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Crj 900 > APU > Flashcards

APU Flashcards

0
Q

The APU compartment is made of

A

Titanium

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1
Q

What prevents compressor surge?

A

The surge control valve

Closed below 17,000 feet

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2
Q

What controls the different of stages of the APU

A

The electronic control unit

ECU

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3
Q

What powers the ECU?

A

The PWR/FUEL switch lights on the APU Control Panel

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4
Q

Is the APU door position shown continuously?

A

YES

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5
Q

When are the RPM and EGT gauges shown on the EICAS status page

A

Upon selection of the APU PWR/FUEL switchlight

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6
Q

APU Max operating altitude

A

41,000

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7
Q

Max altitude for starting APU

A

37,000

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8
Q

Max altitude for bleed air

A

25,000

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9
Q

Ground starting altitude limit

A

15,000

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10
Q

What type of engine is the APU

A

Single shaft constant speed design

two stage turbine

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11
Q

Fuel for the APU comes from

A

The left collector tank

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12
Q

The APU gearbox has an internal oil sump

A

.

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13
Q

Where is the inlet door located

A

Upper right side of the rear fuselage

Controlled by the ECU

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14
Q

How many air inlets door positions on the ground

A

Two positions on the ground

Closed or open

In-flight it is variable

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15
Q

What does the air inlet door ram air provide air for

A

APU operation

And

Oil cooling

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16
Q

What happens when the power fuel switch light is pressed

A

APU IN BITE STATUS MSG

APU SOV STATUS MSG

RPM/EGT gauges

Door opens

APU fuel pump turns on

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17
Q

What happens when the start stop switch light is pressed

A

Starter is energized(
APU START MSG)

Ignition
Fuel introduced

Start legend on the APU panel comes on

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18
Q

The APU starter is deactivated at

A

46% on the ground

60% Inflight

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19
Q

What notifies the crew that the APU is ready for loading

A

Two seconds after the APU reaches 99%

available legend in the start stop switch light illuminates

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20
Q

When the start stop switch light is selected to stop the APU

A

The APU will automatically shed it’s loading and shut down

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21
Q

When the power fuel switch light is deselected

A

The fuel shut off valve closes

Power is removed from the ECU

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22
Q

On the ground the APU can be shut down bye

A

An emergency stop button located in the APU compartment

On APUshut off switch on the external services panel

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23
Q

APU overspeed?

A

APU shuts down automatically

Ground and flight

20-15 ch 20 Airborne auxiliary power

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24
Q

APU overtemp?

A

APU automatically shuts down on the ground

25
Q

APU fault caution?

A

APU shuts down automatically on the ground

26
Q

Test

APU high oil temperature

A

AP will shut down on the ground only

27
Q

Apu inlet door located?

A

Upper rt side if fuselage

28
Q

Minimum ambient temperature for starting?

29
Q

How many starts in one hour?

A

Three starts or start attempts in any hour

30
Q

What is the primary purpose of the APU?

A

Electrical power

31
Q

The APU door is controlled by the?

32
Q

Where is the exhaust air mixture vented??

A

Through the centered tail pipe

33
Q

What is the APU and main battery voltage required before we start the APU?

34
Q

How does the APU start sequence differ in the air from on the ground?

A

In-flight…The APU door will not open until the start stop button is selected

35
Q

Three ways an APU compressor stall or surge is prevented?

A

One way check valve in pneumatic ducting

Surge control valve

Control logic of the ACSCs
(Interlock protection)

36
Q

When will the APU LCV close?

A

Either PRSOV open

Wing or cowl engine anti-ice selected on..if APU is the bleed source

When selected to manual modeusing an engine as a bleed source

37
Q

Fuel is supplied to a FCU (fuel control unit) from???

A

Left collector tank

Via deficated APU fuel pump

38
Q

What monitors flow of fuel to apu?

A

FCU

Fuel control unit

( in response to commands from ECU)

39
Q

Appch bit ldg

A

Ldg gear dwn

Or

Flaps greater then 20

40
Q

Appch bit takeoff

A

TL out of toga

And

Ldg gear up

And

Flaps 20 or less

41
Q

APU door position in-flight depends on…

A

Mach number

WOW

Altitude

42
Q

Apu door positionis dependent on?

A

Wow

Mach

Apu rpm

43
Q

Apu door will automatically close when?

A

During shutdown

And FIRE

44
Q

B4 starting apu .. bat voltage?

A

22v

Both main and apu

45
Q

When does the AVAIL light turn on

A

99% RPM +2 seconds

46
Q

What prevents compressor style or surge

A

One way check valve

Surge
control valve

Control logic of the ACSCs

47
Q

When start stop switch light is pressed( during shutdown) what happens?

A

An over speed situation is simulated in the APU shut down

48
Q

APU GEN OFF CAUTION?

A

Apu ready for loading and gen switch off ( after 30 seconds)

49
Q

Apu can never

be used for icing

A

Bleed misconfig

50
Q

Apu door in flight vs on ground?

A

In flight .. apu door will not open until ..

Start/stop is selected

51
Q

APU Altitude starting a limit

52
Q

When does the green avail switch light illuminate green?

A

99% RPM plus2/ seconds

53
Q

What three things prevent APU compressor stall

A

One way check valve

Surge control valve

Control logic of the ACSCs

54
Q

46%

60%

95%

99% + two seconds

A

Started deactivated on the ground

Starter deactivated in-flight

Ignition turned off

Ready for loading

55
Q

APU Shuts down on the ground

A

OVERTEMP

LO OIL PRESSURE

HI OIL TEMP*

56
Q

ECU Is off of what bus?

57
Q

APU start Inflight?

A

Can restart, rpm blo 12%

58
Q

APU flameout?

A

Auto relight function of the ECU

59
Q

The APU is started from which battery?

A

The APU battery

Crj 900 (45 decks)

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