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ATR > Engine - Propeller Control > Flashcards

Engine - Propeller Control Flashcards

1
Q

What is the normal take off power rating?

A

2475 SHP

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2
Q

What is the SHP in case of an engine failure during take off?

A

2750 SHP

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3
Q

Why is the duct S-shaped?

A
  • To remove FOD that may have been ingested by inertia
  • To divide the airflow into a primary flow for the engine and a secondary flow for the oil cooler
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4
Q

What is the accessory gearbox used for?

A
  • driven by the high pressure compressor shaft
  • operates the engine driven fuel pump, an oil pump and the DC starter/generator
  • mounted at the top of the engine
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5
Q

Why is the high pressure spool used for engine starting?

A

It is smaller and lighter weight so easier to spin up

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6
Q

What does the propeller reduction gearbox drive?

A
  • propeller over speed governor (POG)
  • 115 V ACW generator
  • propeller valve module (PVM)
  • high pressure pump
  • fuel cooled oil cooler (FCOC)
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7
Q

How is the propeller driven?

A

Driven by the free power turbine through a reduction gearbox

Spin by exhaust gases

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8
Q

How is propeller pitch controlled?

A

Hydro mechanically controlled by a Propeller Valve Module (PVM) installed on the reduction gearbox

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9
Q

How is propeller pitch changed?

A

Oil pressure supplied by a feathering pump which is supplied by the engines lubricating system

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10
Q

What does the Propeller Electronic Control (PEC) unit do?

A
  • Control their associated PVM as well as the synchronisation of the phases of the propellers
  • Controls the Pitch Change Mechanism through two channels (if one channel fails back up will take over
  • Calculates correct prop speed using altitude and airspeed data and info from the Np sensors
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11
Q

What is the Propeller Interface Unit (PIU)?

A

Provides an interface between the engine controls in the flight deck and the PEC

Two PIUs installed in the electronic rack

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12
Q

What does the Propeller Valve Module (PVM) do?

A
  • provides for governed constant speed operation
  • power lever controlled beta range from idle to full reverse
  • propeller feathering
  • synchrophasing
  • low prop pitch angle protection
  • prop overspend protection
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13
Q

What are the components of the PVM?

A
  • electro hydraulic valve
  • protection valve
  • feather solenoid
  • rotary variable differential transducer
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14
Q

What does the electro hydraulic valve (EHV) do?

A

Meters oil to the pitch change actuator and allows a normal feathering of the prop

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15
Q

What does the feather solenoid do?

A

Acts as a back up to the electro-hydraulic valve

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16
Q

What does the Rotary Variable Differential Transducer do?

A

Adjusts and confirms the power lever angle

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17
Q

Where is the prop brake installed?

A

On a counter shaft of the right engine gearbox

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18
Q

When can the prop brake be engaged?

A
  • aircraft is on the ground
  • prop brake switch in the ON position
  • gust lock must be engaged
  • right CL must be in feather or fuel shut off position
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19
Q

What does the EEC do?

A

Controls the flow of fuel through the HMU (hydro-mechanical Unit) by means of a stepper motor

20
Q

What are the EEC information inputs?

A
  • power lever angle information
  • mode selected on pwr mgt panel
  • position status of the bleed air valves
  • engine parameters
  • air data information
21
Q

What does the EEC fault light mean?

A

Fuel control is ON and there is an EEC failure

Fuel scheduling is fixed at the point at which the failure occurred

If fault occurred with the power lever above 52 degrees, EEC fault light will flash and movement of the affected power lever will not result in a change of power

Deselection of the affected EEC is prohibited while the FAULT light is flashing

22
Q

How can you turn off a fault EEC?

A

Power lever should be moved below 52 degrees and the EEC light will illuminate steady

Once below 52 degrees the power lever is able to control the engine and affected EEC can be selected OFF

What FAULT light illuminates, the ENG light illuminates, master caution and a single chime

23
Q

What happens to the HMU if EEC is selected OFF?

A

The HMU will control the fuel flow and control of the Nh will be based on the associated power lever angle

24
Q

What happens to under speed control when the EEC is selected OFF?

A

It is lost at low power

25
Q

How is manual fuel scheduling controlled?

A

By power lever angle setting

Settings provide fuel demands and control the prop blade angle in the beta range (below 62 degrees)

26
Q

What is Base Law?

A

Used when the associated EEC is inoperative

Fuel control is relative to power lever angle

Changes in ambient conditions will result in changes of Nh so need to adjust the power lever angle in order to maintain the max engine torque

Loss of prop under speed control at low power

27
Q

What is Top Law?

A

Operates when the EEC is on

Will provide Nh over speed protection

Will command a specific engine power based on the rating selected on the pwr mgt panel, the power lever angle, flight conditions and the position of the bleed air valves

28
Q

When is Nh back up law activated?

A

Low power settings, engine torque control failure or in hotel mode

29
Q

What does top law provide?

A
  • minimum prop speed control on the ground and at low power settings
  • automatic uptrimmed take off power in the event of an engine failure on take off
  • controls the modulation of the Handling Bleed valve to optimise low pressure compressor operation
30
Q

What are the modes of propeller speed governing?

A
  • blade angle governing
  • fuel governing
  • the transition mode
31
Q

What is blade angle governing?

A

The normal mode of governing in flight

The PVM adjusts prop pitch to maintain a constant prop speed

Available regardless of EEC status

32
Q

What is blade governing mode?

A

The pwr mgt selector commands the prop speed through the PEC and the power levers command power

33
Q

What is fuel governing mode?

A

Used at low speed and low power

EEC automatically increases fuel flow to maintain a minimum prop speed

Available when the associated condition lever is in the AUTO

Not available when associated EEC is OFF or prop is feathered

34
Q

What is transition mode?

A

Active when aircraft is on the ground or in flight at low power settings and low speed

Prop speed will be between 70.8% and 100%

35
Q

What is the flight beta range?

A

Power lever movement above FLT IDLE

36
Q

What is ground beta?

A

Range between FLT IDLE and MAX REV

37
Q

When is the FLT IDLE gate unlocked?

A

As soon as one landing gear shock absorber is compressed

38
Q

What do the condition levers provide input to?

A

The PVM and the HMU of the associated engine

39
Q

What sets propeller RPM in the forward thrust constant speed range?

A

The condition levers through input to the governor in the PVM

40
Q

What is prop RPM at 100% override?

A

1200 RPM

41
Q

Where are the lift gates on the condition levers?

A

AUTO to prevent movement from auto to feather

FEATHER to prevent movement from feather to fuel shut off

42
Q

What does the Automatic Takeoff Power Control System (ATPCS) provide?

A

Auto prop feathering on the failed engine and power uptrim on the non affected engine

43
Q

When is the ATPCS system armed?

A
  • pwr mgt set to take off
  • ATPCS pb pushed in
  • both power levers above 49 degrees
  • both torques above 46 degrees
  • aircraft on the ground

Also armed in flight given the conditions but no uptrim logic once pwr mgt selector out of take off position

44
Q

When does power uptrim occur?

A

2.15 secs prior to prop auto feather

45
Q

What does the fuel governing cancel signal do?

A

Permits the feathering prop to decrease RPM through an underspeed condition

46
Q

How is the ATPCS disabled in flight following an engine failure?

A
  • selecting any position other than TO on pwr mgt
  • selecting ATPCS pb to OFF
  • retarding both power levers

UPTRIM light extinguishes

47
Q

How can the prop be unfeathered after a restart?

A

Only by selecting MCT position on the pwr mgt panel after engine has been started

ATR (25 decks)

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