DOC AIRBUS | AMM A320FENGINE BEARING COOLING - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
1. Component Location
** ON A/C NOT FOR ALL 
Air System (Buffer Air Heat Exchanger)- The buffer air valve solenoid is located at approximately the 4 o'clock position.
- The buffer air valve pressure sensor is attached to the Compressor Intermediate Case (CIC) bulkhead at the 3 o'clock position.
- The buffer air heat exchanger is mounted on brackets attached to the diffuser case at the 11 o'clock position.
| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 4056KS | BUFFER AIR VALVE SOLENOID | 400 | 73-11-03 | ||
| 4057KS | BUFFER AIR VALVE PRESSURE SENSOR | 400 | 73-11-00 | ||
| 4100JM | BUFFER AIR HEAT EXCHANGER | 400 | 73-11-00 | ||
2. System Description
A. Engine Bearing Cooling
(1) The bearing compartments are cooled using two passive engine bearing cooling systems.
(2) Buffer/Ventilation System
(a) The main components of the buffer/ventilation system are the Low Pressure (LP) buffer shutoff valve, the LP buffer shutoff valve solenoid, the Low Pressure Compressor (LPC) check valve, the buffer air pressure sensor, the buffer air manifold, the external buffer air tubes and the internal buffer air tubes.
(b) Buffer air for the No. 1, 2, 3, 5 and 6 bearing compartments is supplied from the 3rd stage HPC and the LPC by the LP buffer shutoff valve which is controlled by the LP buffer shutoff valve solenoid.
(c) The LP buffer shutoff valve solenoid is operated by the buffer air pressure sensor.
(d) Buffer air that makes an exit from the No. 3 bearing forward seal area then flows through the Low Pressure Turbine (LPT) shaft inner diameter to the No. 5 and 6 bearing compartment.
(3) Engine Bearing Cooling System
(a) The main components of the cooling system are the buffer air heat exchanger, the external cooling air tubes and the internal buffer air tubes.
1 The No. 4 bearing compartment buffer air is supplied from the 3rd stage high compressor bleed plenum by the pneumatically controlled LP buffer shutoff valve.
2 The high compressor supply air enters the buffer air heat exchanger through external plumbing. It then flows through the air-to-air heat exchanger.
3 Cooling air is supplied to the heat exchanger from the LPC discharge air (station 2.5 air). The station 2.5 air exits the heat exchanger and dischargers into the fan bypass.
4 The cooled high compressor discharge air is then routed to the No. 4 bearing compartment by internal and external plumbing.
5 At the bearing compartment, the cooled air flows around the compartment wall of the bearing housing to cool the bearing compartment.