15.16

Question 1

turboprop best for operating at what speed

Answer 1

483-725kmh / 300-450mph

Question 2

What height is turboprop good for

Answer 2

6000m / 20000ft +

Question 3

In cruising what makes turboprop better then turbo jet

Answer 3

Propulsion efficiency is constant in turboprop whereas it increases in turbojet as airspeed increases

Question 4

How much power can turboprop extract

Answer 4

95%

Question 5

What’s the core engine known as in turboprop

Answer 5

Gas generator or producer

Produces high velocity gases that provide energy to drive the power turbine

Question 6

What connection is there in a free power turbine and gas generator

Answer 6

No mechanical connection only a gas flow connection

Question 7

Advantages of free power turbine

Answer 7

Vibration not directly transmitted to the gas generator

Easier to start , especially in cold weather

Propeller held at low rpm during taxing

Can use a propeller brake to stop propeller movement during aircraft loading when shutdown not desired

Question 8

How are gear-direct coupled turbines different to free power

Answer 8

Extra discs that are mechanically connected to compressor and reduction gearbox

Question 9

Why does the propeller pitch and fuel flow need to be coordinated

Answer 9

So if fuel flow changes then propeller pitch must change to maintain a constant speed

Question 10

What’s the function of the reduction gear assembly

Answer 10

Reduce high rpm from the engine to a propeller rpm

Needs to be maintained without exceeding the maximum propeller tip speed (SoS)

Question 11

When would you use an epicyclic gear

Answer 11

Larger high torque reductions

Question 12

2 types of reduction gears

Answer 12

Parallel spur and epicyclic

Question 13

Advantage and disadvantage of straight cut parallel spur gear

Answer 13

Easy to cut and have lowest frictional losses

Very noisey

Question 14

Helical cut parallel spur gear advantage and disadvantage

Answer 14

Quieter

Less efficient in transmission of power

Question 15

What gear wheel does a epicyclic reduction gear use

Answer 15

Planet gears

Question 16

How is epicyclic reduction gear ratio calculated

Answer 16

Dividing number of driven teeth by number is of driving teeth

Question 17

What direction does the propeller shaft drive in rotating annulus

Answer 17

Opposite direction of rotation to the power turbine shaft

Question 18

What direction does the propeller shaft drive in a fixed annulus

Answer 18

Same direction of rotation as the power turbine shaft

Question 19

What speed does the propeller rotate in fixed annulus

Answer 19

At a speed dependent on the reduction gear ratio

Question 20

What does the fadec system control

Answer 20

Engine and propeller

Question 21

What shape is the spinner

Answer 21

Cone-shaped configuration that mounts on the propeller and encloses he some and barrel to reduce drag

Question 22

What does the feathering system do

Answer 22

Feathers propeller when engine is shut down and unfeather if engine needs to be started

Question 23

On multi-engine aircraft where is the lever for number one engine

Answer 23

On the left

Question 24

What uses a single thrust lever

Answer 24

Gear couple engine

Question 25

What lever does a turbo propeller engine use

Answer 25

Dual lever if it has a free turbine

Question 26

What does the thrust lever do

Answer 26

Schedule fuel flow from idle - takeoff

Blade angle from 20 to -20 degrees (BETA / ground operating range)

Question 27

What does the control lock do

Answer 27

Ensures aircracft control surfaces do not flutter excessively on the ground with the engines running

Question 28

What does the propeller lever do

Answer 28

Selects the required rpm by applying or releasing pressure on the governor control spring

Question 29

What does overspeed cause

Answer 29

Extreme stress to the propeller and engine and can lead to rapid and total failure

Question 30

How low can reduction gearing be

Answer 30

Low as 1:22

One revolution = 22 engine rotations

Question 31

What is the feathering angle

Answer 31

90 degrees to the plane of rotation

Blade chord is in line with the airflow

Question 32

What does the automatic drag limiting system do

Answer 32

Feathers the propeller if the oil supply fails to avoid it from windmilling

Question 33

When does a propeller overspeed governor activate

Answer 33

Propeller speed exceeds 105% governor dumps oil pressure to increase blade angle

Question 34

What’s the governor a safety device for

Answer 34

Operate if normal propeller governor and fuel control overspeed governor fail to contain the engine speed

Question 35

What happens in turbine shaft failure

Answer 35

Mechanical system in place to immediately shut off the engine-metered fuel supply in event of turbine shaft failure