*
Fan relay energized.

A switch in the fan supplies an overheat indication to the right ECSMC. The ECSMCs contain fault logic for the fan. The ECSMCs give fault data to AIMS. AIMS shows the status message, CARGO VENT FAN BULK if the bulk cargo ventilation fan fails.
Bulk Cargo Ventilation Fan Inhibits
These conditions inhibit the fan on signal to the bulk cargo ventilation fan:
* Fan overheat
*
Aft cargo fire arm

*
Equipment cooling switch in the OVRD position

*
Bulk cargo heat switch off or low.

The fan stops when the equipment cooling switch is set to OVRD. This makes sure smoke from the passenger cabin area does not go into the bulk cargo area. If smoke from the passenger cabin goes into the bulk cargo area, it will cause the aft cargo smoke detector to turn on the flight deck effects for an aft cargo fire.
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A/C -VENTILATION -BULK CARGO VENTILATION -FUNCTIONAL DESCRIPTION

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AIR CONDITIONING -VENTILATION -LAVATORY GALLEY VENTILATION FANS, INLET DUCT AND SCREEN

Purpose
The lavatory galley ventilation fans pull air from the lavatories and galleys in the passenger cabin. A single ventilation duct (not shown) above the ceiling connects the lavatories and galleys to the fans. The fans are aft of the bulk cargo compartment end wall. Hoses (not shown) from the ventilation duct pull air across the zone temperature sensors in these areas:
*
Passenger cabin

*
Aft and bulk cargo compartments

*
Flight deck.

Lavatory Galley Ventilation Fans
The lavatory galley ventilation fans are aft of the bulk cargo compartment endwall. The fans pull air from the lavatories and galleys. The fans have these components:
*
Fan rotation arrow

*
Flow direction arrow

*
Stator housing assembly and check valve

*
Electrical connector

*
Inlet housing assembly.

Inlet Duct and Screen
There is an inlet duct and screen on the aft side of the two lavatory galley ventilation fans. The screen prevents unwanted material from going through the lavatory galley ventilation fans.
Training Information Point
The lavatory galley ventilation fans are interchangeable with the lower recirculation fans and the chiller boost fan.
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AIR CONDITIONING -VENTILATION -LAVATORY GALLEY VENTILATION FANS, INLET DUCT AND SCREEN

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AIR CONDITIONING -VENTILATION -GALLEY VENTILATION FILTERS

Purpose
The galley ventilation filters remove particles from the galley air before the air goes into the ventilation duct. The air then moves through the ventilation duct to the lavatory galley ventilation fans.
Location
Each ventilation inlet at the galleys has a ventilation filter.
Training Information Point
Galley ventilation filters are line replaceable. Remove the lens assembly and the retainer to remove the filter.
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AIR CONDITIONING -VENTILATION -GALLEY VENTILATION FILTERS

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777 AIRCRAFT MAINTENANCE MANUAL

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AIR CONDITIONING -VENTILATION -LAVATORY GALLEY VENTILATION -FUNCTIONAL DESCRIPTION

General
The environmental control system miscellaneous cards (ECSMCs) in the system card files control the lavatory galley ventilation fans. One control card at a time controls the two fans. On power up, the right card controls the fans. The left card is the backup. Each time the airplane goes from air to ground, the card in control changes. The card in control sends a fan on signal to the related power management panel. If there is no load shed condition, a switch in the electrical load management system (ELMS) electronics (ELEX) unit supplies a ground to energize the lav/galley fan relay. The relay connects power to the fan.
Only one of the two fans operate at a time. The right fan is primary and the left fan is the backup. Each time the airplane gets power, the ECSMC that is in control (usually the right ECSMC) does a test of the left fan. The right fan goes off and the left fan comes on for 20 seconds. At the end of the test of the left fan, it goes off and the right fan comes on and is tested.
　
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