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31 Cards in this Set
- Front
- Back
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Where is the APU located |
Section 48 |
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What are the limits for electrical and pneumatic supply from APU |
Electrical 42000ft Pneumatic 19000ft |
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What are the functions of the APU control unit |
Fuel control Load compressor IGV control Surge control Protective shut down Load prioritisation Bite |
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What are the bite routines of APU control unit |
Pre start bite Monitor bite Self test bite |
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When is the monitor bite carried out |
Continuously when APU running |
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Name the analog shutdown systems |
Over speed 107% EGT overtemp 661c |
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Name some digital shut down conditions |
Fire Over speed 109% EGT overtemp High oil temp Low oil ox Slow start Ignition failure Reverse airflow Loss of dc power |
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What are the indications for protective shutdown |
EICAS APU FAULT message and fault light |
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How is shutdown accomplished |
Over speed shutdown circuit |
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What are the 3 major modules of APU |
Power section Load compressor Accessory gearbox |
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What is driven off the accessory gearbox |
Oil pumps Fuel pump and FCU Cooling fan Starter motor Ac generator |
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How can you access the plenum chamber |
Panel in APU compartment forward bulkhead |
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Other than exhaust gas what else is ducted out through the exhaust |
Unwanted bleed air |
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What is included in the APU vent and drain system to allow monitoring of components |
Inspection caps |
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What is included in start control |
Timed acceleration Speed sequencing Ultimate temp trim |
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What are the significant speed switch points |
7% fuel and ignition on 50% starter dropout 95% load available and ignition off |
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How is EGT temp measured |
Four individual chrome alumel thermocouples |
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What is included in the oil pump |
Px pump Px regulator valve Px relief valve Filter Scavenge pump |
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What is the purpose of the de oiling valve |
Introduce air into the oil pump when oil temp is below 25f to limit viscous drag during start |
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When is the oil cooler bypassed |
When oil temp is below 176f |
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What will happen if Px differential across the generator scavenge system filter exceed 35 psi when oil temp is above 115f |
Protective shutdown |
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Why is the gearbox pressurised |
Ensure there are no oil leaks in the bleed air system |
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What is the hyd source for the load compressor inlet guide vanes |
Fuel at 250psi |
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What components make up the fuel system |
Flow divider FCU fuel nozzles |
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What does the flow divider do |
Distribute fuel to primary and secondary nozzles |
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What happens if APU shutdown is initiated with bleed air in use |
90 sec cool down period |
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What is the resting position of the IGVs |
Closed |
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What are the modes of the IGV |
Idle Duct Px ECS Main engine start Inflight |
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When are the IGV full closed and full open |
Full closed at idle Full open at main engine start & in flight |
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What is the normal position of the surge control valve |
Open |
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What will high EGT CAUSE THE IGVs to do |
Modulate closed |
