Equipment Cooling
The equipment cooling system cools electronic equipment in the flight deck and the E & E
bay. The equipment cooling system consists of a supply duct and an exhaust duct. Each
duct has a normal fan and an alternate fan. The supply duct supplies cool air to the flight
deck displays and electronic equipment in the E & E bay. The exhaust duct collects and
discards warm air from the flight deck displays, the overhead and aft electronic panels,
circuit breaker panels in the flight deck, and electronic equipment in the E & E bay.
Loss of airflow due to failure of an equipment cooling fan results in illumination of the
related equipment cooling OFF light. Selecting the alternate fan should restore airflow and
extinguish the OFF light within approximately 5 seconds. If an overtemperature occurs on
the ground, alerting is provided through the crew call horn in the nose wheel well.
Forward Cargo Compartment
The recirculation fan system circulates air from the passenger cabin around the lining of
the forward cargo compartment. When the overboard exhaust valve is closed, exhaust air
from the equipment cooling system is also diffused to the lining of the forward cargo
compartment for additional inflight heating.
