REAR OUTFLOW VALVE CONTROL Switch (three-position)

DUMP - releases pressure by fully opening the aft outflow valve MAN - turns off the cabin pressure controller

• enables manual control of the aft outflow valve and the cabin differential pressure using the MAN DIFF switch

AUTO - cabin altitude is controlled using the aft outflow valve which modulates to maintain a pre-programmed cabin altitude schedule

FWD OUTFLOW VALVE ROTARY KNOB (rotary action)

CLSD - decreases the cabin altitude by closing the forward safety valve OPN - increases the cabin altitude by opening the forward safety valve

• usually set fully counterclockwise (CLSD) when in AUTO mode
• independent of rear outflow valve operation

MAN DIFF SWITCH (three-position, spring-loaded to center)

INCR - increases cabin pressure when AUTO/MAN/DUMP switch is in the MAN position DECR - decreases cabin pressure when AUTO/MAN/DUMP switch is in the MAN position

LDG ALT ROTARY SWITCH (rotary action)

• selects the field elevation for take-off and landing as shown on the LDG ALT indicator

LDG ALT Indicator

• displays the landing altitude selected with the LDG ALT rotary switch

FAULT ANNUNCIATOR LIGHT (amber)

• on continuously when the cabin pressure control system detects a fault
• on momentarily during the power-up test mode