skyblue CBT pnemuatics

Question 1

what is the purpose on the pneumatic system?

Answer 1

to provide high pressure air to\;

• air con
• pressurisation
• de icing

Question 2

where is air tapped from?

Answer 2

high and low pressure stages of the compressor

Question 3

what provides air to the air con packs?

Answer 3

the respective side

Question 4

where does air for the de icing system come from?

Answer 4

high pressure stage

Question 5

how does low pressure air enter the bleed air system?

Answer 5

through a one way check valve

Question 6

what supplements bleed air when power is not high enough from the low pressure pneumatics?

Answer 6

high pressure bleed

Question 7

what does the HP valve require to open?

Answer 7

electrical power and pneumatic pressure

Question 8

what powers the HP valves?

Answer 8

the respective DC bus

Question 9

what will happen to the HP valve if electrical power is lost?

Answer 9

it will close

Question 10

when will the high pressure bleed air temperature sensor close the HP valve?

Answer 10

more than 270C

Question 11

when will the HP valve reopen after closing due to an overheat?

Answer 11

after a cooling period

Question 12

what ultimately determines the position of the high pressure valve?

Answer 12

pressure output at the low pressure stage

Question 13

at what LP pressure output will the HP valve open?

Answer 13

22psi

Question 14

what prevents backflow into the LP part when HP valve is open

Answer 14

LP check valve

Question 15

how is the bleed valve controlled and operated?

Answer 15

electriclly controlled and pneumaticaly operated

Question 16

what closes the bleed valve if power is lost?

Answer 16

solenoid

Question 17

what powers the bleed valves?

Answer 17

DC ESS BUS

Question 18

when will the bleed valve automatically close?

Answer 18

if power or airflow is lost

Question 19

where are the temperature sensors located?

Answer 19

downstream of the bleed valve

Question 20

at what duct temperature will the bleed valve and HP valve automatically close?

Answer 20

274C

Question 21

when will a bleed automatically close?

Answer 21

• leak
• over temp
• engine failure on opposite side
• fire handle pulled

Question 22

when will the left bleed valve only automatically closed?

Answer 22

prop brake engagement

Question 23

what is the purpose of the crossfeed?

Answer 23

to feed both packs with one engine on the ground only

Question 24

when is the crossfeed open on the ground?

Answer 24

when right engine is running and supplying air

Question 25

when should a pack be turned off in flight?

Answer 25

when a bleed valve fails

Question 26

what is max altitude with only one bleed operating?

Answer 26

20000ft

Question 27

what powers the crossfeed valve?

Answer 27

DC BUS 1

Question 28

where does the leak detection system look for bleed leaks?

Answer 28

1. wing leading edges
2. wing to fuselage fairings
3. upper/lower fuselage floor
4. air conditioning pack area

Question 29

what is the leak detection tube made of?

Answer 29

control lead surounded by an insulating material and surrounded by an inconel tube

Question 30

how is a leak detected?

Answer 30

increasing temperature reduces the resistance in the leak detection loop until it is grounded at 124C. this triggers an AIR LEAK caution

Question 31

what happens 1 second after an air leak is sensed?

Answer 31

pack, bleed and HP valves close. System is inop for rest of the flight

if the leak was in the left system, the crossfeed will also close

Question 32

what controls the HP and bleed valves from the flight deck?

Answer 32

BLEED button

Question 33

what psi does a bleed valve require to open?

Answer 33

10psi

Question 34

when do we get an AIR BLEED caution?

Answer 34

when switch position disagrees with bleed valve position, overpressure, overheat or leak

Question 35

when does the OVHT illuminate?

Answer 35

the temp sensor downstream of the bleed valve exceeds 274C