PC-21 Propeller System

Question 1

What propeller is the PC-21 fitted with? What direction does it rotate?

Answer 1

• Composite, five blade, Hartzell constant speed feathering propeller.
• Clockwise

Question 2

What is the purpose of the propeller?

Answer 2

Convert engine rotation to thrust to propel the aircraft.

Question 3

What does the engine turn the propeller through?

Answer 3

Reduction gearbox and propeller shaft.

Question 4

What prop speeds produce high efficiency?

Answer 4

Close to the speed of sound.

Question 5

What design feature is included to reduce the propeller noise and improve efficiency?

Answer 5

Sweeping the blades back.

Question 6

What are the advantages of a constant speed (RPM) prop?

Answer 6

1. Allows prop to operate a maximum efficiency

2. Allows the engine RPM to remain within the narrow RPM range ideal for turboprops.

Question 7

What are some advantages of composite blades?

Answer 7

1. Longer service life

2. Substantial weight reduction

Question 8

What does increasing the number of blades allow for?

Answer 8

1. Noise reduction
2. Less vibration
3. Smaller diameter propeller that is less vulnerable to FOD.

Question 9

What are the main components and subsystems of the propeller system?

Answer 9

1. Propeller assembly
2. Propeller control system
3. Propeller de-ice system
4. Propeller related cockpit controls.

Question 10

What are the three propeller sub assembly components?

Answer 10

1. Blades
2. Spinner
3. Hub Assembly

Question 11

What does each blade have?

Answer 11

1. Counterweight that continually attempts to turn the blade back towards the coarse pitch and feathered position, due to props rotational centrifugal force
2. A titanium erosion strip that protects the leading edge surfaces of the blade from the effects of erosion and provides an earth path in case of a lighting strike
3. De-Icing strip that prevents build-up of ice on the blades.

Question 12

What is the spinner and what is it made of?

Answer 12

1. Protects the propeller hub and gives it an aerodynamic shape.
2. Made from graphite composite material.

Question 13

What is the hub assembly and what is it made of?

Answer 13

Aluminum hub assembly is attached to the prop shaft and holds each propeller in place on a thrust bearing, which allows the blade to change its pitch angle.

Question 14

What is the main purpose of the propeller control system?

Answer 14

To automatically change the propeller blade angle to maintain propeller speed at 100% RPM throughout the various power settings

Question 15

What are the key components of the prop control system?

Answer 15

• Power Management Unit (PMU)
• Propeller Interface Unit (PIU)
• Power Control Lever (PCL)

Question 16

What are the key components of the propeller de-ice system?

Answer 16

1. De-ice strip, with built-in heater element, on each propeller blade
2. Prop de-ice controller with two control OAT sensors
3. Prop push button on de-ice panel.

Question 17

What prop controls are related to the prop system?

Answer 17

1. PCL

2. PROP push button.

Question 18

How does the PCL indirectly control the pitch angle of the prop blades?

Answer 18

Through interaction with engine PMU and the PIU.

Question 19

What external systems does the propeller system integrate with?

Answer 19

1. Power plant
2. Alerting system
3. Health and Usage Monitoring System
4. Landing gear WOW and PCL sensors.

Question 20

How is the prop heater elements powered?

Answer 20

From GEN 2 BUS

Question 21

Where is the PIU on the engine and how is it controlled?

Answer 21

1. On top of the reduction gearbox

2. Controlled by the PMU

Question 22

What type of component is the PIU?

Answer 22

Electro-hydraulic-mechanical component

Question 23

How do the primary governor and the mechanical overspeed governor in the PIU work?

Answer 23

Use controlled oil pressure from reduction gearbox to then control the propeller blade angle and consequently, the propeller rotational speed.

Question 24

What does propeller do when PCL is in FUEL OFF position?

Answer 24

Electrically commanded to feather to provide least amount of drag in case of an engine shut-down in the air.

Question 25

What occurs during engine start when the PCL is moved to the IDLE position?

Answer 25

The propeller is electrically commanded to unfeather and as engine oil pressure increases, the PIU will rotate the propeller blades towards the fine pitch position.

Question 26

What will occur with a loss of oil pressure or engine failure?

Answer 26

Blades will automatically feather.

Question 27

Under what conditions does the prop de-ice controller not work?

Answer 27

- OAT > 10 C - Engine oil pressure is < 40 psi - Prop speed is < 630 RPM

Question 28

Which displays show prop related info?

Answer 28

1. EMD 2. MFD ENG 3. DWP 4. DE-ICE panel

Question 29

When is the prop RPM indication show on the MFD ENG page ?

Answer 29

When prop speed increases > 320 RPM.

Question 30

When is the prop speed displayed on the EMD?

Answer 30

When it is approaching a limit or is going out of limits.

Question 31

What occurs when Prop de-ice is turned on?

Answer 31

Green PROP will display on DWP | Will display ON on the de-ice panel.

Question 32

What should be checked on the propeller during the preflight?

Answer 32

1. Ensure that there is no grease or oil leaking from the spinner or running down the propeller blades 2. Check the blades for scratches, nicks, cracks or signs of debonding. If any are found ask the groundcrew to determine whether the prop is still airworthy. 3. Ensure de-ice boots are securely attached to the blades. 4. Check prop blades for evidence of lightning strikes. 5. Rotate the propeller and check that is moves easily without grinding or scraping noises. 6. Ensure that the prop is firmly mounted.

Question 33

Is the PC-21 cleared for flight into know icing conditions?

Answer 33

No

Question 34

What should be done if icing conditions arise?

Answer 34

1. Activate de-ice system to prevent ice formation | 2. Take action to leave the area immediately.

Question 35

What is the common cause if aircraft power has to be increased to maintain speed or vibrations occurs?

Answer 35

Icing

Question 36

What should be done to the prop when flying is complete?

Answer 36

Ensure that the prop restraints are replaced to prevent the propeller from continuously wind-milling without oil supply to the reduction gearbox bearings.

Question 37

When surface wind is from behind, what RPM should the prop be limited to?

Answer 37

1600 RPM.

Question 38

What actions should be taken in Manual mode to keep prop within limits?

Answer 38

1. Avoid rapid power changes and move the PCL carefully | 2. Ensure that the prop remains above 1900 RPM is the NG is > 90%

Question 39

What may occur in the event of a compressor stall or surge with the propeller?

Answer 39

The propeller RPM may also surge.

Question 40

When will a red PROP SPEED warning displayed in the alert area on the MFD/ EMD area?

Answer 40

When the prop RPM > 2200 RPM.

Question 41

When is the amber PROP SPEED caution displayed?

Answer 41

1. IF prop speed is > 2080 RPM for > 3s. | 2. If propeller speed < 1900 RPM for > 3 s while NG > 90%.

Question 42

When will amber ICE PROP caution be displayed in the alert area on the MFD and an amber ICE caption on the DWP?

Answer 42

1. A malfunction is detected in the propeller de-ice system | 2. When the propeller de-icing is selected ON, when the OAT > 10 C

Question 43

What warning is shown when metal particles are detected in the propeller reduction gearbox?

Answer 43

Amber CHIP PROP caution is shown in the MFD alert area and an amber CHIP caption is shown on the DWP.

Question 44

What will show if the metal particles sense function for the prop reduction gearbox is not available?

Answer 44

A grey CHIP PROP ALRT advisory is shown in the MFD alert area.

Question 45

What will occur when the Propeller Interface Unit increases the oil pressure to the propeller assembly?

Answer 45

It will make the propeller blade angle smaller (fine pitch)