Aircraft Systems

Question 1

Propeller

Answer 1

• Converts torque of crankshaft into thrust
• Moves large mass of air backwards at slow speed
• Produces lift and drag where is lift is thrust and drag is torque

Question 2

Propeller Pitch

Answer 2

• Distance in feet a prop travels forward in one revolution
• Theoretical/Geometric Pitch is how far the prop would travel if it were 100% efficient
• Practical/Effective Pitch is the actual distance the prop travels
• Prop slip is the difference between theoretical and practical pitch

Question 3

Coarse Pitch

Answer 3

• Low RPM
• Large angle, big bite of air
• Moves at slower speed
• Travels greater distance
• Used during cruise

Question 4

Fine Pitch

Answer 4

• High RPM
• Small angle, small bite of air
• Moves at higher speed speed
• Travels smaller distance
• Used during takeoff/climb

Question 5

Constant Speed Propellers

Answer 5

• Automatically adjust blade angle to maintain given RPM
• Uses flyweights which sense engine speed
• pilot valve which change the blade angle

Question 6

Constant Speed Prop Overspeed

Answer 6

• Occurs when conditions try to increase the prop RPM by decreasing the load
• Nose down attitude
• Engine speed increases
• Flyweights spin faster and tilt outwards, pilot valve moves prop into coarser pitch, decreasing RPM back to original RPM

Question 7

Constant Speed Prop Underspeed

Answer 7

• Occurs when conditions try to decrease prop RPM by increasing the load
• Nose up attitude
• Engine speed decreases
• Flyweights spin slower and tilt inwards, pilot valve moves prop into finer pitch, increasing RPM back to original RPM

Question 8

Prop Reversing

Answer 8

• Used to slow aircraft on landing
• Moves blade past fine pitch so it produces negative thrust

Question 9

Cowl Flaps

Answer 9

• Used for cooling engine
• Should be open for climbs and closed for descents
• usually closed during cruise

Question 10

Generators

Answer 10

• Produce current proportional to engine RPM
• Low RPM can mean insufficient output to run all systems
• Can re-charge a dead battery

Question 11

Alternator

Answer 11

Produces sufficient current at low engine RPM

Question 12

Voltage Regulator

Answer 12

• Prevents the Generator or Alternator from over-loading the system
• Prevents the battery from becoming overcharged

Question 13

Bus Bar

Answer 13

• Receives current from generator or alternator and battery
• Distributes it through Circuit Breakers to the various electrical systems

Question 14

Hot Buses

Answer 14

• Systems that are active whether or not the master switch is on or off
• usually lights or essential systems

Question 15

Combustion Heater

Answer 15

• Commonly used on multi-engine aircraft to provide cabin heatUses aircraft’s fuel supply
• Over heat switch prevents system from over heating on the ground