Pneumatics

Question 1

Which stage of compression normally supplies bleed air from the engines?

Answer 1

The 8th stage.

Question 2

Which stage of compression augments the primary source of bleed air?

Answer 2

The 13th stage.

Question 3

How are the pneumatic crossfeed valves operated?

Answer 3

With cables attached to the handles in the cockpit.

Question 4

Are the crossfeed valves designed to be air tight?

Answer 4

No, there may be a little bit of leakage.

Question 5

Which bus powers the pneumatic pressure start gauge?

Answer 5

The AC emergency bus.

Question 6

How much PSI is required to operate the airfoil anti ice system?

Answer 6

A minimum of 20 PSI.

Question 7

Which bleed air supply stage has a check valve?

Answer 7

The 8th stage.

Question 8

Which bus powers the 13th stage augmentation valves?

Answer 8

Respective DC bus.

Question 9

To what position will the 13th stage augmentation valves move if DC power fails?

Answer 9

They will fail to the close position.

Question 10

In which two modes can the 13th stage augmentation valves operate?

Answer 10

Either pressure sensitive or temperature sensitive.

Question 11

When will the 13th stage augmentation valves be temperature sensitive? Will air still be supplied to the air conditioning units?

Answer 11

With the anti ice on. Yes, air will still be supplied but temperature regulation has priority.

Question 12

Can APU air be turned on in flight?

Answer 12

No.

Question 13

What is the power source for the engine starters?

Answer 13

APU pneumatic air.

Question 14

Can the APU start an engine while supplying air conditioning?

Answer 14

No.

Question 15

When will the red TAIL COMPT TEMP HI light come on? How many sensors are in the tail cone?

Answer 15

When temperature in the tail compartment rises to 180 F. There are 2 sensors.

Question 16

Where does the air from the L ACM and the R ACM first ‘go’ after leaving each machine?

Answer 16

To a mixing chamber.

Question 17

Are there separate ducts from the air mixing chamber to the cockpit and the cabin?

Answer 17

Yes.

Question 18

If one ACM system fails enroute are you required to descend?

Answer 18

No, you may stay at altitude provided that the sole ACM can maintain cabin pressure.

Question 19

Can you be dispatched with one ACM inoperative?

Answer 19

Yes, maximum operating altitude is FL250.

Question 20

How are the heat exchangers cooled in flight?

Answer 20

By ram air from a duct at the base of the vertical stabilizer.

Question 21

Where does the heat exchanger ram air exit the aircraft?

Answer 21

On either side of the tail compartment through rectangular exits.

Question 22

How are the heat exchangers cooled inflight?

Answer 22

By ground blower fans.

Question 23

Where do the ground blower fans exhaust?

Answer 23

Through louvers on either side of the aircraft.

Question 24

Which bus is the source of power for the ground blower fans?

Answer 24

The respective AC generator bus.

Question 25

Which bus is the source of power for the HP bleed supply switches?

Answer 25

The emergency DC bus.

Question 26

With the HP bleed supply switches off what is the function of various fans and valves?

Answer 26

The flow control valve, pressure regulator, and shutoff valve are all closed preventing any pressurized air from entering the ACM. The ground blower fan is also turned off.

Question 27

Which bus is the source of power for the temperature control valves when in the auto position?

Answer 27

Respective AC bus.

Question 28

Which bus is the source of power for the temperature control valves when in the manual mode?

Answer 28

The emergency AC bus.

Question 29

What causes the air conditioning system to automatically shut down?

Answer 29

The system will automatically shut down when compressor discharge increases excessively, and excessive temperatures occur in either the outlet duct or the turbine inlet.