressurization

Question 1

When do you pressurize?

Answer 1

Thrust levers moved into the takeoff range
(this moves outflow valve closed during takeoff)

Captains Altimeter ONLY- lets system know when you’re at standard and not at standard

Question 2

What part does the FMC play in pressurization of your airplane?

Answer 2

No part in pressurization

Question 3

How many controllers are part of the pressurization system?

Answer 3

3 (2 AC, 1 DC) It’s on the knob
Auto 1- AC Powered Automatic Control
Auto 2-AC Powered Automatic Control
MAN- DC motor that lets me control the cabin manually

Question 4

What Systems are inputs of my pressurization system

Answer 4

Main Gear Air Ground Logic
Air Data Computer- As temp and pressure change it knows this to place inputs in
Captains Altimeter

Question 5

What is crew required to do with the Pressurization Controller?

Answer 5

1. Set Landing Field Elevation
2. Select Auto 1 or Auto 2 (whoever is flying CA or FO)
3. Verify AUTO RATE is in index position (climb 500fpm descent 300 fpm)

Question 6

Land after 8 hour flight, what is target cabin altitude to select?

Answer 6

200’ lower than the elevation of where you are landing. But never to exceed .125 inches if differential pressure

Question 7

When I land what does main gear air logic do?

Answer 7

Allows the outflow valve to go wide open to depressurize.

Question 8

200’ equals what?

Answer 8

.125 PSI

Question 9

How does the cabin climb?

Answer 9

Relative to the airplane climb.

Question 10

Airplane Logic of Climb Cruise Descent

Answer 10

Climb, Cruise, Descent
Level off in 1 minute Climb will change to Cruise-
1000’ dictates climb back to cruise
Boeing when you go into cruise has programmed into pressurization system to look at final cruise altitude and cabin altitude you’re at and your landing altitude. Will take the higher of the landing altitude and cabin altitude to calculate new PSI differential. Will climb the cabin to this!

I.e. Denver example from class-

Question 11

Target of this pressurization system FL35 or greater should be what?

Answer 11

8.6 PSI
(if it is higher- tell Captain- maybe outflow valve stuck or not working properly)

The system will do it’s best to maintain 8.6 all the way up to Flight Level 350 and higher

Question 12

Max Differential Pressure where Overpressure Relief Valve is starting to kick in is ___ PSI. Doors will open up and let pressure decrease to a safe PSI.

Answer 12

9.1 PSI

Question 13

Coming into Denver, I put in my arrival- Last altitude on arrival is 4000’. Power off descent all the way down the STAR. What does the controller do?

Answer 13

More than 1000’ fpm CRUISE mode changes to DESCENT mode

Goal is to have cabin altitude stop 200’ below LFE .125

Question 14

Flying in AUTO 1- lose AUTO 1, what happens?

Answer 14

AUTO 1 will automatically switch to AUTO 2

Question 15

What if I move Mode Select to Auto 1 to Manual with everything powered normally?

Answer 15

Nothing will happen to outflow valve it’ll freeze and it will just show AUTO INOP light above the knob. Same as if there is a failure- the outflow valve will stop and not move!

Question 16

When would you see AUTO INOP light on Mode Select Panel

Answer 16

AC failure of AUTO 1 or AUTO 2

Moving the controller to MAN

Question 17

How many Negative Pressure Relief Valves?

Where are they?

Answer 17

5 Negative Pressure Relief Valves

1 on left side of airplane forward of positive pressure relief doors AIRCRAFT LEFT
2 on fwd cargo door AIRCRAFT RIGHT
2 on aft cargo door AIRCRAFT RIGHT

Question 18

How many Over Pressure Relief Valves?

Answer 18

2 Forward of left wing root

Question 19

CABIN ALT light comes on when?

Answer 19

10000’
Warning system is our ears!
PUT YOUR MASK ON and call for Immediate Action Item Checklist
“CABIN ALT”
“RAPID DECOMPRESSION”
I need to tell ATC “i’m losing my cabin, I need to descend what heading do you want me on to avoid traffic.”

Question 20

Cabin altitude continues to climb and reaches 11,000’ what happens? What is it called?

Answer 20

CABIN RATE LIMITING!
Separate signal sent to outflow valve by DC power to command it CLOSED.

“If you reach 11000 feet with DC power closing the outflow valve it is called Cabin Rate Limiting”

Question 21

Cabin Altitude reaches 14,000’ what happens?

Answer 21

Rubber Jungle Deployment Automatically (12 mins supply)

Question 22

Once cabin goes back below 8,500’ what happens?

Answer 22

Warning resets in case it re climbs above 10,000’

Question 23

At 11,000 feet cabin altitude what happens?

Answer 23

“CABIN RATE LIMITING”

Outflow valve is closed by DC power

Question 24

Flying Denver (field elevation 5430) to Tulsa at sea level, how would you set up the panel?

Answer 24

Go to AUTO __ depending on who is flying
Landing elevation will be at 0
Rate will turn to the diamond index
Climb up to FL 290,

Question 25

What is the comparison of your landing airport field elevation vs the Boeing logic determined cabin altitude ?

Answer 25

Boeing logic will set the cabin for the higher of the two. (i.e Tulsa to Denver at FL 290) Boeing will look at what it thinks you should be at for FL290 and then look at the 5400’ Field Elevation at Denver. Will pick the greater of the two to set the cabin at.

Question 26

If I have a dual bus fault, what will status of pressurization be?

Answer 26

AUTO INOP light

Means have lost both AUTO 1 & AUTO 2

Question 27

What is the name of the Manual DC controller?

Answer 27

Paul!! ME!

Question 28

If I were inflight with all electrical systems working and Auto 1 & 2 operating normally and I selected MAN?

Answer 28

Outflow valve will not do anything until you manually control it using the knob.

Question 29

Cabin Differential Pressure Gauge

Answer 29

Above FL 350? 8.6

Below 350? Whatever Boeing decides