787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Air Systems Chapter 2
Air Conditioning System Description Section 20
Copyright © The Boeing Company. See title page for details.
D615Z003-TBC 2.20.1
2.20 Air Systems-Air Conditioning System Description
Air Systems20 Air Con ditioning System Descriptio nAir Conditioning Syste m Description
Introduction
The air conditioning system supplies conditioned outside air and recirculated
cabin air at a controlled temperature throughout the airplane.
The system supplies conditioned air to the flight deck shoulder heaters.
The system supplies ventilation for the passenger cabin:
• lavatories
•galleys
[Option – Crew rest]
• overhead crew rest compartments
Pack control, zone temperature control, cabin air recirculation, fault detection, and
overheat protection are all automatic. Backup system control modes operate
automatically in the event of system failures.
The airplane is divided into seven temperature zones: the flight deck and six
passenger cabin zones.
Note: Zones A and B contain sub-zones A1 and B1 that are not depicted on the
air synoptic.
Air Conditioning Packs
[Option – English / Metric units]
Outside air is supplied to four electric cabin air compressors (CAC) through two
dedicated inlets located in the wing to body fairings. During normal ground
operations and landing phases of flight, deflector doors deploy in front of the CAC
inlets to prevent debris from entering the CACs. These deflector doors may retract
on the ground when ambient air temperature is below 35°F / 2°C or above 95°F /
35°C.
The air is then pressurized and flow-regulated by the CACs and supplied to two
identical air conditioning packs. Two CACs are dedicated to each pack. A single
CAC provides sufficient air to operate its associated pack in all operating modes.
Packs are controlled by two identical pack control systems. If one system fails,
pack control automatically switches to the other system.
Air flow to the packs is controlled by regulating the cabin air compressors. CAC
output is increased automatically during high demand periods (to compensate for
a failed pack), or is limited during electrical load shed conditions to ensure
sufficient electrical power is available to other critical systems. During normal
operation, outside airflow is controlled to ensure that a minimum ventilation rate
is maintained.
February 15, 2010
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