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16 Cards in this Set
- Front
- Back
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Where are most APUs located in modern jet transport aircraft? |
In the tail cone of the fuselage
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What is the function of an APU? |
Provides electric power and compressed air when the main engines are not operating |
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What are two sources of compressed air from an APU? |
From bleed air from the APU turbine compressor, or from a load compressor |
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Where in maintenance info based on the ATA–100 system would you find instructions for inspecting and servicing the engine of an airborne APU? |
In section 49 20 |
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How is most of the troubleshooting done for modern APUs?
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Fault codes generated by the FADEC |
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What ensures that a APU will not be shut down while it is too hot?
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An automatic time–delay in FADEC that closes the bleed air valve, reducing the APU temp and load before shutdown |
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What prevents the APU exceeding its safe operating limits when the bleed air valve is wide open? |
FADEC monitors the APUs load and regulates its fuel supply |
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What document would you use to find the safety procedures to follow when replacing an igniter plug in an APU engine?
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Maintenance manual for the APU |
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What places the greatest load on an APU? |
Bleed air loads |
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What is used to start an APU? |
Its own electric starter and battery power |
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Name two uses for the pneumatic power produced by an APU. |
Engine starting Air conditioning while on the ground |
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What kind of operating practices could cause heat shock and internal damage to an APU? |
An ubrupt shutdown of the APU while under a heavy load |
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What powers the inlet guide vanes to regulate the compressor intake airflow in some APUs? |
Fuel pressure |
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What is the typical cool down period for an APU? |
3 minutes |
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At what speed does an APU operate? |
The APU will operate near its rated RPM at all times regardless of the load demands. |
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Where does an APU get its fuel from? |
One of the aircrafts main tanks |
