Fatigue and Stress | Constant Speed Propeller

Question 1

The constant speed propeller is based on the idea that the power available depends not only on the efficieny of the propeller, but also the ___

Answer 1

shaft power coming from the engine

Question 2

The shaft power coming from the engine is ___ proportional the the RPM

Answer 2

directly

Question 3

For a given throttle setting, the engine RPM depends on the load on the ___

Answer 3

crankshaft

Question 4

Aerodynamic torque comes from the ___ component of aerodynamic force exerted on the propeller in the ___ __ ___, acting through a moment arm to the shaft

Answer 4

plane of rotation, resistive

Question 5

The constant speed propeller changes the pitch automatically to keep the engine RPM ___

Answer 5

constant

Question 6

A constant speed propeller can have its ___ adjusted for varying conditions

Answer 6

pitch

Question 7

Most constant speed propellers are ___ operated with a centrifugal ___ operating a control valve that lets oil in to make the pitch ___ or releases it for ___ pitch

Answer 7

coarser, fine

Question 8

A ___ pitch is best for takeoff

Answer 8

fine

Question 9

As forward speed increases on takeoff, the pitch angle is ___ by the governor to stop the engine from overspeeding

Answer 9

increased

Question 10

For full speed in the cruise, a ___ pitch is selected and the engine speed can be ___ to a more comfortable level

Answer 10

coarse reduced

Question 11

A double acting propeller users ___ ____ to move the blades towards both fine and coarse pitch angles

Answer 11

oil pressure

Question 12

A single acting propeller uses ___ ___ to move the blades towards the smaller pitch angle. If the engine fails, the blade ___ automatically to produce ___ ___

Answer 12

oil pressure feather minimum drag

Question 13

Engine overload when changing power is avoided by increasing the __ ___ prior to increasing the ___ __

Answer 13

propeller RPM, manifold pressure

Question 14

If the engine oil pressure is lost, an ___ ___ can be used to feather the propeller only

Answer 14

electrical pump

Question 15

The feathering pump is an electrically driven oil pump that suppliers the propeller with oil under pressure when the ___ ___ ___ ___.

Answer 15

engine is shut down

Question 16

Unfeathering, with an engine failed, is done with an pressurised oil from an ___ or ___ ___.

Answer 16

accumulator or electric pump

Question 17

The extremes of pitch in flight is limited by ___ ___

Answer 17

mechanical stops

Question 18

In flight, the ___ pitch stop can be varied to prevent a sudden massive selection of fully fine.

Answer 18

fine

Question 19

On the ground, the ___ pitch stop can be removed to allow the prop to go to ground fine and reverse pitch.

Answer 19

fine

Question 20

The superfine pitch setting establishes ___ blade angle

Answer 20

zero

Question 21

Early turboprop engines used a ___

Answer 21

reduction gearbox

Question 22

Most modern turboprops use a ___

Answer 22

free turbine

Question 23

A free turbine is (not) connected to the main spool of the engine.

Answer 23

not

Question 24

A superfine pitch can be used to produce a great deal of extra drag in flight, called ___

Answer 24

discing

Question 25

The job of the propeller is to convert the ___ delivered form the rotation speed of the crankshaft into ___

Answer 25

torque, thrust

Question 26

A crankshaft or power turbine runs at so high a speed that ___ ___ is needed to drive a transmission

Answer 26

reduction gearing

Question 27

___ or ___ reduction gears are used on radial engines

Answer 27

Epicyclic planetary

Question 28

___ reduction gearing is generally used with in-line engines

Answer 28

spur

Question 29

___ ___ will support the propeller shaft

Answer 29

Roller bearings

Question 30

A ___ or ___ ___ ___ transfers propeller thrust to the airframe, though ___ ___ and a ___ ___ may be used instead.

