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46 Cards in this Set
- Front
- Back
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State the component to which the bleed air control valve is attached to |
Turbine plenum |
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Maximum continuous EGT is |
680°C |
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State the 4 sections of the APU |
Compressor section Turbine section Accessories section Exhaust section |
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Where does the scavenge pump receive its oil from? |
Turbine cavity and accessory drive assy |
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State the purpose of the low oil pressure switch |
Prevents APU intake door from closing during shutdown until APU speed has dropped and compressor is no longer drawing air through the intake <20psi allows door to close >26psi prevents door from closing |
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The APU oil tank has a capacity of 6 U.S quarts |
False. 4 U.S quarts |
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State the purpose of the cooling fan within the lubrication system |
Draws air in through the air intake duct and forces air through the oil cooler |
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State the location of the ‘O’ valve |
In #2 dry bay |
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What is the purpose of the fuel strainer? |
Provide an initial fuel filter process and low point water drain |
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State the function of the acceleration limiter? |
To schedule fuel flow during start and acceleration to on-speed RPM |
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The fuel shutoff solenoid valve is located in No. 2 dry bay. True or false? |
False. Lower outboard side of APU |
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What is the component that is mounted to the top of the combustion cap? |
Fuel atomizer Duplex 4psi primary 75psi secondary |
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State the location of the plenum drain valve |
Bottom of the turbine plenum |
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What type of power is required to operate the APU starter motor? |
28VDC |
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What is the function of the fuel holding relay? |
Energises the fuel shut off valve (O-valve) when the APU is above 50% RPM |
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The FHR energises the fuel shutoff valve (O-valve) when the APU is above 98%. True or false? |
False |
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Which component is used in conjunction with EGT to modulate the load control valve? |
Proportional control valve |
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State the function of the air pressure regulator |
To regulate compressor discharge pressure (CDP) for operating the bleed air control valve |
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Bleed air is only available above 98% RPM. True or false? |
False. 95% RPM |
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The E3SS contains 3 micro switches that are set at what RPM’s? |
50% - start sequence 95% - ignition circuit de-energises 110% - fuel SOV |
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What type of compressor is used on the APU? |
Two-stage centrifugal compressor |
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What 4 major sections make up the APU? |
Compressor Turbine Accessories Exhaust |
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What 4 major sections make up the APU? |
Compressor Turbine Accessories Exhaust |
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What is the purpose of the APU low oil pressure switch? |
Prevents the APU intake door from closing during shutdown until APU speed has dropped and compressor is no longer drawing air through the intake |
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What is the purpose of the APU oil pressure sequencing switch? |
Energises the fuel shut-off solenoid valve and ignition when the APU is rotating at a sufficient speed |
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What pressure will the pressure regulator in the oil pump maintain? |
100 +/- 10psi |
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Where does the APU receive its fuel from? |
Gravity fed from #2 tank |
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Where does the APU receive its fuel from? |
Gravity fed from #2 tank |
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What component controls the PVC? |
Electronically controlled by the electronic temperature and acceleration control (ETAC) |
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How does the PVC work during start? |
Energised full closed on start up ETAC signals PVC to open if EGT exceeds limits |
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When will the fuel solenoid shutoff valve energise? |
Energised open when oil pressure is greater than 4 psi ( approx 10% RPM ) |
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What is the purpose of the APU fuel governor? |
To control fuel flow to the atomiser during on-speed operation ( > 95% RPM ) |
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When will the fuel governor take over from the acceleration limiter? |
>95% RPM |
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What components within the APU start system are interchangeable? |
Aux start relay, fuel holding relay |
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What does the aux star relay control power to? |
The starter |
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When does APU ignition occur? |
When oil pressure => 4 psi Continues until 95% rpm Power cut-off from ignition curcuit |
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When will the power to the APU starter be removed? |
50% rpm |
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What component energises the fuel solenoid shutoff valve above 50% rpm |
Fuel holding relay (FHR) |
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Where is bleed air tapped off from the APU? |
Turbine plenum via load control valve |
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What pressure is CDP for operation of the load control valve regulated to? |
19.5psi |
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Which sensors does the ETAC use to maintain an EGT schedule during bleed air on operations? |
T2 sensor |
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When is bleed air able to be selected on? |
APU rpm >95% |
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When is bleed air able to be selected on? |
APU rpm >95% |
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During bleed air on operations what temperature will the ETAC maintain EGT below? |
680°C |
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The E3SS provides electrical sequencing of the APU at what speeds? |
50% rpm 95% rpm 110% rpm |
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At what % rpm will the APU shutdown due to an overspeed? |
110 |
