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Dash 8 Q400 1 > Powerplant > Flashcards

Powerplant Flashcards

1
Q

How many stages in the LP and HP compressors?

A

LP: 3 axial

HP: 1 centrifugal

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2
Q

What does the reduction gearbox drive?

A

Prop
AC generator
Hydraulic pump
Overspeed governor and pump

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3
Q

What is on the accessory gearbox?

A

Accessory

EDP                                
Oil pump                         
Starter Gen                     
Regenerative fuel pump 
Perm magnet alternator
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4
Q

What is on the prop reduction gearbox?

A

Prop govenor
PCU oil pump and prop overspeed governor
AC Gens
Eng driven hydraulic pump

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5
Q

What is the start sequence?

A
  • @ 8% rpm ignition and fuel flow
  • 2nd igniter on if no ignition in 8 sec
  • @ 50% rpm, starter cutout, ignition off, engine accelerates to 64.2% and starter becomes a generator.
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6
Q

What is start protection?

A

FADEC cuts fuel if:

  • no light in 16 seconds
  • ITT > 920°C
  • NH doesn’t get to 50% in 70 seconds
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7
Q

When does all oil bypass the cooler?

When does all oil go through the cooler?

At what psi does the oil bypass?

A

77°C

85°C

23 psi

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8
Q

How are engine speeds monitored?

A

Magnetic pulse pickup probes

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9
Q

BETA is inhibited unless…

A

RA

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10
Q

Describe function of RDC NP button on engine control panel

A

Keeps prop at 850 RPM for landing in order to reduce noise. When condition leavers are advanced to 1020 RPM, unless PLA is advanced beyond 60° then RPM increases to 1020 RPM.

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11
Q

What does the event button do?

A

Live snap shot of 79 engine parameters for previous 2 minutes and 1 minute after.

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12
Q

When does the FADEC activate?

What is the purpose of the FADEC?

When will the FADEC command both igniters to operate?

A

When you push the start button.

To control all engine fuel demands.

  • No ignition after 8 seconds of fuel selected on.
  • Flame out
  • Surge or compressor stall
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13
Q

How many igniters are used in a start and when does it get excited?

When does it go off?

What controls ignition during start?

Where are the igniters located?

A

2 but 1 used during start and the other used for next start.

On @ 8% then off at 50%

FADEC

4 & 7 O’clock

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14
Q

How many fuel nozzeles?

A

12

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15
Q

What are permanent magnet alternators for?

What happens if the PMA fails?

A

FADEC and PEC when NH > 20%

Essential busses power the FADEC.

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16
Q

What is the MTOP limit?

A

10 minutes

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17
Q

What is uptrim and how is it commanded?

What are the indications of uptrim?

A

Increase of 10% torque unless already at MTOP. The failed engine PEC sends a message to the other engine FADEC to uptrim when there is a torque loss of 25% or Np decreases to less than 816 rpm and the power leavers are in detent.

Reverse video “UPTRIM” on ED. Increase of 10 in torque. If at NTOP then power increase to MTOP.

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18
Q

How do you set MCP when doing an MTOP takeoff?

A

Set bleeds to norm or max

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19
Q

What is the gearbox reduction ratio and how many stages of reduction are there?

A

17:1 to 1

2 stages

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20
Q

What would engine indications normally be at reverse?

A

950 RPM

35% torque

1500 HP

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21
Q

When does the OSG kick in and how does it work?

A

It kicks in at 1060 RPM. It is driven by the reduction gearbox. FlyWeights block servo valve controlling oil pressure. Blades will coarsen.

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22
Q

What is the minimum prop blade angle in flight or when power leavers above FI?

What is this known as?

A

16.5°

Soft stop. To comply with BETA lockout control

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23
Q

What happens if blade angle decreases to 16°?

A

Prop ground range lighting come on

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24
Q

What is auto underspeed protection?

When does it arm?

When is it active?

A

PECU software failure so prop doesn’t feather uncommanded and FADEC doesn’t schedule more fuel.

Armed: 
PLA above flight idle
CLA above feather
Torque >50%
NP above 816 rpm
Auto-feather and alternate feather inactive

Active:
Torque >50% and NP below 816 rpm

25
Q

How is NP measured?

A

Magnetic pickups monitoring target screws on slip rings.

26
Q

When is autofeather armed?

When is it active?

A

Armed:

Both PLA > 60°
Both torques >50%
and AF select switch depressed

Active:

  • Torque drops 25% or more for 3 seconds.
  • PECU outputs a servo valve signal
27
Q

What is the autofeather delay?

A

3 seconds. This is for pilot decision for RTO.

28
Q

What is the first level of overspeed protection?

2nd level?

A

1060RPM. Hydraulic. OSG rellieves oil pressure.

FADEC reduces fuel at 1120RPM

29
Q

What is safe course pitch?

A

60° If engine loses all oil, prop moves to safe coarse pitch?

