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Mesa E-175 Oral Prep 2022 (just updated) > APU > Flashcards

APU Flashcards

1
Q

What kind of APU do we have and describe it?

A

Sundstrand 2300, single-stage impeller with 2 stage axial-flow turbines

  1. Independent oil system
  2. Independent AC Generator
  3. APU bleeds can run AirCon, Water pressurization, cabin pressurization (primarily on ground)
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2
Q

When does the APU auto shutdown in flight?

A
  1. Overspeed
  2. Underspeed
  3. Critical Fault
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3
Q

When does the APU auto shutdown on the ground?

A
  1. Overspeed
  2. Underspeed
  3. Critical fault
  4. High oil temp
  5. Low oil pressure
  6. Fire
  7. Overheat
  8. Sensor Failure
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4
Q

What does selecting the OFF position on the APU selector do?

A
  1. removes pneumatics only (only electrics for 1 min)

2. Starts 1 min cooldown period

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5
Q

When is electrical and pneumatics available from the APU after APU start?

A

95% plus 3 seconds

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6
Q

What controls the APU?

A

Its dedicated dual channel FADEC

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7
Q

What battery is used for APU Start?

A

BATTs 1 (FADEC & EICAS) and 2 (APU Start Bus)
or
BATTs 1 and DC GPU

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8
Q

What is the fuel source for the APU?

A
  1. Right fuel tank

2. X-feed (Low 2)

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9
Q

What fuel pump is used to start the APU?

A
  1. If no engines on and AC power is avail then ACMP2
  2. No AC power then DCMP
  3. Right Eng ON then right Eng 2 primary ejector pump
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10
Q

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

A

Yes

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11
Q

Can APU shutdown be cancelled?

A

Yes, moving the APU start switch back to ON before 1 min cooldown period is over

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12
Q

How can the APU be shutdown immediately?

A
  1. APU EMER STOP is pressed

2. BATTs are turned OFF during 1 min cooldown

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13
Q

Can the APU be started after a critical fault?

A

No

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14
Q

Max start EGT for APU Start?

A

1032˚ C

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15
Q

Max EGT for continuous operation?

A

717˚ C is start of the Red; amber is permitted 662˚ - 717˚

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16
Q

Max Rotor Speed of the APU?

A

108%

17
Q

Max continuous and transient oil temps for the APU?

A

155˚ C and 163˚ C (up to 15 mins)

18
Q

What are the electrical numbers associated with the APU AC Generator?

A

115 VAC, 400 Hz, 3-Phase, 40 KVA

19
Q

Which fuel pump provides fuel supply to APU during engine start with AC GPU avail, unavail, and after engine start?

A

AC Avail for start = ACMP2
AC Unavail = DCMP
After Engine #2 Start = primary ejector in right integral tank

20
Q

Can you restart the APU after receiving a APU Fail EICAS Message?

A

No; automatic shutdown has occurred;

21
Q

APU Bleed Priority

A
  1. A/C on Ground
  2. GS below 50 kts for more than 30 secs after touchdown
  3. Packs off AND A/I not ALL or Single-Engine Taxi
  4. APU normal, APU bleed & x-bleed buttons pushed in (auto)
22
Q

What 3 things open or are energized when you move APU Start Knob to ON?

A
  1. APU FADEC is energized
  2. APU EICAS messages are displayed
  3. APU Fuel SOV opens
23
Q

What is closed when the APU Emer. Stop Button is pressed?

A
  1. Denergizes APU FADEC
  2. Closed APU Fuel SOV
  3. Overrides APU Master Switch
24
Q

How many duplex and simplex fuel injectors are used in the APU Fuel Distribution?

A

6 Simplex (APU Run) from secondary fuel manifold; 6 Duplex (APU Run and Start) from primary and secondary fue manifolds

25
Q

How many igniters and exciters for the APU?

A

1 exciter, 2 gap-type igniter plugs

26
Q

What powers APU Start Sequence?

A

Batt 1 FADEC, Batt 2 APU Start Bus which powers Electronic Starter Controller –> Brushless Starter Generator (attached to rotor shaft for APU Start, basically electronic version of Air Turbine Starter)

27
Q

What provides the EICAS with APU temp information?

A

2 thermocouples located in the exhaust section of the APU that are dangling in front of outgoing exhaust air

Mesa E-175 Oral Prep 2022 (just updated) (20 decks)

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