Powerplant

Question 0

Max Takeoff Power SHP

Answer 0

5071 SHP

Question 1

Normal Takeoff Shaft Horsepower

Answer 1

4,580 SHP

Question 2

Describe Nl

Answer 2

Low pressure axial compressure

Question 3

Describe Nh

Answer 3

High pressure centrifugal compressor

Question 4

What is the engine accessory gear box driven by?

Answer 4

high pressure (Nh) compressor rotor

Question 5

What components are on the engine accessory gear box?

Answer 5

Fuel Metering Unit (FMU)
Oil Pump
DC Starter-Generator
Permanent Magnet Alternator (PMA)

Question 6

What drives the propeller reduction gear box?

Answer 6

power turbine shaft

Question 7

How much extra power does the FADEC deliver when the power levers are over-traveled past the rating detent?

Answer 7

25%

Question 8

What components are mounted on the propeller reduction gear box?

Answer 8

Hydraulic Pump (main engine-driven pump)
AC Generator
Pitch Control Unit (PCU)
Propeller Overspeed Governor (POG)

Question 9

Maximum reverse thrust SHP

Answer 9

1500 SHP

Question 10

Describe the FMU.

Answer 10

The electro-mechanical Fuel Metering Unit is mounted on and driven by the engine accessory gearbox and controls fuel flow to the engine based on signals from the FADEC.

Question 11

How many fuel pumps are in the FMU?

Answer 11

two integral engine driven fuel pumps; a low pressure pump and a high pressure pump

Question 12

What are the functions of the FADEC?

Answer 12

controls engine fuel flow
controls various engine bleed valves to prevent compressor surges and stalls
prevents engine overspeed
controls automatic start and shutdown
supplies voltage to the Propeller Electronic Control (PEC)
detects and indicates powerplant faults

Question 13

Electrical power source for the FADEC

Answer 13

Permanent Magnet Alternator (PMA) driven by the accessory gearbox when Nh is above 20%; essential DC bus initially

Question 14

Describe how the FMU uses fuel pumps to meter fuel.

Answer 14

The low pressure pump receives low pressure fuel from the fuel tank boost ejector pump and sends it to the heater/filter element. After being heated and filtered the fuel is routed to the high pressure pump which sends it to the metering valve and then to the engine fuel nozzles. A portion of the high pressure fuel returns to the fuel tank to provide the motive flow necessary for the operation of the fuel tank ejector pumps.

Question 15

Describe a FADEC critical fault.

Answer 15

FADEC will automatically respond to a critical fault with either a power stabilization to flight idle or engine shutdown.

Question 16

Describe a FADEC Cautionary Fault.

Answer 16

condition that requires caution when applying control inputs; may result in either the necessity to reposition power levers to maintain symmetrical torque, or power lever movement that causes engine surge

Question 17

Describe a FADEC Advisory Fault.

Answer 17

automatically accommodated by the FADEC and does not result in the illumination of warning lights or caution lights; transmits fault code to the Engine Monitoring Unit (EMU)

Question 18

When does the Automatic Takeoff Power Control System (ATPCS) automatically arm?

Answer 18

both power lever angles “high” and torque on both engines at least 50%

Question 19

An uptrim condition is indicated in the cockpit by:

Answer 19

“UPTRIM” message on ED
change in power rating from NTOP to MTOP on ED
change in torque bug position from NTOP to MTOP

Question 20

A power uptrim will occur when either of the following conditions exist:

Answer 20

torque on the failed engine falls below 25% with the power levers in the RATING detent and MTOP not selected
power turbine speed (NPT) falls below 80% with the power levers in the RATING detent and MTOP not selected

Question 21

Describe the Nh overspeed protection.

Answer 21

powerplant has an independent overspeed protection circuitry (dual channel) built into the FADEC which has the capability to cut off fuel flow to the engine through the Fuel Shutoff Solenoid (inside the FMU)

Question 22

Propeller system components

Answer 22

Propeller Electronic Control (PEC)
Pitch Control Unit (PCU)
Propeller Overspeed Governor Unit (POG)
Auxiliary Feathering Pump
Automatic Propeller Synchrophase System

Question 23

Describe the PEC.

Answer 23

The Propeller Electronic Control is a dual channel microprocessor based controller which uses inputs from the airplane, propeller control system sensors, and the engine control system to control propeller pitch and speed. The PEC is soft mounted aft of the propeller reduction gearbox and performs a number of safety functions.

Question 24

Describe the functions of the PEC.

Answer 24

Autofeather
Automatic Underspeed Propeller Control
initiates power UPTRIM command to the FADEC

Question 25

Describe the PCU.

