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20 Cards in this Set
- Front
- Back
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3 functions of the APU control unit |
-Fuel control -Load compressor IGV control -Surge control -2 analogue and 15 digital varieties of protective shut down -Load prioritisation -Built in testing |
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When is a monitor Bite test carried out on the APU control unit |
Performed continuously after the prestart BITE test |
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When will a 90 second cool down period be required |
When the APU is Shut off with bleed air running |
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What are the 10 digital shut down |
-Over speed -Fire -Ignition failure -Shut down circuit failure -Slow start -Loss of DC power -Control Unit Failure -High oil temperature -Intake door -No acceleration |
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How to reset the system post protective shut down |
Cycle the start switch |
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Flight deck indication of a protection Shut down |
EICAS msg: APU FAULT FAULT light come on |
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How is a normal shut down carried out |
By injecting a 109% test speed signal to the overspeed Shut down circuit |
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What is the APU RPM during the start cycle when the start motor is de-energised |
50% |
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How to gain access to the APU plenum chamber |
Through a panel in the APU compartment FWD bulkhead |
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What type of compressor does the APU have |
A 2 stage centrifugal compressor |
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What are the 3 major modules of the APU |
Power section Load compressor Accessory GB |
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Purpose of the De-oiling solenoid |
To reduce viscous drag during cold starts |
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Feature of the APU generator oil system that will carry out a protection shut down |
A differential pressure switch |
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Purpose of pressurising the power section GB with compressor bleed air |
To prevent oil vapour entering the GB system |
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What divides fuel between the primary and secondary fuel nozzles |
The fuel divider |
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What operating mode would cause the IGV to be full open |
During Main engine start (MES) -In flight (INFLT) |
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Situations that will cause the IGV to modulate to full closed regardless of pneumatic mode |
High EGT |
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The IGVs are spring loaded to what position |
Closed |
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What provides a hydraulic pressure source for the IGVs |
FUEL |
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The surge control valve is spring loaded to what position |
Open |
