Propellers

Question 1

Propellers change _____ energy into _______ energy

Answer 1

-Chemical
-Kinetic

Question 2

Thrust produced by a propeller depends on what 5 things?

Answer 2

-Shape of the blade
-Area of the blade
-Angle of attack
-Density of the air
-Speed of the airfoil through the air

Question 3

The speed of the blade through the air changes along the _______ of the blade

Answer 3

Length

Question 4

The angle of attack changes along the _______ of the blade for maximum efficiency

Answer 4

Length

Question 5

Pitch angle is the angle between?

Answer 5

The chord line of the blade and the plane of rotation.

Question 6

Angle of attack is the angle between?

Answer 6

The chord line and relative wind

Question 7

Geometric pitch

Answer 7

Path the propeller would take if acting as a screw through a solid

Question 8

Effective pitch

Answer 8

Is the actual path through the air

Question 9

Slip

Answer 9

Is the difference between geometric and effective pitch

Question 10

The efficiency of a propeller is a ratio between?

Answer 10

Thrust horsepower and Torque Horsepower

Question 11

Thrust horsepower

Answer 11

How much of the engine is actually pushing air aftward

Question 12

Torque horsepower

Answer 12

How much engine power is needed to run the propeller

Question 13

Engine power translated into thrust depends on?

Answer 13

-Engine speed
-Aircraft air speed
-Blade pitch

Question 14

5 forces acting on a propellers?

Answer 14

-Centrifugal
-Thrust bending
-Torque bending
-Aerodynamic twisting
-Centrifugal twisting

Question 15

Thrust bending force?

Answer 15

Pull the blades forward near the tip

Question 16

P-factor has 2 parts

Answer 16

-Asymmetrical thrust
-Slipstream yaw effect

Question 17

What are the different ways to mount a propeller on a crankshaft?

Answer 17

-Flanged crankshaft
-Splinned shaft
-Tapered shaft

Question 18

What are the two factors that make the AOA of a prop blade vary?

Answer 18

-Forward speed of the aircraft
-RPM of the engine

Question 19

Which force acting on a propeller puts the greatest stress on the propeller?

Answer 19

Centrifugal Force

Question 20

Explain the procedure of ground adjustable propellers being adjusted.

Answer 20

When the aircraft is on the ground an AMT adjusts the desired blade angle of each prop blade using a blade paddle and propeller protractor.

Question 21

What is the purpose of a constant-speed propeller?

Answer 21

Blade pitch of the propeller blades change the load of the engine by making the propeller easier or harder to turn, this keeps the engine speed constant.

Question 22

What is a counterweight propeller?

Answer 22

Has weight attached to blade roots to help move blades into high pitch and oil pressure moves blades against the force to counterweights into low pitch.

Question 23

What are non-counterweight propellers?

Answer 23

Uses oil pressure and aerodynamic twisting force to increase pitch, and centrifugal twisting force and internal spring force to decrease pitch.

Question 24

Some constant speed propellers are reversible, explain how this works?

Answer 24

Low pitch stops can be released so the blades can be moved from low pitch to a negative blade angle allowing propeller to produce thrust in the reverse direction.

Question 25

On turboprop engines what are the two standard operating modes and when are they used?

Answer 25

-Alpha:flight mode -Beta: ground mode

Question 26

What are the 3 common fixed pitch propeller designs and there characteristics?

Answer 26

-Climb prop: Lower pitch angle transferring ore engine power at takeoff but slower cruise speed -Cruise prop: Max efficiency at altitude, but longer takeoff. -Standard: Split difference

Question 27

What does the pilot use the propeller control lever and throttle for?

Answer 27

-Prop control lever to set desired engine RPM -Throttle to set engine power(MAP)

Question 28

Name two controls and two instruments pilots use to monitor engine performance.

Answer 28

Controls: Throttle, condition lever, prop control Instruments: Tach, torquemeter, fuel flow, EGT

Question 29

Name 2 types of material used for composite blades.

Answer 29

-Carbon fiber -Graphite -Fiberglass -Kevlar

Question 30

What type of work can AMT's perform on propellers?

Answer 30

-Remove and install -Inspection -Service/maintain -Minor repair -Tracking and balancing

Question 31

What can happen if unequal amounts of grease are added to different prop blades?

Answer 31

Unequal amounts of grease can cause prop imbalance

Question 32

What information about the prop can be found in the TCDS?

Answer 32

-Blade length limits -Approved prop/engine combinations -Approved governors -Model number explanation -TBO reference

Question 33

Name the tools for adjusting blade pitch?

Answer 33

-Blade paddle -Propeller protractor

Question 34

Why is it important to remove damage to propellers?

Answer 34

Forces acting on propellers can cause minor damage to worsen. Propeller damage can cause severe vibrations, engine shutdown, engine/aircraft damage, accidents

Question 35

Name some considerations when applying grease to a propeller?

Answer 35

-Use of the correct grease -Proper application of the grease -The proper amount of grease applied

Question 36

Name the types of constant-speed prop?

Answer 36

-Counterweight -Non-counterweight -Hydromatic

Question 37

Explain constant speed?

Answer 37

Governor controlled, the prop changes blade pitch automatically keeping engine RPM constant

Question 38

What is a critical engine?

Answer 38

1 of 2 engines on a multi-engine aircraft, the engine on the side of the aircraft that is producing less thrust is labeled as the critical engine

Question 39

What are the 2 instruments used on recip engines to monitor engine/prop performance?

Answer 39

-Tach -Manifold pressure gauge

Question 40

What is asymmetrical thrust?

Answer 40

At take off/climb, down going blade has a lager AOA than up going blade creating more thrust on that side of the prop