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United 737 > Air Conditioning > Flashcards

Flashcards in Air Conditioning Deck (51):
1

The ____pack provides air directly to the flight deck with excess air flowing to the mix manifold.

Left

2

The ____pack and the __________ also enters the mix manifold which is then distributed to the cabin.

right , recirculation system

3

A _____ pack in ____flow will maintain pressurization and acceptable temperatures throughout the a/c operating envelope.

single, high

4

The APU can supply suffient bleed air for ____ packs on the ground but only ____ pack in flight.

2, 1

5

T/F: A single engine can be used to operate 2 packs.

FALSE.

6

AUTO on the temperature selector does what?

provides automatic temp control for that part of the cabin.

7

ZONE TEMP lights indicate what?

a problem with the associated zone temperature. The duct has overheated and the trim air modulating valve closes to prevent further overheat. A TRIP RESET can work to reopen the valve provided the duct has cooled.

8

CONT CAB light indicates:

a duct temp overheat or failure of both flight deck pri and stby temp control.

9

FWD or AFT CAB indicates:

a duct temp overheat

10

RAM DOOR FULL OPEN indicates what:

ram air doors in the full open position (blue light)

11

what does TRIM AIR do?

opens and closes the pressure regulating and shutoff valve.

12

L or R RECIRC FAN in auto means :

fan operation is dependent on the PACK settings.

13

PACK light indicates:

the pack has tripped off or both pri and stby pack controls have failed or an overheat is sensed.

14

If a fault condition has been corrected and the TRIP RESET is pressed what happens?

resets the BLEED TRIP OFF, PACK or ZONE TEMP lights and the related valves open.

15

Conditioned air for the flight deck branches into what 3 things:

floor, ceiling and foot level outlets. Provides warming or cooling and defogging.

16

How is conditioned air routed to the cabin?

via an overhead distribution duct

17

With both packs in AUTO, what happens when one pack stops?

the other goes to high flow.

18

When does automatic switching for single pack ops not occur?

on the ground or with flaps extended in flight.

19

With APU bleed on and BLEED switches to OFF, what happens?

The packs go to high flow, regardless of teh # of operating packs or air/ground status or flap position.

20

T/F: Ram air pack doors open and close normally in flight, depending on cooling requirements.

True.

21

For max cooling on ground or during slow flight with flaps no fully retracted, the ram air doors move to the ______.

full open position (indicated by blue RAM DOOR FULL OPEN light).

22

What is the point of the ram air deflector doors?

prevent slush ingestion into ram air inlets prior to liftoff and after touchdown.

23

Ram air deflector door is dependent upon what?

state of air-ground safety sensor.

24

T/F: the pack temp control valve opens & closes in response to electronic controllers, depending on discharge flow req'd.

true.

25

T/F: With both pack controllers failed, the pack will continue to operate unless excessive temps cause the pack to trip off.

True.

26

CONT CAB refers to what?

the flight deck

27

Temperature ranges for conditioned air can be set to a range of _____

18C to 30C.

28

T/F: The zone which requires the most cooling causes both packs to produce an air temp to satisfy that zone.

True.

29

With the TRIM AIR switch in ON and one pack inop, what happens?

Zone temp control is same as two pack ops. All three individual temp settings are upheld.

30

If in single pack ops and trim air off, what happens?

the single pack tries to produce a temp that satisfies the avg temp demands of all three zones.

31

The right controller is the primary controller for what?

flight deck and forward cabin zone.

32

The left controller is the

backup controller for the flight deck and control for aft cabin zone.

33

If either the fwd or aft cabin controller fails

the trim air modulating valves close and temperature is averaged between the settings for the two zones.

34

What happens if all zone controls and primary pack controls fail?

the stby pack controls command the packs to produce air temps which will satisfy the avg temps demanded of the two cabins.

35

What happens if all temp selectors are in the OFF position?

the pack controls cause the L pack to maintain 24C and the R pack to maintain 18C as measured at the pack temp sensors.

36

What is the purpose of the RECIRC FAN?

to reduce air conditioning pack loand and the engine bleed air system demand. Switch must be in AUTO to work.

37

What is the flow of air for the RECIRC FANs?

cabin and elec equip bay to fwd cargo bay where it is filtered and sent to mix manifold.

38

In flight, when do the RECIRC FANs not operate both at a time?

If either pack is in HIGH, the left fan does not operate while the the right fan does not operate if both pack in HIGH.

39

If on the ground and both packs high, which RECIRC FAN operates?

right fan continues to operate and left shuts down.

40

The equipment coolings system cools what?

electronic equipment in the flight deck and the E&E bay.

41

T/F: the equipment cooling system has both alternate and normal supply and exhaust fans?

True

42

Equipment cooling system: __________ fans are on the aircraft ceiling while ________fans are located underneath.

supply, exhaust.

43

T/F: Some heating for the forward cargo compartment comes from the cabin air through the recirculation fan system which is then directed through the compartment lining.

True.

44

Heat for the Fwd Cargo compartment is also supplied from the equipment cooling system provided what?

the overboard exhaust valve is closed

45

What does the OFF light mean on the EQUIP COOLING panel?

illuminates for a failure of the associated fan and resulting low air flow. Can also mean a pressurization problem so check pressurization.

46

How can you reduce the load on a pack with the zone switches?

Move to a warmer setting.

47

If both PACK lights are on, what might happen?

May indicate both pack valves have closed and it could result in a gradual loss of cabin pressure and eventually a CABIN ALTITUDE warning. Descent must be made to the higher of 10,000 feet or the lowest safe altitude.

48

If at level off at lower altitude after dual PACK failure what can happen?

Temperatures may rise quickly. Speed should be kept at or above 290 kts.

49

Oxygen must be donned above what altitude?

10,000 feet.

50

What can improve ventilation after dual PACK failure?

opening the outflow valves. You must select the switch to MAN.

51

What is the proper position for the L and R RECIRC FANS with dual PACK lights and outflow valve in full open?

R RECIRC FAN = AUTO
L RECIRC FAN = OFF