Term
| How does the APU interlock protection system protect the APU when the left 10th stage bleed air valve is selected open while the APU LCV is open? |
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Definition
| The APU LCV will automatically close when the 10th stage bleed is selected open |
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Term
| When APU electrical and bleed air demands cause an excessive increase in EGT, what automatically occurs? |
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Definition
| APU bleed air loads are reduced by the auto modulating APU LCV |
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Term
| Why is the maximum operating altitude of 20,000 ft recommended for the APU? |
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Definition
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Term
Which of the following does not auto shutdown the APU in flight?
APU Fire detection
APU overspeed
Loss of EGT signal
Starter engaged for more than 60 seconds |
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Definition
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Term
| What prevents the APU compressor from surging? |
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Definition
| APU VGD (variable geometry diffuser) |
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Term
| How can the APU be shut down |
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Definition
| APU fire button, power fuel button, start stop button, apu shutoff button on external service panel, apu shutoff button in aft equipment bay. |
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Term
| When the APU PWR/FUEL switchlight is selected during start, does the starter engage? |
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Definition
| No, the starter engages when you select start stop switchlight. It activates for 60 seconds or until the APU is 50%rpm or higher |
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Term
| How does a pilot know when the shutdown APU BITE test is complete? |
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Definition
| The APU gauges are removed from ED2 |
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Term
| If the APU door position is unknown by the APU ECU, what indication is displayed on ED2? |
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Definition
| APU DOOR with white dashes |
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Term
| What time limit does AWAC observe after APU start before selecting the APU LCV open? |
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Definition
| 2 minutes. It allows for the LCV to equalize temperature with the hot APU gasses so it dont crack. |
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Term
| If the XFLOW/APU pump has failed, is there another method for delivering fuel to the APU when the engines are shutdown? |
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Definition
| Yes, using both the APU negative gravity relief valve and the boost pumps are turned on |
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Term
| Which computer controls the function of the APU |
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Definition
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Term
| What minimum APU and MAIN battery voltage is required to start the APU? |
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Definition
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Term
| What is the purpose of the APU titanium enclosure? |
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Definition
| Contain an APU fire so it dont spread into the Aft equipment bay and destroy the airplane. |
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Term
| When is the APU door displayed |
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Definition
| When the APU PWR/FUEL button is selected |
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Term
| What is the minimum time required to wait after APU shutdown before the APU start can be attempted? |
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Definition
| 60 seconds because thats how long it takes to complete the shutdown BITE test |
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Term
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Definition
| Using an air / oil heat exchanger and an accessory gearbox mounted fan (intake on the left side under eng cowling) |
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Term
| What is the primary purpose of the APU? |
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Definition
| Provide AC electric power (30kVA generator) |
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Term
| Why does AWAC recommend rapid selection of the APU PWR/Fuel and START/STOP switchlights in flight? |
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Definition
| to get the ignition sequence started before the ram air causes the RPMs to get to high |
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Term
| What does the green AVAIL light on the APU START/STOP switchlight indicate? |
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Definition
| APU AC power is available |
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Term
| At what RPM does the APU starter disengage during the start sequence? |
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Definition
| at 50% rpm or after 60 seconds which ever is first |
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Term
| What is the maximum operating altitude of the APU? |
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Definition
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