Module 17.6 Propeller maintenance

Question 1

When working with propellers three different types of balancing are of importance, what are these?

Answer 1

• Static
• Dynamic
• Aerodynamic

Question 2

What are static and dynamic imbalances caused by?

Answer 2

Unequal mass distribution

Question 3

Why is aerodynamic balancing done?

Answer 3

Ensure each blade delivers the same thrust

Question 4

A body is in static balance when?

Answer 4

Centre of gravity lies at the centre of rotation

Question 5

Static balance is checked in what planes?

Answer 5

Vertical and horizontal

Question 6

Where is static balancing done?

Answer 6

Off of the aircraft

Question 7

What is dynamic balancing?

Answer 7

Balancing the moment to reduce the moment of imbalance

Question 8

How is the dynamic balancing checked?

Answer 8

While the engine is running

Question 9

When is an object in aerodynamic balance?

Answer 9

When the aerodynamic forces acting on the blades result in no periodic vibrations in the mountings. This means each blade will produce equal thrust

Question 10

What does vibration caused by the blades being unbalanced aerodynamically get worse with?

Answer 10

Becomes worse with increasing pitch and thrust

Question 11

Aerodynamic correction factor is either done for what?

Answer 11

Thrust or torque

Question 12

What will the blade be marked with for ACF, thrust and torque?

Answer 12

Thrust - T
Torque - Q

Question 13

Aerodynamic balancing is only necessary for what propellers?

Answer 13

High performance

Question 14

What is the universal blade protractor used to determine?

Answer 14

Used to measure the angle to a reference station. Done to ensure all blades are properly adjusted

Question 15

Where is the reference station usually?(Universal Blade Protractor)

Answer 15

30 inch, 36 inch, 42 inch

Question 16

What is blade tracking?

Answer 16

Ability of one blade to follow the other in the same plane of rotation

Question 17

What are the two methods for checking blade tracking?

Answer 17

• Falt bench method
• Block or pointer method

Question 18

How far should the pencil lines be apart in the flat bench method?

Answer 18

3mm

Question 19

What should the tracking separation be in the block or pointer method?

Answer 19

+- 1/16 inch

Question 20

Airworthy damage limits are described where?

Answer 20

Within AMM chapter 61

Question 21

What methods can be used for inspecting the blades for damage?

Answer 21

• Visual
• Tap
• Dye penetrant
• Ultrasonic
• Eddy current
• Magnetic particle

Question 22

The use of what dyes is not recommended?

Answer 22

Visible dyes

Question 23

What 3 categories can the corrosion on the blade be classified into?

Answer 23

• Surface
• Pitting
• Intergranular

Question 24

What are composite and wood propellers susceptible?

Answer 24

Delamination

Question 25

Cracks in the paint are signs of what?

Answer 25

Flexural vibration

Question 26

Less significant damage on the trailing edge or on the blade of wood propellers can be filled with what?

Answer 26

Plastics

Question 27

How often should blades be inspected?

Answer 27

Every 100 hours or at annual check

Question 28

How must nicks be repaired?

Answer 28

Blending

Question 29

How much must the blend be on the TE and LE?

Answer 29

10 x depth of nick for the leading and trailing edges

Question 30

How much must the blend be on the blade face and back?

Answer 30

30 x the depth for the blade face and back

Question 31

What must the hub be checked for periodically?

Answer 31

Cracks and corrosion

Question 32

Damage on composites is classified as what?

Answer 32

Acceptable or unacceptable

Question 33

Sub-classification of damage may also be sub-divided as what?

Answer 33

- Skin perforated damage - Skin not perforated damage

Question 34

What pump is used to carry out static checks?

Answer 34

Electric feathering pump

Question 35

What are some static checks?

Answer 35

- Flight Fine Pitch Stop (FFPS) - Auto-coarsening - Manual Feather - Autofeather - Unfeather

Question 36

When are static checks usually carried out?

Answer 36

Prior to an engine ground run

Question 37

What is the benefit to static checks?

Answer 37

The engine does not need to be run

Question 38

Piston engines were further classified as what?

Answer 38

Normally aspirated and supercharged

Question 39

The air pressure in the engine air induction manifold is known as what?

Answer 39

Manifold Air Pressure

Question 40

How is the reference RPM checked?

Answer 40

Setting the propeller to a fine pitch, advancing the throttle until the manifold pressure reads zero boost

Question 41

What is the reference RPM?

Answer 41

The RPM when it reaches 0 boost

Question 42

What way should the aircraft face during an engine test?

Answer 42

Into the wind

Question 43

Below what temperature must the anti-ice be on?

Answer 43

10℃

Question 44

Turboprop engine power is measured in what?

Answer 44

Shaft horsepower

Question 45

To determine that the engine is operating correctly then the engine exhaust gas temperature (EGT) and fuel flow (FF) must be monitored against the referenced what? (Piston)

Answer 45

Torque and RPM

Question 46

What two pieces of formation are required to correct a propeller dynamic imbalance?

Answer 46

Vibration level and phase angle

Question 47

What is the purpose of the steel wire mesh?

Answer 47

Inhibit blade tip erosion

Question 48

When airspeed increases what happens to the brake moment?

Answer 48

Brake moment decreases

Question 49

What does ACF stand for?

Answer 49

Aerodynamic Correction Factor

Question 50

Where do fatigue failures occur?

Answer 50

Few inches from tip