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PEGS Homework > Powerplant > Flashcards

Powerplant Flashcards

1
Q

Under what circumstances does an automatic up trim occur? What percentage increase of set power does automatic up trim provide.

A

Automatic up trim occurs when one engine drops to below 28% torque and the other remains at >38%, it increases by 10% set power. Arming occurs at 38% and power lever angle.

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2
Q

How many spools are there in the gas generator?

A

2 spool, LP and HP

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3
Q

The engine can remain running with oil pressure between 40 and 55 psi with a maximum Nh of?

A

<75%, this means the engine will need to be feathered.

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4
Q

What is the function of the accessory gearbox?

A

It drives the fuel pump, oil pump, DC generator/starter motor

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5
Q

What other gearbox driven accessories are there and where is the gearbox?

A

The propeller gearbox is the other gearbox on the aircraft and drives the AC generators, overspeed governor, PCU pump and hydraulic pump.

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6
Q

What oil is used to control prop blade pitch?

A

Engine oil

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7
Q

Describe the “BETA” range?

A

In BETA range the power lever controls blade pitch by bleeding more or less oil to the sump. The ECU maintains propeller RPM through varying fuel flow.

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8
Q

Is it possible for a power lever to be moved below FLT IDLE during flight?

A

Yes however it is prohibited and the beta lockout system would be activated.

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9
Q

What is the recommended Nh range before selecting fuel on? What is the maximum permissible ITT during an engine start?

A

10-20% Nh for fuel introduction. Max start temp is 950deg C.

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10
Q

If an engine fails to light-off within ten seconds of initiating fuel flow what should your actions be?

A

Condition lever fuel off, ignition off, motor for 15 seconds, start select off.

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11
Q

When is the engine ECU rating selector selected to the TOP position?

A

For the 300 series in all operations. For the 200 series during take-off and on descent inbound.

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12
Q

If an engine ECU / EEC goes into reversion, what happens to engine power?

A

The engine power remains at the set position and the power lever directly controls fuel flow.

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13
Q

Where must the CONDITION LEVER be positioned before selecting the alternate feather switch to the alternate feather position if required to feather the propeller?

A

The condition lever must be below min.

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14
Q

What causes a power uptrim? How do you know it has occurred?

A

If during takeoff with autofeather armed an engine fails, the remaining engine will uptrim and the uptrim light will illuminate.

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15
Q

Failure of the No.1 ECU on take-off prior to setting climb power will be indicated by?

A

1 ENG manual caution light

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16
Q

What is normal engine oil pressure? The engine must be shut down if the oil pressure drops below? When must oil QTY be checked?

A

55-65PSI is normal,
engine must be shutdown below 40PSI
Oil QTY should be checked ideally 15minutes after shutdown, not more than 30.

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17
Q

What is the prop restricted range? Which engine component is responsible for preventing Np under-speed? What is the maximum rpm when at MAX?

A

500-780 RPM which is a resonant range, the ECU provides underspeed governing usually at 785RPM, 1212RPM is maximum, higher than this is an overspeed.

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18
Q

Can a prop ever enter the prop restricted range?

A

Yes it can, it will during start and shutdown and can if the ECU fails. If in an abnormal this is acceptable.

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19
Q

What happens if NH overspeeds?

A

ECU reduces fuel flow to the engine.

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20
Q

How is autofeather armed?

A

if the autofather is selected it will arm when torque is increased above 38%

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21
Q

When does autofeather occur?

A

When autofeather is armed and one engine torque drops to below 28% with the other remaining at >38%

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22
Q

How is propeller over-speed protection provided?

A

At 1250RPM the feathering solenoid will dump metered oil pressure to the sump (hydraulic). At 1308RPM the overspeed governor will signal the MFC to limit fuel flow (pneumatically)

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23
Q

What happens if total oil pressure to the PCU is lost?

A

The pitch lock will engage and stop the propeller from moving more than 1deg or 2%RPM

24
Q

How does the synchrophase system work?

