15.16 Turboprop Engines (Level 1, 3 Questions)

Question 1

What is the most efficient power source for aircraft operating between 300 to 450 mph?
A. Turbojet
B. Turboprop with reduction gearbox
C. Piston engine

Answer 1

B. Turboprop with reduction gearbox

Question 2

How much of the total power produced can a turboprop engine extract?
A. 80%
B. 95%
C. 60%

Answer 2

B. 95%

Question 3

In a gas-coupled/free-power turbine, what connects the gas generator and the power turbine?
A. Drive shaft
B. Hydraulic system
C. Gas flow only

Answer 3

C. Gas flow only

Question 4

Which is NOT an advantage of a gas-coupled turbine?
A. Easier to start in cold weather
B. Propeller rpm can be kept low during taxiing
C. Propeller is directly connected to the compressor

Answer 4

C. Propeller is directly connected to the compressor

Question 5

What can the gas generator in a free-power turbine engine be used as?
A. A generator only
B. A fuel pump
C. An APU

Answer 5

C. An APU

Question 6

What is mechanically connected in a gear/direct-coupled turbine?
A. Only the propeller and gearbox
B. Compressor and reduction gearbox
C. Gas flow only

Answer 6

B. Compressor and reduction gearbox

Question 7

Why does a gear/direct-coupled turbine require a complex propeller control system?
A. To increase engine temperature
B. To adjust propeller pitch for power requirements
C. To increase vibration

Answer 7

B. To adjust propeller pitch for power requirements

Question 8

What must change if the fuel flow changes in a direct-coupled turbine engine?
A. Turbine speed
B. Propeller pitch
C. Compressor pressure

Answer 8

B. Propeller pitch

Question 9

What is the function of the reduction gearbox in a turboprop engine?
A. Increase propeller rpm
B. Reduce engine rpm to a usable propeller rpm
C. Change direction of airflow

Answer 9

B. Reduce engine rpm to a usable propeller rpm

Question 10

What type of gears are used for larger torque reductions?
A. Helical gears
B. Spur gears
C. Epicyclic gears

Answer 10

C. Epicyclic gears

Question 11

What material are reduction gearbox gears typically made from?
A. Cast iron
B. High-quality alloy steel forgings
C. Carbon fiber

Answer 11

B. High-quality alloy steel forgings

Question 12

What are the two main types of reduction gears?
A. Bevel and worm gears
B. Planetary and helical gears
C. Parallel spur gear and epicyclic

Answer 12

C. Parallel spur gear and epicyclic

Question 13

What is a disadvantage of straight-cut spur gears?
A. They are expensive to cut
B. They are noisy
C. They are not efficient

Answer 13

B. They are noisy

Question 14

What is an advantage of helical gears over straight-cut gears?
A. Higher friction
B. Louder operation
C. Quieter operation

Answer 14

C. Quieter operation

Question 15

In an epicyclic gear system, what drives the planet gears?
A. Fixed ring gear
B. Propeller
C. Sun gear

Answer 15

C. Sun gear

Question 16

In a fixed annulus arrangement, the propeller rotates in what direction compared to the power turbine shaft?
A. Opposite direction
B. Same direction
C. Stationary

Answer 16

B. Same direction

Question 17

In a rotating annulus arrangement, the propeller rotates in what direction compared to the power turbine shaft?
A. Same direction
B. Opposite direction
C. It does not rotate

Answer 17

B. Opposite direction

Question 18

What determines the reduction gear ratio in an epicyclic gear system?
A. Number of planet gears
B. Number of gear teeth
C. Number of gear stages

Answer 18

B. Number of gear teeth

Question 19

What can propeller overspeed cause?
A. Minor vibration
B. Engine efficiency increase
C. Extreme stress leading to total failure

Answer 19

C. Extreme stress leading to total failure

Question 20

How does the propeller balance engine power output?
A. By reducing rpm
B. By absorbing it using blade angles to airflow
C. By increasing fuel flow

