Air Systems

Question 1

What’s the function of the CKPT/CABIN TEMP selector switches

AUTO
MANUAL

Answer 1

1. AUTO - Temperature automatically adjusts toward HOT or COLD when the selector is moved left or right of the index mark
2. MANUAL (COLD/STOP/HOT) - spring loaded to stop. In manual, momentarily moving the selector toward HOT or COLD opens or closes the temperature control valve. This is displayed on the L/R VALVE TEMP CONTROL indicator

Question 2

What’s the meaning of the blue AUTO 1 INOP and AUTO 2 INOP lights on the pressurization panel

Answer 2

INOP (2) blue - illuminates when that system fails. The standby system automatically controls pressurization

Question 3

What is the meaning of the flow light

Answer 3

FLOW Light (Amber) - illuminated with a closed outflow valve and a cabin climb rate is detected

Question 4

What is the meaning of the amber AUTO INOP light on the pressurization panel

Answer 4

Illuminated when both automatic systems fail. Pressurization is manually monitored and controlled

Question 5

What’s the function of the air conditioning shutoff switch and what can happen during taxi

OVRD
AUTO

Answer 5

1. OVRD - deactivated automatic shutdown of air conditioning packs
2. AUTO - Automatically shuts down packs if either engine fails during takeoff (cabin differential pressure of less than 1.3 psi)
3. Excessive thrust during one engine taxi may activate this automatic shutdown circuit and shut off both packs. Subsequent thrust reduction will restart the packs

Question 6

What’s the function of the L/R pneumatic X-FEED valve levers

Answer 6

Open: opens respective X-FEED valve

1. On the ground, supplies APU bleed air or air from a pneumatic ground source for operation of one or both air conditioning packs, and for engine start
2. In flight, supplies the bleed air requirements for airfoil ice protection

Closed: closes respective X-FEED valve

1. On the ground, shuts off APU bleed air or air from a pneumatic ground source used for operation of one or both air conditioning packs or for engine start
2. In flight, shuts off bleed air supply for the airfoil ice protection system and for opposite engine pneumatic starts. Air conditioning pack pneumatic supply is from its respective engine only

Question 7

What’s the function of the CABIN ALT Control wheel

Answer 7

1. When cabin alt control is selected to auto, the control wheel rotates as the cabin air outflow valve automatically adjusts to maintain cabin altitude
2. When selected to manual, the control wheel is locked in position. To adjust cabin altitude, push down on the control wheel and rotate in the desired direction. The outflow valve position indicator will indicate the position of cabin air outflow

Question 8

What’s the difference between AUTO and HP BLD OFF positions of the air conditioning L/R SUPPLY switches

Answer 8

1. HP BLD OFF - closes the augmentation valve inhibiting the utilization of high stage bleed air
2. AUTO - if the low stage pneumatic supply pressure is too low, the augmentation valve opens to supply high stage bleed air pressure

Question 9

What’s the operation of the RADIO RACK switch(3)

Answer 9

1. VENTURI - turns off radio rack fan. Opens Venturi valve
2. FAN - turns on primary radio rack fan and closes Venturi valve to cool radio rack and heat forward cargo compartment. If the primary fan fails in flight, the standby radio rack fan automatically comes on
3. On the ground, both primary and standby radio rack fans are on, and the Venturi valve is clised

Question 10

The cabin altitude is controlled manually by what

Answer 10

Moving the cabin altitude control lever down and adjusting the cabin altitude control wheel as necessary to maintain the desired cabin altitude