C.  
The reservoir drain valve is a manually operated valve installed in the bottom of the reservoir. The fluid sampling valve is installed to permit fluid samples to be removed from the reservoir.

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 D.  There is a standpipe at the bottom of the reservoir. The fluid is taken from the standpipe to supply the EDP and the auxiliary pump. And the demand pump takes the fluid from the bottom of the reservoir. Because of the standpipe, the quantities of fluid in reservior not accessible to indication (the fluid level in EICAS reading is zero) are 1.12 gallons for system 1 and 4 and 0.74 gallons for system 2 and 3.
 5.  Hydraulic Fluid Filters
_______________________
 A.  Hydraulic fluid filters are installed in the pressure filter module, the case drain module, the return module, the auxiliary pump case drain line, and the thrust reverser return module.
 (1)  
The pressure filter module has two non-bypass filters. The EDP, demand pump, auxiliary pump, and ground cart fluid output is put through these filters.

 (2)  
The case drain module has two non-bypass filters. One filter is used for the EDP case drain flow. The other filter is used for the demand pump case drain flow.

 (3)  
The return module has one bypass filter. The filter bypass relief valve opens at approximately 350 psi. Most of the returning hydraulic fluid is put through this filter. Fluid that goes through the system pressure relief valve and the thrust reverser return fluid is not put through this filter.

 (4)  
The auxiliary pumps on systems No. 1 and No. 4 have a non-bypass filter that can be cleaned. Fluid from the case drain line is put through the filter.

 (5)  
The thrust reverser return module has a filter that can not be cleaned. Fluid that goes around the return module between the engine thrust reverser return and the hydraulic reservoir is put through this filter.

 6.  Hydraulic Supply Shutoff Valve
______________________________
 A.  The hydraulic supply shutoff valve is installed in the EDP supply line in the strut. It will stop the flow of hydraulic fluid to the engine if there is a fire. The valve will move to the closed position when the fire handle is pulled. The shutoff valve is a gate type valve. A 28 volt dc motor supplies power to operate the valve.
 7.  Heat Exchanger
______________
 A.  Each system has a fluid/fuel heat exchanger installed in the inboard aft corner of the four main fuel tanks. The heat exchanger decreases the temperature of the pump case drain fluid before it goes into the system reservoir. Heat will transmit from the fluid to the fuel in the heat exchanger. It is a coiled tube assembly having approximately 35 feet
 (10.6 m) of 1/2 inch (12.7 mm) coiled aluminum tubing.
 8.  Pressure Module
_______________
 A.  The pressure module is installed between the demand pump and the reservoir in each strut. The hydraulic system pressure sources that are available (EDP, demand pump, auxiliary pump, and/or ground service chart) are connected at the pressure module. The module has two filters with the same differential pressure indicator, four check valves, two pump pressure switches, a pressure relief valve, and a ground quick disconnect coupling.
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 B.  All of the hydraulic pressure fluid is put through the filters. The pressure relief valve opens when the system pressure increases to 3,500 psi.
 9.  Return Module
_____________
 A.  The return module is installed aft of the reservoir in the strut for systems No. 1 and No. 4. It is installed in the wing landing gear wheel wells for systems No. 2 and No. 3. Hydraulic fluid that goes to the reservoir is put through a filter in the return module. This does not include pressure relief fluid or thrust reverser return fluid.
　
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