Answer 20

B. By absorbing it using blade angles to airflow

Question 21

What operates the blade angle change mechanism?
A. Electric motor
B. Engine oil
C. Hydraulic fluid from APU

Answer 21

B. Engine oil

Question 22

What is the feathering angle of a propeller?
A. 45 degrees to rotation
B. 90 degrees to plane of rotation
C. 180 degrees to shaft

Answer 22

B. 90 degrees to plane of rotation

Question 23

What happens at the feathering angle?
A. Maximum thrust is generated
B. Propeller spins faster
C. No angle of attack, propeller stops

Answer 23

C. No angle of attack, propeller stops

Question 24

What system carries out blade feathering to avoid windmilling?
A. ADLS (Automatic Drag Limiting System)
B. ECU (Engine Control Unit)
C. Compressor bleed system

Answer 24

A. ADLS (Automatic Drag Limiting System)

Question 25

What is the purpose of the auto feather system? A. To increase thrust B. To prevent blade separation C. To feather the propeller if oil pressure fails

Answer 25

C. To feather the propeller if oil pressure fails

Question 26

Where is the feathering pump’s oil supply drawn from? A. APU tank B. Engine oil tank C. Fuel lines

Answer 26

B. Engine oil tank

Question 27

How many backup locking mechanisms are there for pitch locking? A. One B. Two C. Three

Answer 27

B. Two (Mechanical & Hydraulic)

Question 28

What does the propeller overspeed governor do at 105% speed? A. Increases blade pitch to decrease speed B. Stops the engine C. Turns off the propeller

Answer 28

A. Increases blade pitch to decrease speed

Question 29

What happens if a power turbine detaches from its shaft? A. The turbine slows down safely B. A cooling system activates C. The engine shuts off fuel supply to prevent overspeed

Answer 29

C. The engine shuts off fuel supply to prevent overspending

Question 30

What is the alpha range used for? A. Reversing on the ground B. Engine start C. Using engine power in flight

Answer 30

C. Using engine power in flight

Question 31

What is the beta range used for? A. Cruise flight B. Ground handling and reversing C. Take-off power

Answer 31

B. Ground handling and reversing

Question 32

What system do modern turboprops use to control both engine and propeller? A. Single-lever throttle B. Manual override C. Dual FADEC system

Answer 32

C. Dual FADEC system

Question 33

What is the spinner’s function? A. Increase airflow through the engine B. Reduce drag by enclosing dome and barrel C. Support fuel nozzles

Answer 33

B. Reduce drag by enclosing dome and barrel

Question 34

What happens to the propeller when the engine is shut down in flight? A. It stops B. It feathers C. It reverses

Answer 34

B. It feathers

Question 35

What allows the propeller to be unfeathered in flight? A. Auto feather system B. FADEC override C. Feathering system

Answer 35

C. Feathering system

Question 36

Where are the engine and propeller control levers mounted? A. Overhead panel B. Pilot’s armrest C. Centre pedestal

Answer 36

C. Centre pedestal

Question 37

In single-lever control, when rpm reaches a set point, what takes over control? A. Pilot throttle input B. Propeller brake C. Fuel control unit

Answer 37

C. Fuel control unit

Question 38

Dual-lever controls are typically found on engines with what configuration? A. Gear-coupled turbines B. Piston engines C. Free turbine

Answer 38

C. Free turbine

Question 39

What does the power lever schedule during reverse thrust in dual-lever control? A. Oil pressure only B. Fuel and blade angle C. Propeller governor setting

Answer 39

B. Fuel and blade angle

Question 40

What does the propeller lever directly control? A. Feathering valve B. Engine oil pressure C. PCU for rpm selection

Answer 40

C. PCU for rpm selection

Question 41

What does the control lock prevent? A. Engine overspeed B. Propeller blade angle change C. Excessive flutter of control surfaces on the ground

Answer 41

C. Excessive flutter of control surfaces on the ground