Answer 30

ball, roller thrust bearing, plain bearings, thrust washer

Question 31

Lubrication is normally from the __ ___ system

Answer 31

engine oil

Question 32

The torquemeter indicates the twisting force of the ___ against the ___

Answer 32

engine, transmission

Question 33

Part of the ___ ___ can be used to measure the power output because ___ ___ is generated when helically cut gears are used to transfer power from one shaft to another

Answer 33

reduction gearing, axial thrust

Question 34

The amount that the gears move when they rotate is proportional to the ___ ___

Answer 34

torque applied

Question 35

Turbine engines in turboprops have a ___ and ___ torque output

Answer 35

smooth uniform

Question 36

Torque is a measure of the ___ being used

Answer 36

power

Question 37

Torque is measured between the ___ and the __ __

Answer 37

engine reduction gearbox

Question 38

Torque can be expressed in ___ ___, ___ ___, or ___ ___, ___ ___, or ____ ____

Answer 38

Newton Metres, brake horsepower, shaft horsepower, inch pounds, or foot pounds

Question 39

Torque may be shown on a torque gauge as a ___

Answer 39

percentage

Question 40

Power = ___ x ___

Answer 40

Torque x RPM

Question 41

Having the torquemeter on the ___ shaft allows the engine torque to be closely monitored.

Answer 41

output

Question 42

Manifold pressure is measured on the ___ side of the engine

Answer 42

input

Question 43

Manifold pressure is a ___ of engine power, whereas torque is a ___

Answer 43

predictor measurement

Question 44

Changes in __ or ___ are the only way of determining whether the engine is meeting its specification

Answer 44

N1 TOT

Question 45

An electronic torquemeter uses the same probe and phonic wheel system as an ___ ___ indicator, on two concentric shafts

Answer 45

engine RPM

Question 46

The torque shaft is connected to the ___ and the ___ ___, whereas the reference shaft is only connected to the ___

Answer 46

engine, reduction gearbox, engine

Question 47

There is a ___ wheel at the forward end of each shaft that rotates past the pickup to produce an _C voltage

Answer 47

toothed AC

Question 48

As power changes, so does the ___ relationship between the voltages from the toothed wheels, in proportion to the power used.

Answer 48

phase

Question 49

___ can be used to force the blades into ___ their angle of attack when power is lost

Answer 49

Counterweights increasing power

Question 50

With counterweights, loss of oil pressure ___ the blades

Answer 50

feathers

Question 51

Using ___ RPM in the cruise with a ___ manifold pressure will reduce fuel consumption

Answer 51

lower higher

Question 52

Using too high of a manifold pressure against too low of an RPM makes the engine work ___ ___ and ___ ___

Answer 52

too hard, risks detonation

Question 53

The constant speed range is (not) maintained at very low power settings

Answer 53

not

Question 54

As the throttle setting is reduced, the CSU senses a reduction in RPM and ___ the propeller. With the PCU piston coming into contact with the fine pitch stop in the cyclinder and the blade angle ___

Answer 54

fines, remaining constant

Question 55

The flight fine pitch stop is withdrawn when ___

Answer 55

on the ground

Question 56

The travel of the PCU piston in the coarse pitch direction is limited, either to a maximum to prevent ___ or to feather the blade angle, typically about __ degrees

Answer 56

overtorquing 85

Question 57

Windmilling is the phenomena where The airflow creates a ___ ___, causing it to rotate in the ___ direction

Answer 57

lifting force, normal

Question 58

The finer the pitch of the propeller blades, the ___ the windmilling rotation

Answer 58

faster

Question 59

To feather the propeller following an engine failure, the RPM lever is moved through the ___ position, and the throttle is ___

Answer 59

low, closed

Question 60

Without a feathering system, the blades will tend to move towards the __ blade angle, using the centrifugal turning moment or spring forces.