Answer 25

The Pitch Control Unit is a hydromechanical device that interfaces with the propeller to meter high pressure engine oil to a two stage servo valve mounted on the PCU which controls propeller speed by directing the flow of high pressure oil into the fine pitch or course pitch chambers of the prop pitch change cylinder as directed by the PEC. It also controls the minimum blade pitch that can be obtained in flight.

Question 26

Describe the POG.

Answer 26

The Propeller Overspeed Governor unit is an independent mechanical system used to limit the propeller speed in case of a propeller overspeed malfunction; incorporating a high pressure pump (driven by the reduction gearbox) to provide the PCU with high pressure oil from the engine gearbox. The Governor is a flyweight design, driven directly from the drive gear of the pump.

Question 27

Describe the Auxiliary Feathering Pump.

Answer 27

The Auxiliary Feathering Pump consists of a 28 volt DC electrical motor driving an external gear pump which is mounted on the aft side of the propeller reduction gearbox and provides a secondary source of oil pressure for feather the propeller. The pump is automatically activated when autofeather occurs and is manually activated when alternate feather is selected.

Question 28

Describe the Propeller Synchrophase System.

Answer 28

When the speeds of both propellers are within a predetermined difference of one another in flight, the PEC automatically enters a synchrophase mode to reduce propeller noise. The phase angle is calculated by timing the differences between the master prop (left) and slave prop (right) Magnetic Pickup Unit signals over a complete propeller revolution. Does not operate during takeoff.

Question 29

When does the autofeather system arm?

Answer 29

autofeather system select ON

torque of both engines exceeds 50% and both power levers are advanced beyond a 60 degree angle.

Question 30

When does the autofeather system trigger?

Answer 30

torque of the failed engine falls below 25% for at least three seconds

Question 31

How long does the Auxiliary Feathering Pump activate after an autofeather?

Answer 31

approximately 30 seconds

Question 32

Explain how the POG works.

Answer 32

incorporates hydraulic and electronic section to reduce high pressure oil supply when prop speed exceeds 1071 rpm and/or uses FADEC Np overspeed circuitry to signal FMU to reduce amount of fuel being supplied to the engine when prop speed reaches 1122 rpm

Question 33

Describe the engine ignition system.

Answer 33

consists of one dual channel exciter unit and two igniter plugs in the combustion chamber; controlled by FADEC

Question 34

Name and describe the start malfuntions.

Answer 34

Hot start - ITT exceeds 920C
No light off - engine does not light within 16 seconds of fuel intro
Hung start - Nh does not reach 50% within 70 seconds
No starter cutout - START light remains illuminated (QRH)
Starter Failure - SELECT light remains illuminated (QRH)

Question 35

Describe the difference between an air start and ground start.

Answer 35

Air start:
both igniters are activated
FADECs auto abort circuits are disabled
FADECs automatic ITT limiting feature is disabled

Question 36

When does the START SELECT switch automatically center itself during at start?

Answer 36

Nh reaches approximately 50%

Question 37

How is engine oil cooled?

Answer 37

automatic routing of oil through an air cooled oil cooler (cooler door located on the underside of the engine nacelle)

Question 38

1 or #2 ENGINE OIL PRESS warning light

Answer 38

engine oil pressure below 44 psi

Question 39

1 or #2 ENGINE FADEC FAIL warning light

Answer 39

FADEC has malfunctioned

Question 40

1 or #2 ENG FUEL PRESS caution light

Answer 40

pressure at engine driven fuel pump inlet is low, ejector pump failure or loss of motive flow to the ejector pump

Question 41

1 or #2 ENG FADEC caution light

Answer 41

FADEC sensed a condition that requires caution when applying control inputs

Question 42

1 or #2 PEC caution light

Answer 42

PEC senses a beta mode malfunction

Question 43

Describe the autofeather process.

Answer 43

Following a 3-second delay, the propeller of the failed engine will then automatically feather. Immediately after the autofeather of the failed engine’s propeller is initiated, the autofeather system automatically disarms and the AF/ARM advisory message on the ED disappears. The disarming of the system prevents any possible occurrence of a dual autofeather. The associated Auxiliary Feathering pump is activated for approximately 30 seconds to assure adequate oil pressure is available to feather the failed engines propeller. The associated Alternate Feather switchlight (guarded) on the Propeller Control panel will illuminate indicating activation of the Auxiliary feather pump.
The Autofeather system then sends an Np underspeed cancel signal to the failed engines FADEC preventing the FADEC from increasing NH in an attempt to maintain propeller speed as the feathering propeller speed decreases below 660 rpm.
The Auxiliary feathering pump also serves as a backup source of oil pressure to the propeller pitch-change mechanism in the event of a loss of engine oil pressure. The pump is supplied with oil from an auxiliary oil reservoir built into the case of the propeller reduction gearbox.