Packs, Ram Air System, Recirc Fan and Air Flow are covered in the Bleed
Air Module.
Zone Temperature Control
There are three zones: flight deck, forward cabin and aft cabin. Desired zone
temperature is set by adjusting the individual Temperature Selectors. The selector
range is approximately 65°F (18°C) to 85°F (30°C).
The packs produce an air temperature that satisfies the zone which requires the
most cooling. Zone temperature is controlled by introducing the proper amount of
trim air to the zone supply ducts. The quantity of trim air is regulated by individual
trim air modulating valves.
During single pack operation with the TRIM AIR selected ON, zone temperature
is controlled the same as during two pack operation. During single pack operation
with the TRIM AIR selected OFF, the pack attempts to produce an air temperature
to satisfy the average temperature demands of all three zones.
If air in a zone supply duct overheats, the associated amber ZONE TEMP light
illuminates, and the associated trim air modulating valve closes. The trim air
modulating valve may be reopened after the duct has cooled by pushing the TRIP
RESET Switch.
Zone Temperature Control Modes
The left electronic controller controls the aft cabin zone and provides backup
control for the flight deck. The right controller controls the forward cabin zone and
provides primary control for the flight deck.
Failure of the primary flight deck temperature control will cause an automatic
switch to the back up control and will illuminate the CONT CAB amber ZONE
TEMP light upon Master Caution Recall. Failure of both the primary and standby
controls will illuminate the lights automatically.
Failure of the forward or aft cabin temperature control will cause the associated
trim air modulating valve to close. The Temperature Selectors operate normally,
but the Temperature Selector settings of the two passenger cabin zones will be
averaged. The amber ZONE TEMP light will illuminate upon Master Caution
Recall to indicate failure of the associated zone control.
Air Module.
Zone Temperature Control
There are three zones: flight deck, forward cabin and aft cabin. Desired zone
temperature is set by adjusting the individual Temperature Selectors. The selector
range is approximately 65°F (18°C) to 85°F (30°C).
The packs produce an air temperature that satisfies the zone which requires the
most cooling. Zone temperature is controlled by introducing the proper amount of
trim air to the zone supply ducts. The quantity of trim air is regulated by individual
trim air modulating valves.
During single pack operation with the TRIM AIR selected ON, zone temperature
is controlled the same as during two pack operation. During single pack operation
with the TRIM AIR selected OFF, the pack attempts to produce an air temperature
to satisfy the average temperature demands of all three zones.
If air in a zone supply duct overheats, the associated amber ZONE TEMP light
illuminates, and the associated trim air modulating valve closes. The trim air
modulating valve may be reopened after the duct has cooled by pushing the TRIP
RESET Switch.
Zone Temperature Control Modes
The left electronic controller controls the aft cabin zone and provides backup
control for the flight deck. The right controller controls the forward cabin zone and
provides primary control for the flight deck.
Failure of the primary flight deck temperature control will cause an automatic
switch to the back up control and will illuminate the CONT CAB amber ZONE
TEMP light upon Master Caution Recall. Failure of both the primary and standby
controls will illuminate the lights automatically.
Failure of the forward or aft cabin temperature control will cause the associated
trim air modulating valve to close. The Temperature Selectors operate normally,
but the Temperature Selector settings of the two passenger cabin zones will be
averaged. The amber ZONE TEMP light will illuminate upon Master Caution
Recall to indicate failure of the associated zone control.