Answer 60

smallest

Question 61

___ stops prevent the blades moving past the feathering position

Answer 61

feathering

Question 62

In turboprops, the power levers control the ___ and the prop levers control the ___

Answer 62

torque RPM

Question 63

In a turboprop, higher oil pressures create a ___ pitch and ___ RPM

Answer 63

flatter higher

Question 64

The turboprop uses ___ propeller governors:

Answer 64

3

• Primary
• Overspeed
• Fuel-topping

Question 65

The FCU is the ___

Answer 65

Fuel Control Unit

Question 66

The ___ and ___ work together to keep the propeller RPM constant over a range of power settings

Answer 66

FCU and turbine governor

Question 67

As you push the levers forward, the FCU sends more fuel to the ___ ___ which makes the turbine spin ____. This is sensed by the governor which makes the blades ___ their pitch to absorb the extra energy and provide increased thrust.

Answer 67

compression chambers faster coarsen

Question 68

The primary governor works using ___

Answer 68

Flyweights

Question 69

If the engine RPM decreases, the flyweights on the primary governor ___ and are drawn ___, allowing ___ oil in to ___ the pitch.

Answer 69

slow down, inwards, more, reduce

Question 70

The overspeed governor is a relief valve that ___ the blade angle automatically if the primary governor fails.

Answer 70

increases

Question 71

The fuel-topping governor also prevents ___, by adjusting the ___ ___

Answer 71

overspeeding fuel flow

Question 72

Changes in power output are not directly related to engine speed but to the ___ ___ ___, which is determined by the ___ ___

Answer 72

turbine inlet temperature, fuel flow

Question 73

Increased fuel flow will ___ the turbine inlet temperature. The absorbed energy is transmitted to the propeller as ___, ___ the blade angle to maintain a constant RPM

Answer 73

increase, torque, increase

Question 74

Negative torque occurs when the propeller spins ___ than the reduction gear and drives the engine instead of the other way around

Answer 74

faster

Question 75

Negative torque may happen when:

Answer 75

• Fuel flow is interrupted
• Gust loads on the prop
• During descent with high compressor bleeds at low power
• Shutdown

Question 76

If the negative torque exceeds the maximum limit of the Negative Torque Signal, a safety coupling will ___

Answer 76

disengage the reduction gear from the engine

Question 77

An autofeather system is armed during ___

Answer 77

takeoff and landing

Question 78

The beta range is the __ range of the power lever that is accessed through a gate

Answer 78

aft

Question 79

In the beta range, the propeller blade angle is not controlled by the RPM level through the governor, but by the power lever through an ___ ___ ___ system

Answer 79

oil pressure control

Question 80

The beta value bypasses the ___ ___ to send more oil to the hub, and allows the power lever to control only propeller pitch in the beta range

Answer 80

primary governor

Question 81

Low pitch stops/hydromechanical locking devices stop the propeller entering the ___ ___ or ___ ___ in the cruise

Answer 81

beta range, reverse pitch

Question 82

In reverse range, the power lever controls ___ and ___

Answer 82

pitch and torque

Question 83

In the alpha range, the power output and propeller RPM are controlled by ___

Answer 83

one lever

Question 84

The condition lever provides ___ in the ___

Answer 84

residual control, alpha range

Question 85

When the power lever is moved aft of ground idle, the pitch reduces to ___, then is ___ for reverse thrust

Answer 85

zero, reversed

Question 86

Engine power will ___ as negative pitch is applied

Answer 86

increase

Question 87

CSU means ___

Answer 87

Constant Speed Unit

Question 88

CSUs can be matched to the exact speeds automatically with a ___ or ___

Answer 88

synchroniser synchroscope

Question 89

A ____ on each engine generates a signal that is proportional to within 100 RPM of the engine speed.

Answer 89

tachogenerator

Question 90

A ____ measures the difference in alternator output frequencies

Answer 90

syncroscope

Question 91

A typical synchronisation system will consist of ___

Answer 91

• Phonic wheel
• Magnetic pickup
• Control box, to compare the two signals

Question 92

The engine with the ___ voltage/frequency determines which way the actuator will rotate

Answer 92

higher

Question 93

Synchronisation will (not) take place on takeoff or landing

Answer 93

not

Question 94

___ allows you to set relative positions of the propeller blades

Answer 94

Synchrophasing

Question 95

A synchroscope for a twin engine aircraft measures the ___ of both ___

Answer 95

difference in output frequencies of both alternators