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MTPC > Power Plant > Flashcards

Power Plant Flashcards

1
Q

The engine is composed of how many and what modules?

A

The engine is comprised of four modules: the accessory section module, cold section module, hot section module, and the power turbine module.

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2
Q

The four modules of the engine can be associated with two sections. What are they and give a description.

A

The four modules of the engine can be associated with two sections: Ng and Np.

The Ng section (Gas Generator) is the part of the engine that makes the power. Ng is comprised of three sections modules: Cold section module, Hot section module, and Accessory section module.

The Np section (Power Turbine Section) is represented by its own module and converts the Ng’s gas pressure into rotational shaft energy that is transferred to the helicopter drivetrain. Cold Section Module: Inlet Section. The inlet section includes the components forward of the compressor.

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3
Q

Green wires

Yellow wires

Blue wires

Black wires

White wires

A

goes to cockpit

engine control/electrical

np overspeed

engine ignition

interface to airframe (cross talk)

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4
Q

DEC Functions

A

Maintin NP at 100%

TGT limiting

Load sharing

Power turbine overspeed protecton (120% plus/minus 1%)

(Hot start prevention)

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5
Q

Hydromechanical Unit (HMU) Functions and Decription

A

1 The HMU schedules fuel for combustion. It contains a high-pressure pump. The HMU has an actuator that positions the inlet guide vanes, stages 1 and 2 compressor variable vanes, and anti-icing bleed and start valve.

2 The HMU responds to engine inlet air temperature (T2), to compressor discharge air pressure (P3), and to a trim signal from the ECU/DEC to set fuel flow and variable vane positioning.

3 The HMU also responds to two separate inputs from the aircraft. The HMU load demand spindle (LDS) is connected to the aircraft collective pitch linkage. The LDS moves when the operator selects a different collective pitch angle.

The HMU power available spindle (PAS) is connected to the ENG POWER lever in the cockpit. It is used to start the engine, to manually set gas generator speed from ground idle to maximum power, and to shut down the engine.

4 A variable electrical trim signal from the ECU/DEC is used in the HMU to vary fuel flow, controlling engine power. Some ECU/DEC failures can be overridden from the cockpit by momentarily moving the ENG POWER CONT lever into LOCKOUT and manually controlling engine power by positioning of the lever.

5 The engine fuel system must be primed after an engine is installed in the aircraft or whenever the fuel system has been opened for maintenance purposes. When the ENG POWER CONT lever is advanced to LOCKOUT, a valve in the HMU will open, allowing fuel flow to purge the system of air. The aircraft fuel pump is used to pump fuel from the aircraft fuel tanks to the HMU. When fuel flows from the overboard drain move the ENG POWER CONT to off.

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6
Q

What does the acronym TGT stand for?

A

Turbine Gas Temperature

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7
Q

What are the four positions of the PCL?

A

OFF, IDLE, FLY, LOCKOUT

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8
Q

What does the acronym HMU stand for?

A

Hydromechanical Unit

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9
Q

Where is the LDS cables connected to for both LDS Spindles to be moved at the same time?

A

MMU

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10
Q

Are the axial stages through the GG rotors part of the Ng Section?

A

Yes

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11
Q

How does the NG section initially begin to rotate?

A

By the PTO

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12
Q

The number three bearing is a ball bearing, which absorbs the ________ and ________ load.

A

The number three bearing is a ball bearing, which absorbs the axial and radial load.

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13
Q

The cast exhaust frame contains the ________ and bolts to the aft flange of the power turbine case.

A

The cast exhaust frame contains the C-sump and bolts to the aft flange of the power turbine case.

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14
Q

There are ________ stages of axial compression in the T701C engine.

A

There are 5 stages of axial compression in the T701C engine.

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15
Q

What section of the engine mechanically drives RPM R?

A

Np section

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16
Q

Is the Ng section mechanically connected to NP?

A

No

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17
Q

What is the connection between Np and RPM R?

A

One-way mechanical connection via the free-wheeling unit

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18
Q

What drives the accessory gear box?

A

Gas Generator (at a variable speed)

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19
Q

How many stages are there in the compressor section (Ng)?

A

There are 6: 5 axial and 1 centrifugal

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20
Q

What are the two operational sections of the engine?

A

Ng and Np

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21
Q

What are the three subassemblies that make up the oil filter?

A

The three subassemblies that make up the oil filter are the filter element, bowl and impending bypass indicator, and the bypass valve and inlet screen.

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22
Q

The scavenge screens collect particles before they enter the ________.

A

The scavenge screens collect particles before they enter the lubrication and scavenge pump.

23
Q

Where does the scavenge oil flow to after it goes through the scroll vanes?

A

The scavenge oil flows to the oil tank after it has been through the scroll vanes.

24
Q

What is the service capacity for the engine oil?

A

7 quarts

25
Q

Where is the oil drawn from for the emergency oil system?

