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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
APU overtemp?
APU automatically shuts down on the ground
25
APU fault caution?
APU shuts down automatically on the ground
26
Test APU high oil temperature
AP will shut down on the ground only
27
Apu inlet door located?
Upper rt side if fuselage
28
Minimum ambient temperature for starting?
-40c
29
How many starts in one hour?
Three starts or start attempts in any hour
30
What is the primary purpose of the APU?
Electrical power
31
The APU door is controlled by the?
ECU
32
Where is the exhaust air mixture vented??
Through the centered tail pipe
33
What is the APU and main battery voltage required before we start the APU?
22V
34
How does the APU start sequence differ in the air from on the ground?
In-flight...The APU door will not open until the start stop button is selected
35
Three ways an APU compressor stall or surge is prevented?
One way check valve in pneumatic ducting Surge control valve Control logic of the ACSCs (Interlock protection)
36
When will the APU LCV close?
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
Fuel is supplied to a FCU (fuel control unit) from???
Left collector tank Via deficated APU fuel pump
38
What monitors flow of fuel to apu?
FCU Fuel control unit ( in response to commands from ECU)
39
Appch bit ldg
Ldg gear dwn Or Flaps greater then 20
40
Appch bit takeoff
TL out of toga And Ldg gear up And Flaps 20 or less
41
APU door position in-flight depends on...
Mach number WOW Altitude
42
Apu door positionis dependent on?
Wow Mach Apu rpm
43
Apu door will automatically close when?
During shutdown And FIRE
44
B4 starting apu .. bat voltage?
22v Both main and apu
45
When does the AVAIL light turn on
99% RPM +2 seconds
46
What prevents compressor style or surge
One way check valve Surge control valve Control logic of the ACSCs
47
When start stop switch light is pressed( during shutdown) what happens?
An over speed situation is simulated in the APU shut down
48
APU GEN OFF CAUTION?
Apu ready for loading and gen switch off ( after 30 seconds)
49
Apu can never | be used for icing
Bleed misconfig
50
Apu door in flight vs on ground?
In flight .. apu door will not open until .. Start/stop is selected
51
APU Altitude starting a limit
37000
52
When does the green avail switch light illuminate green?
99% RPM plus2/ seconds
53
What three things prevent APU compressor stall
One way check valve Surge control valve Control logic of the ACSCs
54
46% 60% 95% 99% + two seconds
Started deactivated on the ground Starter deactivated in-flight Ignition turned off Ready for loading
55
APU Shuts down on the ground
OVERTEMP LO OIL PRESSURE HI OIL TEMP*
56
ECU Is off of what bus?
BATT BUS
57
APU start Inflight?
Can restart, rpm blo 12%
58
APU flameout?
Auto relight function of the ECU
59
The APU is started from which battery?
The APU battery

Crj 900 (45 decks)

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