(e)  
If the airflow is 750 feet per minute, then the ventilation is adequate.

 (f)  
If the airflow is less than 750 feet per minute, then there is a problem with the ventilation system.

 (g)  
If there is a problem with the ventilation system, then do a check of the ventilation system as follows: 1) Make sure the hoses that connect the water separator to the

 bowl rim and tank are not blocked.
 NOTE: Most of the ventilation air flows through the
____
 bowl vent.

 2) Make sure the hose that connects the lavatory to the main
 ventilation duct is not kinked, blocked or disconnected. 3) Make sure the anti-siphon hole is not clogged. 4) Make sure the lavatory/galley vent fan operates correctly
 (AMM 21-26-00/501). 5) Make sure the main lavatory/galley ventilation duct is not broken and does not have blockage. 6) Make sure the check valve for the ventilation fan is not failed closed or failed open.
 G. Galley Ventilation Health Check
 S 715-024
 (1)  
Hold the air velocity probe 0.5 inch below the center of the galley vent grilles.

 (a)  
Make a record of the air velocity for each galley vent.

 (2)
If the velocity is 75 feet per minute, then there is adequate flow.

 S 715-026

 (3)  
If the air velocity is less than 75 feet per minute, then there is a problem with the ventilation system:

 S 715-025
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757 MAINTENANCE MANUAL
 S 215-027
 (4)  
If there is a problem with the ventilation system, then do a check of the ventilation system as follows:

 (a)  
Make sure the hose that connects the galley to the main ventilation duct is not kinked, blocked or disconnected.

 (b)  
Make sure the galley filter pad is not clogged.

 1)  If the galley filter pad is clogged, then replace the pad (AMM 21-26-03/401).

 (c)  
Make sure the lavatory/galley vent fan operates correctly (AMM 21-26-00/501).

 (d)  
Make sure the main lavatory/galley ventilation duct is not broken or have blockage.

 (e)  
Make sure the check valve for the ventilation fan is not failed closed or failed open.

 H.  
Put the Airplane Back to Its Usual Condition

 S 415-028
 (1)  
Close the access door for the main equipment center, 119BL
 (AMM 06-41-00/201).

 S 865-029

 (2)  
Remove the electrical power, if it is not necessary
 (AMM 24-22-00/201).

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757 MAINTENANCE MANUAL
 AFT EQUIPMENT VENTILATION FAN - REMOVAL AND INSTALLATION
________________________________________________________
 1.  General_______
 A.  The aft equipment ventilation fans are installed aft of the bulk cargo compartment. The fans are interchangeable. The fans operate, one at a time, to draw air through the areas that follow:
 (1)  
The lavatories

 (2)  
The galleys

 (3)  
The aft electrical equipment center.

 B.  
The No. 1 fan is inboard of the No. 2 fan.

 TASK 21-26-01-004-001
 2.  Remove the Aft Equipment Ventilation Fan (Fig. 401)________________________________________
 A.  References
 (1)  
AMM 06-46-00/201, Entry Service and Cargo Doors, Access Doors and Panels

 (2)  
AMM 25-50-03/401, Cargo Compartment Bulkhead Lining

 B.  
Access

 (1)  
Location Zones
 165 Area aft of bulk cargo compartment (Left)

 C.  
Prepare for the Removal

 S 864-002
 (1)  
　
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