30
Q

What is the min voltage to start engines?

A

27v

31
Q

What is the HP at MTOP?

NTOP?

A

5071 HP

4580HP

32
Q

What is the NP on the ground when power leavers are between disc and FI?

A

660 RPM

33
Q

What are the RPM indications of a feathered propeller when the engine is dead, and live?

If unsure if the prop is feathered or not, what other indications can verify a feathered propeller?

A

Dead: 0-100RPM
Live: 200-500RPM

-Decreasing EGT and NH 40% stable or falling.

34
Q

How is the FADEC powered?

A

Left Ess Bus till 20% NH then Permanent Magnet Alternator.

35
Q

What is AUPC?

When is it armed?

When is it triggered?

Which caution light gets triggered?

A

Automatic Underspeed Protection Circuit protects against failures that drive the propellers to coarse pitch.

PLA at or above FI.
Torque above 50%.
Autofeather and alternate feather not active.
Condition leaver above start and feather.

Triggers when No drops below 816 RPM and torque remains above 50%.

PEC caution light gets triggered.

36
Q

After setting the condition leavers to start and feather, why do we have to wait 30 seconds?

A

Because engine oil could be trapped in the reduction gear box.

37
Q

What is the purpose of the FADEC?

What are the inputs to the FADEC?

When does FADEC activate?

A

It controls all engine fuel demands.

Torque, Np, Nl, Nh, ambient conditions.

When you push the start button. It controls ignition and start sequence.

38
Q

What is the difference between an engine start in the air as opposed to the ground?

A

Auto abort circuitry and ITT over temp protection is disabled. Both igniters are also used in an air start.

39
Q

What power level, does pushing past the detent give you?

A

125% torque

40
Q

How many Handling Bleed Off Valves (HBOVs) and what is the location and purpose of each?

A

2 HBOVs to provide surge protection.

At 2.2 LP compressor provides steady state surge protection.

At 2.7 HP compressor provides transient and start protection.

41
Q

What is the purpose of the torque limiting feature? What are the ranges?

A

Reduces Nh to prevent torque excedence of 135%.

Forward range 106%

Over travel 125%

Reverse 35%

42
Q

How can you cancel MTOP?

A

Push the MTOP button.

Move the power levers out of detent.

Move condition leavers out of 1020 RPM.

43
Q

What is the purpose of the counterweights in the propeller in normal operation and in reverse?

What happens if a hydraulic failure occurs during reverse?

A

Twists to safe course pitch.

In reverse it twists towards maximum reverse angle.

In a hydraulic failure during reverse, the counterweights will twist the props to the maximum reverse angle.

44
Q

What powers the propellers to fine pitch?

A

Oil pressure

45
Q

What controls blade angle in the flight beta range?

A

Power levers

46
Q

Describe the alternate feather system.

What condition is required for it to work?

A

28 VDC pump activates for 30 seconds.

Condition lever must be aft of start and feather gate. This is good so we can’t accidentally activate it.

47
Q

What is required for an auto feather test?

A

Power levers must be in disc and condition levers in start and feather or fuel off.

48
Q

What is the accessory gearbox driven by?

A

Gear driven by the NH shaft.

49
Q

What is driven by the accessory gearbox? (5)

A 
High pressure and oil scavenge pumps.
High pressure fuel pumps.
Permanent magnet alternator.
DC starter generator.
Regenerative fuel pump.
50
Q

When should the bypass doors be opened?

5

A 
Icing conditions.
Heavy precipitation.
Bird activity.
Gravel runway operations.
Contaminated runways.
51
Q

When will the FADEC turn on both igniters during start?

A

If an ITT increase of 20C is not recorded after 8 seconds of fuel flow being selected on.

52
Q

How does FADEC recognize a ground / air start?

A

75 Kts CAS if airspeed is valid otherwise WOW.

53
Q

What is idle Np on the ground with the condition levers at min or greater?

What is this known as?

What is the Np with condition levers at start and feather.

A

660 rpm

Prop underspeed governing.

220 rpm

54
Q

Where is a FADEC advisory displayed?

A

ED

55
Q

What does the propeller control system consist of?

A 
PEC
PCU 
High pressure PCU oil pump and OS governor
Prop system sensors 
Alternate feathering pump
56
Q

What are the basic functions of PEC?

What are the safety functions of the PEC?

A

RPM and Pitch

AUPC, UPTRIM, and autofeather

57
Q

At what blade angle would the Prop Ground Advisory lights come on?

A

16 degrees

58
Q

What is the purpose of the ground beta lockout system?

A

It prevents blade angles lower than flight fine if the power leavers are inadvertently moved below flight idle.

59
Q

What does over travel on the power leavers produce?

What is this called?

A

1.25 x MTOP and 1020 RPM on Np even if conditions levers are set to a lower setting.

Emergency power.

Dash 8 Q400 1 (21 decks)

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