21 Airconditioning

Question 1

Where is our Cabin pressurisation, heating and cooling sourced from for the aircraft?

Answer 1

Engine bleed air and the RH engine aircon compressor.

Question 2

How is conditioned air distributed throughout the aircraft?

Answer 2

Via 2 ducting systems connected at blower, outlets at cabin lower sidewall = heating/pressurisation, adjustable outlets in headliner = recirculation and cooling.

Question 3

How is temperature regulation achieved?

Answer 3

Cabin temp controller mounted in the center cabin headlining. It can be controlled manually or automatically.

Question 4

What do the outflow and safety valves have installed in the event of excess cabin pressure?

Answer 4

max differential valves.

Question 5

How does your pressurisation control operate?

Answer 5

The pressurisation controller operates the outflow valve depending on the vacuum applied to it from the controller.

Question 6

What happens if your DUMP switch is actuated?

Answer 6

the 2 solenoid valves open porting vacuum to the safety valve opening it and dumping cabin pressure.

Question 7

What condition is required for the aircon system to activate?

Answer 7

left bypass valve must be in the fully closes position in response to the cool commands of the cabin temp controller.

Question 8

What item removes heat from the hot cabin air?

Answer 8

evaporator coils

Question 9

What protective measures are there for the airconditioning system?

Answer 9

Over pressure and underpressure switches.

Question 10

What is the purpose of the bypass valves located in each wing?

Answer 10

if heat is required the bypass valves full open, if LESS heat is required they will close directing bleed air through the RAM air heat exchangers.

Question 11

What provides additional heating?

Answer 11

An electric heater located aft of the forward plenum. Only functional when the aircraft is on the ground.

Question 12

What refrigerant is used in the aircon system?

Answer 12

R134A

Question 13

Explain the operation of the temperature controller.

Answer 13

Manages the dual zone of the 2 crew and cabin zones, thermistors measure the temp and are monitored by the controller manipulating the bleed air bypass valves in the wing.

Question 14

How are cockpit and cabin temperatures achieved?

Answer 14

By combining, crew/cabin ambient air, cooled air and heated engine bleed air.

Question 15

What responsibilities does the temp controller have?

Answer 15

open and close duct valves to maintain crew and cabin temps, evaporator blower speeds, compressor clutch, condenser blower.

Question 16

The flow control unit FLOWPACK controls the flow of?

Answer 16

Ambient air and engine bleed air.

Question 17

Ambient air flow modulating valves is operated by which squat switch and why?

Answer 17

Left, to prevent debris entering the system whilst on the ground.

Question 18

Flow pack FLOW rate is determined by which components?

Answer 18

Bleed air flow transducer, ambient air temp sensor, electronic controller.

Question 19

On take off what happens to the ambient air valves of the FLOWPACK?

Answer 19

left is immediately open, followed by the right which is on a time delay to prevent pressurisation surges.

Question 20

With the aircraft climbing and temps cooling what happens to the ambient air valve?

Answer 20

it slowly closes un till 0 F is reached where it will be fully closed.

Question 21

What controls the rate of ambient air through the controller?

Answer 21

Atmospheric temperature, at high temperatures, when temps are high bleed air is minimised, when low ambient air is reduced.

Question 22

What is installed at the juncture of the bleed air ducts to prevent cabin press loss in the event of an engine out condition?

Answer 22

check valves are installed.

Question 23

What warning system is there in the event of duct overheating of the distribution system?

Answer 23

DUCT OVERTEMP annunciator activating at 300 F

Question 24

Enviromental bleed air flow can be controlled by a NORMAL-AUTO-LOW toggle switch, what is its purpose?

Answer 24

LOW - reduces bleed air by half making sure take off power is available, AUTO - recommended setting auto controls, NORMAL - increased heating and pressurisation.

Question 25

Where do your outflow and safety valve sense atmospheric pressure?

Answer 25

Vents that protrude through rear bulkhead.

Question 26

what switch activates Cabin pressurisation in flight.

Answer 26

Left squat switch , or bypass by using the test toggle switch. or both if MOD installed.

Question 27

What prevents cabin negative pressure?

Answer 27

Relief diaphragm in the outflow valve.

Question 28

What controls your vaccuum to the out flow and safety valves?

Answer 28

Preset (N.O) and safety solenoids (N.C).

Question 29

If cabin pressure altitude exceeds 12,500 +0 - 500 what happens?

Answer 29

Cabin altitude pressure switch closes and CABIN ALT annunciator illuminated.

Question 30

What annunciator will you receive when cabin diff becomes excessive?

Answer 30

a red CABIN DIFF HI annunciator.

Question 31

What is the purpose of the altitude limit controllers?

Answer 31

Limit cabin alititude to 13,500 +/- 1500 feet by automatic overide of an open outflow/safety valve signal.

Question 32

How is the electric heat system powered?

Answer 32

Via a GPU, not using the battery

Question 33

Where are your electric heat panels located?

Answer 33

centre aisle floorboard, cockpit floorboard. Cargo door (If fitted)

Question 34

How many servos does the aircraft have to direct air through the distribution system?

Answer 34

5

Question 35

How long must the electric heat system be turned off before ground start?

Answer 35

2 minutes.

Question 36

What N1 speed must you achieve to activate the clutch of the aircon compressor?

Answer 36

62%

Question 37

What controls the flow of air across your condensor?

Answer 37

Nose landing gear down switch, gear down = blower motor, gear up = ram air.

Question 38

What overpressure protection do you have for the aircon system?

Answer 38

An over pressure switch and an overpressure relief valve located near the receiver/dryer. 450 psi

Question 39

Where is your temperature controller located?

Answer 39

under center isle floor zone 143

Question 40

How many temp sensors does the automatic temp controller draw from?

Answer 40

6 - 2 duct temp, 2 for crew/cabin temp, 1 mixing box, 1 oat