Pneumatics

Question 1

How many controllers does each pack have?

Answer 1

2 auto and standby

Question 2

What is are the Pack Control Selectors for?

Answer 2

Auto: Lets Boeing manage PACK VALVE automatically
STBY: Manages the temperature that I select
Normal N : Regulates back outlet temp to a constant moderate temp
Cool C: Sets the pack to full cold
Warm W: Sets pack to full warm

Question 3

What are the 3 sources for bleed air?

Answer 3

APU
Ground Source
Engines

Question 4

What is the APU Shuffle?

Answer 4

Procedure to prevent inadvertent shutdown by overcoming the check valve

Question 5

Walk me through the APU Shuffle.

Answer 5

1. Turn Bleed Air switch for APU OFF – (Prevents air from going into 4 ducts)
2. Packs from AUTO to OFF- (closes both pack valves)
3. Turn APU bleed Air Switch back to ON (give control back to Boeing to populate 4 ducts)

Question 6

When I select GRND during engine start, what will the APU do?

Answer 6

Increase pneumatic pressure during start.

Question 7

What will the APU bleed air valve do when the engine start is over?

Answer 7

CLOSE- it is only OPEN during start

Question 8

Just started right engine from APU- what is the position of the R Engine Bleed Air Valve

Answer 8

WIDE OPEN!
APU Bleed Air Valve?- Closed
Why? Boeing logic.
Must have air going through all 4 ducts to make sure all 11 items work

Question 9

What is the flow of the air to the zones?

Answer 9

Mixing Master Trim Air to Pack Air

Air comes through 4 ducts through the pack valves.
Past the pack valves and prior to the air cycle machine and has warm air tapped off to the master trim air system. Master trim air adds warm air through each individual zone control valve to make the temperature what was selected.

Rest of air is sent to the Air Cycle Machine where they make it into the coldest temperature requested air in the 4 zones of our cabin and can maintain within 1 degree. .
Coldest zone control valve is closed because the pack air is enough.

Question 10

How does each zone basically maintain its temperature?

Answer 10

Each zone has zone control valve that works with master trim air system to allow enough warm air into the pack air to give you whatever you ask for.

Question 11

What is the cockpit zone temperature zone range? Range is the valve position!
How do you know the temperature is good?

Answer 11

18 degrees - 30 degrees C or
65-85 degrees F

Ask the Captain

Question 12

L & R Recirc Fans do what?

Answer 12

Recirculate Cabin Air!
Take cabin conditioned air and cycle it back through recirculation system, filtered and pushed back through common manifold and then back into the cabin.
*Purpose is to allow packs to work less than they need to- air is already the right temperature.

just takes already conditioned air that is the temp we want it from the cabin and allows it to be filtered and pushed into the common manifold and back to the 4 zones. Allows the packs to work less hard

Question 13

What part of the air that reaches the cabin is coming from the RECIRC fans?

Answer 13

Over 50% of air that actually makes it to the cabin. Allows the

Question 14

When are the packs in high flow?

Answer 14

When they are not in normal flow?

Question 15

When packs are in HIGH flow how much more fuel are they using?

Answer 15

.3% more fuel per pack

Question 16

Left Pack is associated with____Recirc Fan

Answer 16

Forward Recirc Fan

Question 17

If I have to run my packs at high flow what will the dispatcher do?

Answer 17

Give me more fuel

Question 18

Right Pack is associated with ___ recirc fan

Answer 18

Aft Recirc fan

Question 19

Why would my pack go to high flow? Both Engines Running

Answer 19

Both Engines Running for these logic to be made true:
-If one of my packs has a fault- the other pack will go to high flow

Both Engines Running
-If I lose the RECIRC fan with a fault- it’s partner Pack will go to high flow

Question 20

When is a pack inhibited from going to high flow? One Engine Running

Answer 20

If I have a single engine shut down- (so no pack) OR single pack failure- the remaining working pack is inhibited from ever going to high flow.
Why? If I lose both packs, I depressurize!
I don’t want to take any chance of making that pack work too hard and fail.

Question 21

When would I see four INOP lights on the Temperature Control Panel?

Answer 21

I turned the Master Trim Air switch off-I de-energized them all.

Fault of Master Trim Air System

Question 22

What can bring on one single INOP light on the Temperature Control Panel?

Answer 22

1. I have a fault with individual control valve

2. I have taken the controller and turned it to off

Question 23

Are my recirc fans Fault or Agree/Disagree lights?

Answer 23

Fault

Question 24

Recirc Fans are powered by what BUS?

Answer 24

Utility Bus- If I don’t have Utility Buses I don’t have recirc fans

Question 25

Target Temperature by the PACKS

Answer 25

Lowest of the Four Zones
65 degrees to 85 degrees (selectable range)
Celcius 18 degrees to 30 degrees

Question 26

Pack Reset Switch Lights INOP and PACK OFF mean what?

Answer 26

INOP: Can come on by itself- The temperature is too high from what was requested. Valve stuck OR
There is a control fault.

Take controller from AUTO-N
If INOP light goes out- it is a controller problem
If it doesn’t go out, there is a problem with pack valve being stuck in position that isn’t giving me my coldest air.

PACK OFF: Can come on by itself - Internal Overheat causes a self shutdown. Pack valve is closed.

Both: Internal overheat
Auto Shuts Pack Off
After cools -you can do 1 reset

Question 27

Master Trim Air Systems

Answer 27

Mixes with the zones that are requesting higher temp than the coldest to warm it up to what is requested.

Question 28

Where does cold air come from for E and E compartment?

Answer 28

Pack Air

Question 29

What is the flow of air to get the air to the zones cooler or warmer?

Answer 29

Air comes off engine- Cooled by the Air Cooler

Question 30

Inop Light on one Recirc Fan?

Answer 30

-On side PACK goes to high flow

Question 31

If I don’t have utility busses what would happen to my packs if both engines are running?

Answer 31

They both go to high flow
Work harder and last for less time.
.3 + .3 =.6% fuel flow increase