A

The RPM of both propellers must be within 20RPM of each other, the synchrophase will slave the No.2 to the No.1 in both phase and RPM.

25
Q

How is ignition activated? What are the starter engagement limits?

A

The start select switch is selected to 1 or 2, this arms the start circuits. pressing the start light begins the sequence. the limits are 1 min on 2 mins off twice then 30 mins rest.

26
Q

What is the purpose of the intake bypass doors? What conditions must met before the intake heaters operate?

A

The bypass doors enable foreign objects to pass through the nacelle without entering the engine. The heaters operate below 10deg, mod 8/0928 15deg.

27
Q

Where can you read shaft horsepower?

A

Torque gauges give percentage shaft horsepower

28
Q

Normal take-off RPM?

A

1200

29
Q

What is the restricted RPM range?

A

500-780

30
Q

Name all rotating parts of the engine

A

LP and HP centrifugal compressor, LP and HP turbine and the free power turbine

31
Q

What is the accessory gearbox?

A

provide a source of power to drive accessory functions required for engine operation

32
Q

What is the MAX torque allowed on the PW123D?

A

114.2% @ 900RPM

33
Q

What is the MAX ITT allowed on the PW123D?

A

800 deg C

34
Q

IF the torque momentarily increased above the maximum would the aircraft be grounded?

A

Not necessarily there are transient limits.

35
Q

How many blades are there on the propeller?

A

4

36
Q

Where can you read propeller blade angle?

A

You can’t.

37
Q

What RPM is the propeller governed to at MAX?

A

1200

38
Q

What RPM is the propeller governed to at MIN?

A

900

39
Q

What prevents inadvertent movement of the condition levers?

A

Detents known as gates, the condition levers must be lifted to move back past them.

40
Q

What are the main functions of the ECU?

A 
Ground idle fuel scheduling
Prop underspeed governing
Prop governing in reverse
Quiet taxi mode
Fuel scheduling in the forward power range
Power up trim
HBOV operation
41
Q

What is the MCR bug for?

A

Suggested maximum cruise power

42
Q

What is the MCL bug for?

A

Suggested maximum climb power

43
Q

What unit is responsible for initiating auto Fx

A

Signal Condition Unit (SCU) which monitors torque on both engines

44
Q

What is the TOP setting for?

A

it de-energises the torque bugs and relates to take-off power and allows power up trim to occur automatically

45
Q

What happens if the ECU selector is not in TOP for take-off?

A

Fuel may not be scheduled appropriately, config warning horn and power up-trim won’t be available.

46
Q

What provide Nh overspeed protection?

A

at 105.8% Nh, P3 air is dumped reducing airflow through the high speed compressor and therefore into the combustion chamber the ECU will sense this and reduce fuel flow.

47
Q

How is oil temperature controlled?

A

via and oil cooler at the rear of the intake duct that automatically opens and closes a door based on sensed oil temp.

48
Q

What gauges monitor engine operation?

A 
TQ
Np
ITT
Fuel Flow
Nh
Nl
Oil temp
Oil pressure
49
Q

How many fuel nozzles are there? Igniters?

A

14, 2

50
Q

How many power turbines are there? compressor?

A

2 power, one each per compressor

51
Q

What is the maximum normal ITT? and uptrim?

A

765 deg C, Uptrim 800deg C

52
Q

What is the ECU and what information is fed into it?

A

Electronic Control Unit, Engine/propeller speeds, torque and ambient conditions
It responds from inputs from the power and condition levers.

53
Q

What indication does one get if a malfunction occurs in the ECU?

A

1/2 ENG MANUAL caution light, the ECU pushlight does not illuminate

54
Q

What is the difference between auto and norm ignition systems?

A

Auto comes on automatically below 60% Nh, norm doesn’t.

55
Q

Why do we keep the condition levers in start Fx for 30sec?

A

So that oil from the PCU can return to the sump

PEGS Homework (18 decks)

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