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Dash 8 > Powerplant > Flashcards

Powerplant Flashcards

1
Q

How much SHP for Q200 (including up trim)

A

1950SHP uptrim to 2150SHP

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2
Q

How much SHP for Q300 (including up trim)

A

2140SHP uptrim to 2380SHP

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3
Q

How many sections to PW123D engine

A

3 sections (3 shafts)

Low Px Compressor (NL)
High Px Compressor (NH)

High Px Turbine
Low Px Turbine

2 stage Power Turbine

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4
Q

How is pressurised oil supplied to engine

A

Gear driven Oil Pump from Accessory Gearbox

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5
Q

How is heated Oil cooled

A

Oil is cooled by air in the engine intake duct
&
Cooled by a Fuel/Oil heat exchanger
(cold fuel will cool the oil)

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6
Q

If there is a catastrophic loss of engine oil can the prop still be feathered

A

Yes.

An independent reservoir of engine oil in the reduction gearbox is available to be used by the Auxiliary Feathering Pump

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7
Q

How is the Accessory gearbox driven

A

By a shaft connecting it to the Nh Compressor rotor

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8
Q

What does the Accessory Gearbox drive

A

FOD
Fuel Pump
Oil Pump
DC Starter/Generator

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9
Q

How is the DC Generator cooled

A

The DC Gen is air cooled

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10
Q

What is the Start process

A
  1. Starter cranks Nh rotor through 10-19%
  2. CL moved to START FEATHER to introduce fuel
  3. 25% Nh ECU takes control of fuel schedule (ground idle)
  4. ECU accelerates Nh to 76%
  5. Start sequence terminates at 63% Nh
  6. DC Starter/Generator changes to Generator mode
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11
Q

What does the Prop Reduction Gearbox drive

A

OPRAH minus the R

Hydraulic Pump
PCU
Overspeed Governor
AC Generator

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12
Q

In Beta mode what do the Power Levers control

A 
Engine Speed &
Blade Angle (direct input to PCU)
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13
Q

What are the 3 functions of the Condition Lever

A
  1. Introduce/Terminate fuel to the engine via shutoff
  2. Feathering of the propeller
  3. Constant speed governing of propeller via blade angle in forward thrust range (900-1200RPM)
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14
Q

What are the functions of the ECU

A
  1. Propeller Underspeed governing
  2. Propeller governing in reverse
  3. Fuel scheduling for ground idle
  4. Fuel scheduling in forward power range
  5. HBOV operation
  6. Quiet taxi mode
  7. Power up trim
  8. Tq signal to Tq indicators
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15
Q

How is fuel scheduling conducted in ECU MANUAL mode

A

Fuel scheduling will be fixed at point of failure

Fuel schedule then selected by Power Lever movement and Condition Lever movement

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16
Q

What happens to the Engine Tq when the ECU fails

A

Either no change or Tq will increase by 8-10%

There may be a split in PL to achieve symmetrical Tq

NOTE: No change before Climb Power set

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17
Q

What are the 2 indications that an ECU has failed or gone into MANUAL reversion

A

Caution lights #1 ENG MANUAL
AND
“MANUAL” in amber on ECU MODE control panel

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18
Q

What automatic functions are lost with an inoperative ECU

A

Np under speed protection

Uptrim

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19
Q

How does the ECU protect against Np under speed

A

The ECU keeps Np out of the restricted range (500-780RPM) by adding fuel to increase Nh, thus speeding up the prop

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20
Q

Where is the HBOV situated

A

Inline with the Low Px Compressor (p2.5)

21
Q

What is the role of the HBOV

A

It bleeds LP Compressor air to prevent Compressor stall and surge at low power settings
It also aids in reducing engine noise

22
Q

How does the Uptrim system work

A
  1. Autofeather system is armed (Tq above 38% on both engines and PLA/OAT requirements satisfied
  2. Engine fails and Tq reduces to 28%
  3. Armed SCU detects 28% on inoperative engine and 38% on operative engine
  4. Triggered SCU sends power up trim signal to ECU on operative engine

3 second delay

  1. SCU of affected engine initiates AutoFx
  2. ‘Np under speed fuel governing cancel’ signal sent to inoperative engine ECU
  3. Auxiliary pump energised for 18 secs to allow feathering
  4. Interlock engages to prevent AutoFx of second propeller
23
Q

How much is power increased during up trim

A

10%

24
Q

What are the 5 main components of the Propeller System

A
  1. PCU
  2. Prop Overspeed Governor
  3. AutoFx system
  4. Alternate Fx system
  5. Synchrophase system
25
Q

What are the 3 ways to feather the propeller

A
  1. Automatic mode during AutoFx sequence
  2. Manually moving CL to START & FEATHER
  3. Using the Alternate Fx system
26
Q

How does the PCU work

A

The PCU regulates oil px to a double acting pitch change mechanism inside the hub.