A

Sumps A and B

26
Q

How does engine oil cooling occur?

A

Liquid to liquid cooler, oil flow through the scroll vanes

27
Q

How does the oil system overcome high pressure during cold starts?

A

Oil filter bypass valve, liquid to liquid cooler bypass valve

28
Q

Alternator has 3 windings

A

Ignition power

DEC/ECU power

Ng Signal

29
Q

Is there a DAS plug in a L model EDECU?

What DEC code should appear in a L model?

A

NO, the plug receptacle should have only a dust cover.

DEC codes should read 15

30
Q

EDECU contingency power factors

A

Np below 96%

Greater than 3% droop between reference and Np

Greater than 5%/sec Np droop and Np less than reference

31
Q

DEC Provides what?

A

Signals to the cockpit

Load sharing/Tq stabilization

Engine speed trim to meet demand speed reference

TGT limiting

Hot Start Prevention (DEC Only)

Np Overspeed

32
Q
A
33
Q

Thermocouple Assembly

A

Made of mixed metals to provide voltage when heated

7 probes; average is taken

signal into TGT amplifier on DEC

history counter

HMU

34
Q

Which component provides electrical power to the engine?

A

Engine alternator

35
Q

How does the cockpit receive the Ng signal?

A

From the Ng winding of the alternator

36
Q

What happens If Ng signal is lost?

A

ENG OUT warning light and audio, and 0% Ng

37
Q

The engine mounted electrical alternator supplies AC power to the ignition exciter and the _________.

A

The engine mounted electrical alternator supplies AC power to the ignition exciter and the Digital Electronic Control (DEC).

38
Q

The ignition system is an AC powered capacitor discharge _________ type system.

A

The ignition system is an AC powered capacitor discharge low-voltage type system.

39
Q

What type of special tolerance, oxidation resistant wire, is the thermo elements of the thermocouple harness made of?

A

The thermo elements of the thermocouple harness are made from special tolerance, oxidation resistant chromel-alumel wire.

40
Q

The blue electrical cable carries signals between the torque and overspeed sensor, DEC, and the ________.

A

The blue electrical cable carries signals between the torque and overspeed sensor, DEC, and the ODV.

41
Q

Fuel flow process

A

The fuel boost pump draws fuel from the unpressurized fuel cells to the engine. The fuel then flows through passages in the AGB to the fuel filter. Filtered fuel flows through a cored passage in the AGB to the HMU vane pump (high pressure). The HMU meters fuel in response to the following control inputs; T2, P3, ECU or DEC trim signal, LDS, PAS and Ng. Metered fuel is routed to the oil cooler by an external hose, and then to the ODV. The ODV provides main fuel flow to the 12 fuel injectors during start and normal operation. If the fuel filter becomes clogged, it is bypassed and the indicator button will pop. The #1 FUEL FLTR BYPASS indicator in the cockpit will illuminate.

42
Q

The fuel boost pump is an engine-mounted, …………….-type pump. It is not ………………….

A

The fuel boost pump is an engine-mounted, suction-type pump. It is not self-priming.

43
Q

The fuel system consists of what 8 parts?

A

The fuel system consists of the overspeed and drain valve (ODV) manifold, main fuel manifold, fuel injectors, fuel boost pump, fuel pressure sensor, HMU, ODV, and fuel filter.

44
Q

Why does the fuel system operate on negative pressure?

A

It assures that the airframe fuel supply system is under negative pressure, lessening the potential of fire in case of fuel system damage.

45
Q

What happens when the fuel filter clogs?

A

Bypass indicator pops out, and the bypass valve opens

46
Q

How does the engine compensate for variable power demands from collective inputs?

A

The LDS increases/decreases fuel flow

47
Q

Metered fuel leaving the HMU is routed through the oil cooler and then to the ________.

A

Metered fuel leaving the HMU is routed through the oil cooler and then to the overspeed and drain valve.

48
Q

The 30 micron fuel filter provides absolute filtration for engine fuel prior to entering the ________.

A

The 30 micron fuel filter provides absolute filtration for engine fuel prior to entering the HMU.

49
Q

What are the parameters that influence fuel flow and variable geometry positioning?

A

The parameters that influence fuel flow and variable geometry positioning are T2, P3, and Ng.

50
Q

How is engine power adjusted with the ENG POWER CONT Levers in lockout?

A

Adjustment of the ENG POWER CONT levers adjusts the PAS to set the maximum power available.

51
Q

If alternator power is lost to the engine, will the DEC still remain functional?

A

Yes, it is also supplied from the AC airframe power.

52
Q

What does the HSP automatically prevent?

A

It prevents over temperature during engine starts by shutting down the engine.

53
Q

What system keeps the engines at an approximate equal torque?

A

The torque matching/load sharing system.

54
Q

Overspeed circuit and auto relight coordination

A

Overspeed is tripped and auto relight continues for 5 seconds

MTPC (21 decks)

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