Propeller Pitch Control

Question 1

How many propellers type

Answer 1

2 , push and pull tractor

Question 2

What 3 methods can you use to change controllable and constant speed propellers

Answer 2

Hydraulic , mechanical or electrical

Question 3

In a multiple engine aircraft why is there a facility to shut down engine propeller

Answer 3

Be feathered to minimise drag

Question 4

Why does a large aircraft need reverse thrust

Answer 4

Facility for reverse thrust go shorten landing distance and help with taxing

Question 5

Propeller sub divisions

Answer 5

Fixed
Adjustable
Controllable
Constant speeding

Question 6

What does distance breaking do

Answer 6

Move propeller to very low pitch on landing

Question 7

Why do we distance break

Answer 7

For negative AoA and breaking force

Question 8

What does reverse pitch (power on) do

Answer 8

Offers resistance to rotation

Question 9

How does reverse pitch offer resistance

Answer 9

Moves propeller blades to make angle negative

Question 10

Where does the propellor move in engine failure

Answer 10

Feather in one step

Question 11

What are the pitch change mechanism categorised as

Answer 11

Moving piston & moving cylinder

Question 12

How does moving piston work

Answer 12

Attached to propeller blade lugs and it moves with cylinder

Question 13

What does a a balance weight do in a moving cylinder do

Answer 13

turns propeller in opposite direction

Question 14

In a single acting propeller what way does the oil pressure move

Answer 14

One direction

Question 15

In a single acting propeller what is movement in the opposite direction a result of

Answer 15

Spring force & moments of blades

Question 16

What direction does oil pressure move in single acting propeller for single acting aircraft

Answer 16

Direction of high pitch

Question 17

Where does spring move in single acting propellers for single engine aircraft

Answer 17

Spring moves towards low pitch

Question 18

Single acting propellers for multi - engine aircraft what happens in engine failure

Answer 18

Decrease in oil pressure and the blades move to high pitch

Question 19

What is high pitch

Answer 19

Coarse

Question 20

What is low pitch

Answer 20

Fine

Question 21

Which way is pitch change mechanism controlled

Answer 21

Both ways by oil pressure

Question 22

If the control valve is behind gearbox where is the oil transfer tubes a

Answer 22

2 tubes , one at the front and one back

Question 23

double acting propeller is connected by which what tubes

Answer 23

Coaxial tubes , one coarse and one fine

Question 24

What are the 3 names of propeller governor

Answer 24

Propeller governor
Constant speed unit
Propeller control unit

Question 25

What does a spur gear pump do

Answer 25

Positive operating pressure

Question 26

How is a propeller governor mounted

Answer 26

Mounted on and driven by the reduction gearbox

Question 27

What do centrifugal fly weights do

Answer 27

Oppose spring pressure and moves valve to coarser blade angle

Question 28

What is the purpose of saftey spring

Answer 28

Permanently set blades to fine pitch position in event of lever failure

Question 29

What are the flyweight position during on speed

Answer 29

Vertical

Question 30

What does vertical fly weights do

Answer 30

Maintain the pilot value in position that allows no oil to flow into or out of governer assembly by use of HYDRAULIC LOCK

Question 31

During on speed what does the spur gear pump increase to

Answer 31

250psi

Question 32

Underspeed condition

Answer 32

More tension forces pilot valve down

Question 33

Overspeed condition

Answer 33

Lower rpm causes centrifugal force on flyweight to lift pilot valve up

Question 34

How is a change in power achieved

Answer 34

Changes in torque

Question 35

What has greater range of pitch turboprop or piston engine

Answer 35

Turboprop

Question 36

Max speed in turboprop variable pitch propeller

Answer 36

450 mph

Question 37

GTE efficient at high rpm

Answer 37

8/10k RPM

Question 38

Propeller efficiency at low rpm

Answer 38

1-1.2k RPM

Question 39

How does propeller speed get matched to engine

Answer 39

Reduction gearbox

Question 40

Reduction gearbox ratios

Answer 40

6:1 & 20:1

Question 41

What engine is a compounded engine

Answer 41

Twin spool

Question 42

Disadvantage of compounded engine

Answer 42

Only suitable for large engines

Question 43

Disadvantage of direct coupled engine

Answer 43

Complex connection between throttle and propeller control

Question 44

Why is a compounded engine free from surge

Answer 44

It has a constant rpm

Question 45

Disadvantage to free power turbines

Answer 45

More intensive on pilot as he needs to constantly maintain parameters

Question 46

Advantage of free power turbine

Answer 46

Independent control of engine and propeller and they operate at optimum speed

Question 47

For overspeed where does the pilot pull the lever

Answer 47

Rearwards

Question 48

Reasons for overspeed

Answer 48

Aircraft into dive Speeder spring force reduced on fly-weights Pilot increase fuel flow by moving throttle forward

