DOC AIRBUS | AMM A320FACCESSORY COOLING - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
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 into the APU compartment.
** ON A/C NOT FOR ALL 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 into the APU compartment.
2. Component Location
** ON A/C NOT FOR ALL 
APU Cooling and Ventilation - Component Location| ------------------------------------------------------------------------------- |
| FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA |
| | | | | DOOR | REF. |
| ------------------------------------------------------------------------------- |
| 4005KM5 FAN - COOLING 316 316AR 49-52-51 |
3. System Description
The accessory cooling system supplies air circulation for the oil cooler and for the ventilation of the APU compartment. The accessory cooling system consists of:
The accessory cooling system supplies air circulation for the oil cooler and for the ventilation of the APU compartment. The accessory cooling system consists of:
- a cooling-fan inlet duct,
- a cooling fan,
- a cooling-fan outlet duct,
- an oil-cooler inlet duct,
- an oil cooler,
- an oil-cooler outlet duct.
A. Cooling Fan
The cooling fan takes the air from the APU inlet plenum chamber. It supplies this air to the oil cooler (Ref. AMM D/O 49-91-00-00) and to the APU compartment.
The air flows through the cooling fan inlet-duct to the cooling fan, through the fan and out to the oil cooler.
The cooling fan is of the one-stage axial-flow type. It is driven by the accessory drive gearbox and uses this power 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 cooling fan idler of the gearbox.
The cooling fan takes the air from the APU inlet plenum chamber. It supplies this air to the oil cooler (Ref. AMM D/O 49-91-00-00) and to the APU compartment.
The air flows through the cooling fan inlet-duct to the cooling fan, through the fan and out to the oil cooler.
The cooling fan is of the one-stage axial-flow type. It is driven by the accessory drive gearbox and uses this power 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 cooling fan idler of the gearbox.
B. Oil-Cooler Cooling Air
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. AMM D/O 49-91-00-00). The hot air then flows through the oil-cooler outlet duct into the ambient air.
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.
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. AMM D/O 49-91-00-00). The hot air then flows through the oil-cooler outlet duct into the ambient air.
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 into the APU compartment.
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 position of the louver prevents the ingestion of fluids and other contaminents from other aircraft zones. Any vapors that comes out of the compartment are dispersed to prevent a hazard. 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.
Cooling air flows through the outlet into the APU compartment.
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 position of the louver prevents the ingestion of fluids and other contaminents from other aircraft zones. Any vapors that comes out of the compartment are dispersed to prevent a hazard. 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.