R  EFF : 001-049, 101-105, 107-107, 151-199, 49-52-00Page 4 201-210, Config-2 Aug 01/05
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 ACCESSORY COOLING - DESCRIPTION AND OPERATION
_____________________________________________
 1.
 General

_______ The accessory cooling system operates independently of the APU load compressor and the bleed and surge-air system. A cooling fan supplies sufficient cooling air to the oil cooler to keep the lubricating oil in the correct temperature range. It also supplies cooling air to the APU compartment to remove the heat which comes from the APU surface. The cooling fan is of the one-stage axial-flow type and the accessory drive gearbox turns the cooling fan rotor. The compartment cooling air flows through an outlet and through the compartment cooling valve (if installed) into the APU compartment.

 2.
 Component Location

__________________
 (Ref. Fig. 001)

 -------------------------------------------------------------------------------FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA | | | | DOOR | REF.
 -------------------------------------------------------------------------------FAN/GENERATOR - COOLING/POWER SUPPLY 316 316AR 49-52-51 VALVE - COMPARTMENT COOLING (if 316 316AR 49-52-54 installed) DUCT - OIL COOLER OUTLET 315 315AL 49-52-41
 3. System Description
__________________ (Ref. Fig. 002, 003) The accessory cooling system suppies air circulation for the oil cooler and for the ventilation of the APU compartment. The accessory cooling system has the subsequent components:
 -
a fan inlet duct,

 -
a cooling fan,

 -
a fan outlet duct,

 -
an oil cooler,

 -
an oil cooler exhaust duct,

 -
a compartment cooling valve (if installed)

 A.
 Cooling Fan

 (1) The cooling fan takes the air from the APU inlet plenum chamber. It supplies this air to the oil cooler (Ref. 49-91-00) and to the APU compartment.

 AIr System - Component Location
 Figure 001

 CES

 Air Cooling and Ventilation - Schematic
 Figure 002

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 Cooling Fan Figure 003 
R  EFF :  106-106, 108-149, 211-299, 301-399,  Page 449-52-00 Config-3 Aug 01/05
 CES 

 (2)
 The cooling fan takes the air from the APU inlet plenum chamber by suction. The air flows through the cooling fan inlet-duct to the cooling fan. The cooling fan is of the one-stage axial-flow type. It gets mechanical energy from the accessory drive gearbox and uses this energy to make the cooling air flow. A V-clamp attaches the cooling fan to the accessory drive gearbox. The gearshaft assembly of the cooling fan assembly engages with the fan drive gear of the gearbox. In the cooling fan there is a Permanent Magnet Generator (PMG) installed, which supplies direct current voltage to the ECB. This used as an emergency power supply for the ECB.

 (3)
 The air flows into the cooling fan outlet-duct. Some of the cooling air flows through the outlet and the compartment cooling valve (if installed) into the APU compartment. The remaining cooling air flows through the oil-cooler inlet duct to the oil cooler.

 B. Oil-Cooler Cooling Air
 (1)
 The cooling air flows from the cooling fan through the oil cooler inlet duct to the oil cooler. The cooling air which flows through the oil cooler keeps the oil in the correct temperature range. The oil cooler is of the heat exchanger type (Ref. 49-91-00). The cooling fan supplies sufficient air to keep the oil at the correct temperature during all operational conditions of the APU. The hot air then flows through the oil cooler outlet duct into the ambient air.

 (2)
 Bellows connect the oil-cooler outlet duct to the cooling-air outlet opening of the oil cooler. The oil-cooler outlet duct stops at the inner surface of the left access door 315AL of the APU compartment. There is an outlet in the access door. A seal at the duct end makes a flexible joint between the oil-cooler outlet duct and the access door. The seal absorbs vibrations and makes allowance for installation tolerances.

 C. APU Compartment Cooling Air Cooling air flows through the outlet and the compartment cooling valve (if installed) into the APU compartment. A drain is installed in the left access door 315AL of the APU compartment. Air and fluids, which can collect in the APU compartment, flow out through the drain. A louvered overpressure release-door is installed in the structure on the top left side of the APU compartment. It is installed between FR83 and FR85. The louvers open the APU compartment to the ambient air.

 During APU operation, the cooling air which is supplied into the APU compartment flows through the louvers into the ambient air. When the APU does not operate, the louvers permit convection to make a flow of air in the compartment.
　
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