787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Air Systems -
Air Conditioning System
Description
Copyright © The Boeing Company. See title page for details.
D615Z003-TBC 2.20.11
• smoke is detected in the aft equipment cooling system or aft equipment
ventilation system, or
• the AFT CARGO FIRE ARM switch is ARMED
In the override mode, the aft cargo heat and overboard exhaust valves are closed,
the vent fan and both supply fans are commanded off, and the forward equipment
cooling override valve is commanded to the override position.
Cabin differential pressure draws air through the aft E/E equipment racks to create
a reverse flow of air across the equipment, then exits through the override valve
to an overboard venturi.
In flight, the AFT EQUIP COOLING switch in OVRD aids smoke evacuation
from the passenger cabin.
On the ground, the EICAS advisory message EQUIP COOLING AFT is displayed
and the ground crew call horn in the wheel well sounds if the aft equipment
cooling system is inoperative.
The lavatory/galley ventilation system provides ventilating air for the lavatories
and galleys and smoke control for lavatories and optional crew rests. The system
is also a secondary heat sink for the Power Electronics Cooling System (PECS).
Power Electronics Cooling System
The Power Electronics Cooling System (PECS) is a liquid cooling system for the
large motor power distribution system located in the aft E/E equipment
compartment. It also provides liquid cooling to the supplemental cooling units and
associated motor controllers of the Integrated Cooling System. The system
consists of two independent liquid cooling loops. Each loop has a single pump
package which contains two fully redundant pumps. (Refer to Large Motor Power
Distribution System in Chapter 6, Section 20, for additional information.)
[Option – English / Metric units]
Liquid quantities and status for each PECS (liquid cooling) loop are displayed on
the STATUS page. PECS controls the liquid coolant supply temperature of each
loop to 85º F / 29º C during normal operation.
There is no flight deck control for the liquid cooling system. The system operation
is completely automated and no crew action is required for either normal or
non-normal modes of operation.
CAUTION: The Power Electronic Cooling System (PECS) requires a
cool-down period following pack and hydraulic EMP
shutdown to dissipate residual heat from the liquid cooled
LRUs. This prevents damaging the units and degrading the
coolant.
February 15, 2010
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