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RJET E170 Study Guide 12B > APU > Flashcards

APU Flashcards

1
Q

What kind of APU is on the aircraft?

A

Sundstrand APS 2300

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2
Q

Describe the APU

A
  • Constant speed

- Single-stage smeller with a 2-stage axial-flow turbine

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3
Q

What is the voltage and kVA of the APU?

A

115VAC, 40 kVA

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4
Q

What monitors and controls the APU?

A

Its own dedicated FADEC

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5
Q

What battery is used for the APU start?

A
  • BATT 2 powers the starter

- BATT 1 powers the FADEC and EICAS for monitoring

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6
Q

What is the fuel source for the APU when the engines are running?

A

Right fuel tank (ejector pump)

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7
Q

What fuel pump is used for APU start?

A
  • When BATTs on only: DC fuel pump
  • AC power on: AC fuel pump
  • DC power only: DC fuel pump
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8
Q

What normally provides fuel to the APU when the engine is not running?

A
  • # 2 fuel tank
  • AC power: AC fuel pump
  • DC power only: DC fuel pump
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9
Q

When does APU electrical and pneumatic loading become available?

A

3 seconds after the APU speed has reached 95%

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10
Q

Describe the APU start sequence during a ground start

A

Starter engagement, ignition at 6%, fuel after 0.5 secs and starter cutout at 50%

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11
Q

Describe the APU start sequence during an in-flight start

A

Starter engagement, ignition at 7-17%, fuel after 0.5 secs and starter cutout at 50%

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12
Q

Will the APU shutdown automatically if speed and acceleration rate isn’t reached in starting cycle time?

A

Yes

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13
Q

What indication would you have of an APU auto-shutdown?

A

An APU FAIL EICAS message

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14
Q

What does moving the APU start switch to OFF do?

A
  • Initiates normal shutdown
  • 1 min cool down
  • Pneumatics removed immediately and electrical power is removed after the 1 minute cool down
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15
Q

What happens when you rotate the APU master switch to ON?

A

Powers the FADEC and opens the APU shutoff valve

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16
Q

Can the APU shutdown be cancelled?

A

Yes, by moving the START switch back to ON before the 1 min cool down is over

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17
Q

Can the APU pneumatics be used during the cool down period?

A

No

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18
Q

Can the APU electrical power be used during the cool down period?

A

Yes

19
Q

How is the APU shutdown immediately?

A
  • APU EMER STOP button

- No 1 min cool down

20
Q

What is indicated by an illuminated red bar in the upper half of the EMER STOP button?

A

An APU fire

21
Q

What BUS provides APU fire protection>

A

DC ESS BUS 2

22
Q

What BUS provides APU fire detection?

A

DC ESS 1 and 2 (Using MAU 1 and 2). I think it may just be DC ESS BUS 1

23
Q

What happens when the APU EMERGENCY STOP button is pushed?

A

The APU fuel shutoff valve closes and the APU still shut down with no cooling period. A white stripe displays on the switch

24
Q

Selecting the APU control MASTER selector knob from On to OFF initiates a normal APU shutdown, monitored and controlled by?

A

FADEC

25
Q

How is the APU monitored and controlled?

A

FADEC

26
Q

What will happen if batteries are turned OFF during the 1-minute cool down period?

A

APU will shut down immediately

27
Q

When will automatic shutdown of the APU occur?

A
  • Ground: overspeed, underspeed, FADEC critical fault, fire, EGT overtime, sensor failure, high oil temp, low oil pressure
  • Flight: Overspeed, underspeed, FADEC critical fault
28
Q

The APU can be used for pneumatics to a max of what altitude?

A

15,000 feet

29
Q

What is the max altitude for operation of the APU electrical?

A

33,000 feet

30
Q

What is the max altitude for APU start?

A

30,000 feet

31
Q

Up to what altitude may the APU assist in engine start?

A

21,000 feet

32
Q

On which display would the crew find info regarding the operational status of the APU?

A

EICAS

33
Q

Where would you find the APU RPM and EGT indications?

A

On EICAS

34
Q

If both engine bleed and APU bleed is available which one has priority?

A

Engine bleed

35
Q

During APU start where does the fuel come from and what pump does it use when only DC power is available?

A

Right fuel pump and DC pump until AC power is available, then AC pump takes over

36
Q

With the right engine running and the APU running where does the fuel come from?

A

Engine ejector pump?

37
Q

The AMS controls the APU and engine bleeds. During an engine start what happens to the bleed valves?

A

The APU bleed valve opens which supplies the bleed air for the start. After the start the engine bleed valve opens and the APU bleed valve closes

38
Q

Do you get the APU cool down period when you press the APU emergency stop button?

A

No

39
Q

If you need the APU 50 secs into shutdown is there a way to get it back?

A

Yes, turn the APU master switch back to ON

40
Q

How would you operate the APU while using from from Tank 1?

A

Select XFEED selector to LOW 2

41
Q

In normal operations on the ground with APU running it would be normal to see the fuel imbalanced with less fuel in which tank?

A

Right tank

42
Q

Can the APU be started after a critical fault?

A

No

43
Q

Will the APU auto-shutdown inflight for an APU fire?

A

No

44
Q

What is the APU starter duty cycle?

A
  • 1st and 2nd attempt: 60 secs on/60 seconds off

3rd: 60 secs ON/5 mins off

RJET E170 Study Guide 12B (16 decks)

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