DOC AIRBUS | AMM A320FLOAD COMPRESSOR - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The single-stage load compressor is driven directly from the power section.
It supplies compressed air (bleed air) to the aircraft pneumatic system.
** ON A/C NOT FOR ALL The single-stage load compressor is driven directly from the power section.
It supplies compressed air (bleed air) to the aircraft pneumatic system.
2. Component Location
** ON A/C NOT FOR ALL 
Load Compressor - Component Location| ------------------------------------------------------------------------------- |
| FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA |
| | | | | DOOR | REF. |
| ------------------------------------------------------------------------------- |
| 8013KM LOAD COMPRESSOR INLET TEMP/PRESS SNSR 316 316AR 49-23-17 |
| 8012KM LOAD COMPRESSOR DISCH TEMP. SNSR 316 316AR 49-23-16 |
| 8014KM ACTUATOR - INLET GUIDE VANE 316 316AR 49-23-51 |
3. System Description
The machined titanium single-stage centrifugal impeller is attached to the single main shaft of the engine. A curvic coupling transmits the drive torque from the engine to the centrifugal impeller. An Inlet Guide Vane (IGV) assembly which has 24 vanes controls the amount of air bled from the APU load compressor. The IGV assembly is installed immediately upstream of the load compressor impeller. The IGVs are held at the outboard end and have gear segments that turn the vanes to the required position. A common ring gear engages with the gear segments to synchronize the vane position.
Pressurized fuel from the Fuel Control Unit (FCU) supplies the power to the IGV hydraulic (fuel) servo actuator. This hydraulic (fuel) servo actuator sets the position of the IGVs.
A ball bearing supports the forward end of the rotating group and is separated from the load compressor airside by a carbon seal. Because the load compressor delivers air to the cabin and various pneumatic components, this carbon seal is aided by a pressurized labyrinth seal. A drain is located between the labyrinth and carbon seal. Oil in this drain indicates a failed carbon seal. The housing of the centrifugal compressor will contain the debris if a compressor hub failure occurs.
** ON A/C NOT FOR ALL The machined titanium single-stage centrifugal impeller is attached to the single main shaft of the engine. A curvic coupling transmits the drive torque from the engine to the centrifugal impeller. An Inlet Guide Vane (IGV) assembly which has 24 vanes controls the amount of air bled from the APU load compressor. The IGV assembly is installed immediately upstream of the load compressor impeller. The IGVs are held at the outboard end and have gear segments that turn the vanes to the required position. A common ring gear engages with the gear segments to synchronize the vane position.
Pressurized fuel from the Fuel Control Unit (FCU) supplies the power to the IGV hydraulic (fuel) servo actuator. This hydraulic (fuel) servo actuator sets the position of the IGVs.
A ball bearing supports the forward end of the rotating group and is separated from the load compressor airside by a carbon seal. Because the load compressor delivers air to the cabin and various pneumatic components, this carbon seal is aided by a pressurized labyrinth seal. A drain is located between the labyrinth and carbon seal. Oil in this drain indicates a failed carbon seal. The housing of the centrifugal compressor will contain the debris if a compressor hub failure occurs.
A. Variable Inlet Guide-Vane (IGV)
The IGV assembly has 24 IGVs. They are installed radially at the load compressor inlet.
The IGV assembly has 24 IGVs. They are installed radially at the load compressor inlet.
B. The IGV Actuator
The IGV actuator is the hydromechanical servomechanism which controls the opening angle of the IGVs. To adjust the correct IGV angle, the IGV actuator moves the IGV assembly geartrain. It uses the high pressure fuel supplied from the Fuel Control Unit (FCU) (Ref. AMM D/O 49-32-00-00) as the hydraulic power source. The internal return spring ensure that the the IGV's will be held in their closed position during the APU start sequence.
The ECB monitors the IGV actuator operation.
The IGV actuator has the subsequent primary components:
The IGV actuator is the hydromechanical servomechanism which controls the opening angle of the IGVs. To adjust the correct IGV angle, the IGV actuator moves the IGV assembly geartrain. It uses the high pressure fuel supplied from the Fuel Control Unit (FCU) (Ref. AMM D/O 49-32-00-00) as the hydraulic power source. The internal return spring ensure that the the IGV's will be held in their closed position during the APU start sequence.
The ECB monitors the IGV actuator operation.
The IGV actuator has the subsequent primary components:
- the Hydraulic Actuator,
- the Electrohydraulic Servovalve (EHSV),
- the Linear Variable Differential-Transducer (LVDT).
- the Internal Return Spring
C. Load Compressor Inlet Temperature/Pressure Sensor
The load compressor inlet temperature/pressure sensor is a combined unit. It is located at the APU air intake plenum. The temperature part of the sensor measures the temperature in the air intake plenum. The sensor is a variable resistor which is fed by a constant 1mA current suppied from the ECB.
The ECB uses the sensor output voltage for the control of the fuel metering, the EGT limitation and the air flow calculation.
The pressure part of the sensor measures the air pressure in the air intake plenum. The pressure sensor is a varable resistor device.
The ECB uses the sensor output voltage for the control of the fuel metering, the EGT limitation and the air flow calculation.
The load compressor inlet temperature/pressure sensor is a combined unit. It is located at the APU air intake plenum. The temperature part of the sensor measures the temperature in the air intake plenum. The sensor is a variable resistor which is fed by a constant 1mA current suppied from the ECB.
The ECB uses the sensor output voltage for the control of the fuel metering, the EGT limitation and the air flow calculation.
The pressure part of the sensor measures the air pressure in the air intake plenum. The pressure sensor is a varable resistor device.
The ECB uses the sensor output voltage for the control of the fuel metering, the EGT limitation and the air flow calculation.
D. Load Compressor Discharge Temperature Sensor
The load compressor discharge temperature sensor is located on the APU bleed valve inlet duct. The sensor is a variable resistor which is fed by a constant 1mA current suppied from the ECB.
The ECB uses the sensor output voltage for the calculation of the air flow.
The load compressor discharge temperature sensor is located on the APU bleed valve inlet duct. The sensor is a variable resistor which is fed by a constant 1mA current suppied from the ECB.
The ECB uses the sensor output voltage for the calculation of the air flow.
5. Operation/Control and Indicating
The adjustable IGVs control the load compressor airflow (output) for the necessary input to the aircraft system (Ref. AMM D/O 49-51-00-00).
The APU maintains a closed IGV position of 72 degrees during its acceleration phase, until a check point is reached at 98 % N. After this point, the IGVs move fractionally to assume their fully closed position of 82 degrees.
The aircraft system transmits a demand signal to the Electronic Control Box (ECB) 59KD to give the necessary IGV control.
The adjustable IGVs control the load compressor airflow (output) for the necessary input to the aircraft system (Ref. AMM D/O 49-51-00-00).
The APU maintains a closed IGV position of 72 degrees during its acceleration phase, until a check point is reached at 98 % N. After this point, the IGVs move fractionally to assume their fully closed position of 82 degrees.
The aircraft system transmits a demand signal to the Electronic Control Box (ECB) 59KD to give the necessary IGV control.