Question 49

Why would we unfeather an engine during flight

Answer 49

For engine restart

Question 50

How do we unfeather a propeller

Answer 50

Move it to a fine pitch

Question 51

What’s provides a reserved of pressure to turn blades when unfeathering

Answer 51

Unfeathering accumulator

Question 52

When are centrifugal latches used

Answer 52

At engine shut down to stop piston moving and lock it into a fine pitch

Question 53

What’s shaft horse power

Answer 53

Power available from engine at propeller driveshaft

Question 54

What is equivalent shaft horsepower

Answer 54

Residual power from engine exhaust plus SHP

Question 55

At static what is 1hp equivalent to in thrust

Answer 55

2.5lbs

Question 56

What do turboprop gas generators run at

Answer 56

100% rpm or near

Question 57

How is FFPS operated

Answer 57

Oil pressure which is controlled electronically in cockpit

Question 58

FFPS two positions

Answer 58

Engaged and withdrawn

Question 59

What does the electro hydraulic stop coarsen

Answer 59

Pitch of blade preventing propeller from drifting below flight fine pitch should FFPS fail

Question 60

When does the microswitch energise and engage electro-hydraulic stop

Answer 60

Blade angle reduces more then 2 degrees below FFPS

Question 61

On direct control of blade angle what does the engine follow

Answer 61

Propller

Question 62

Direct control of fuel flow

Answer 62

Propeller follows engine speed

Question 63

What’s the purpose of the CSU

Answer 63

Keep propeller rpm constant on free power turbines

Question 64

What are the 3 reasons for limit fine pitch

Answer 64

Engine failure Propeller control Control unit failure

Question 65

What does FFPS do

Answer 65

Ensures adequate thrust given when needed in flight operations

Question 66

What does constant speeding mean

Answer 66

Governer is regulating the speed of propeller within certain rpm range

Question 67

Where is resetting of beta valve done

Answer 67

Mechanical feedback via beta ring

Question 68

Is propeller governor effective in beta range

Answer 68

No

Question 69

How is beta range controlled

Answer 69

Power lever

Question 70

What does overspeed governer provide

Answer 70

Pcu with high pressure engine oil to change pitch of propeller Governor prevents over speeding

Question 71

What type of propeller uses twin lever control

Answer 71

Single acting propeller

Question 72

What does the conditioning lever do in twin lever control

Answer 72

Selects propeller rpm

Question 73

What does the power lever control in twin lever control

Answer 73

Controls engine power

Question 74

What does a ground fine pitch stop do

Answer 74

Keeps blades at zero position for starting and initial acceleration

Question 75

When is feathering used automatically

Answer 75

During take off & cruise

Question 76

Lever movement C-D

Answer 76

When fuel flow increases , rpm increases to maintain optimum blade angle

Question 77

Lever movement D-E when is more rpm needed

Answer 77

During take off

Question 78

What’s the beta range power lever positions

Answer 78

Idle and maximum reverse

Question 79

Advantages of beta range

Answer 79

Reduce landing roll & brake wear

Question 80

How does beta range help while aircraft on ground

Answer 80

Improve manoeuvrability on ground and reversing during taxiing

Question 81

Disadvantages of beta range

Answer 81

Complicated control system and increased blade damage

Question 82

When is engine cooling reduced

Answer 82

When in reverse pitch

Question 83

Where is hydromechanical PCU mounted

Answer 83

Reduction gearbox

Question 84

How does pcu control pitch of propeller

Answer 84

Directing oil either side of pitch change piston through a dual concentric beta tube

Question 85

How much % more power to engine does uptrim give

Answer 85

10%

Question 86

What condition is auto feather used

Answer 86

Take off only

Question 87

What % of torque triggers uptrim

Answer 87

Below 25%

Question 88

What speed triggers uptrim

Answer 88

Below 80%

Question 89

When is uptrim triggered

Answer 89

When max take off not set & one engine automatically feathers which uptrims other engine

Question 90

What do you push to turn off autofeather

Answer 90

Push autofeather switch light off

Question 91

Where do you push power lever to turn off autofeather

Answer 91

One or both power levers to idle

Question 92

When is auto feather disarmed

Answer 92

Both engine torques drop below 50%