Constant and Metered Oil px

27
Q

What is metered oil referred as and what meters it

A

Fine Pitch Oil and is metered by the PCU

28
Q

What is unmetered oil referred as

A

Constant Pitch oil (coarse)

29
Q

Fine pitch oil drives the propeller…

A

To a lower pitch, reducing blade angle and increasing speed

30
Q

Constant oil drives the propeller….

A

To a high pitch, increasing blade angle and decreasing speed ultimately to Fx

31
Q

How is feathering accomplished

A

By dumping metered oil (fine pitch oil) allowing constant oil to drive the blade to Fx

32
Q

Where is the Synchrophase system located

A

On the #2 PCU

33
Q

How is a feathering prop indicated

A

Np reduces through the 12 o’clock position moving towards 0

34
Q

How is a propeller feathered manually

A
  1. Moving the CL to START & FEATHER
  2. Manual feathering valve in PCU is opened
  3. Metered oil is dumped
35
Q

How does the Prop Overspeed Governor work

A

Hydraulically controlled in constant speed and flight beta at 1250RPM

  1. Np exceeds certain value
  2. Flyweight governor detects overspeed condition
  3. POG dumps metered oil
  4. Constant oil coarsens the blade towards feather
  5. Prop is slowed aerodynamically
36
Q

How does the Prop Overspeed Governor work on the ground

A

Pneumatically controlled in ground beta at 1308RPM

  1. POG has pneumatic section for P3 air
  2. P3 air is bled off
  3. As MFC uses P3 air for fuel scheduling, fuel will be reduced
  4. Prop is slowed down as engine slows down
37
Q

How does the Beta Backup system work

A
  1. A PCU malfunction causes the prop to enter beta ground range in flight
  2. Beta Backup system will open Feather Solenoid valve
  3. Metered oil (fine pitch) will be dumped
  4. Propeller blade angle will begin to feather and increase out of ground range.
  5. Once past the ground range point, the low blade angle switch closes the feather solenoid valve and the cycle continues.
38
Q

If a loss of oil px were to cause the blade angle to begin to change angle by itself what will happen

A

The pitch lock will activate in the pitch change mechanism

This will prevent aerodynamic loads from changing the prop more than 1 degree or by 2% in speed

This can be overridden by using the Alternate Fx system

39
Q

What will happen with an ECU in MANUAL mode on landing

A

As the PL are moved to flight idle the prop rpm will decrease into the restricted range. Normally the ECU would prevent this. High Tq will be required to keep the prop out of the restricted range, the prop should therefore be feathered during taxi.

40
Q

Aerodynamic loads drive blade angle to…

A

Fine or low blade angles

41
Q

When will the propeller ground range lights illuminate

A

When the low blade angle switch is activated by blade angle passing 16 degrees

42
Q

When do the ENGINE INTAKE HEATERS come on

A

When the Bypass doors are open and the temp is below 15 degrees

43
Q

How is heater operation prevented with the engine shut down

A

An oil px switch

44
Q

What is the capacity of the Engine Oil system

A

6 USG

45
Q

What is the capacity of the independent oil reservoir for Alternate Fx

A

1.7 US Quarts

46
Q

When will the #1 ENG OIL PRESS warning light illuminate

A

42 +/- 2PSI

47
Q

What path does the oil take throughout the engine

A
  1. Sump
  2. Oil pump
  3. Oil cooler
  4. Filter
  5. PRV
  6. Fuel Heater
  7. Oil network
  8. Reduction gearbox
  9. PCU pump
  10. Aux fx pump
48
Q

What component of anti ice uses engine oil

A

The engine inlet splitter uses hot engine oil

49
Q

How is oil returned to the sump

A

3 gear type scavenge pumps.

Dash 8 (7 decks)

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