Propellers

Question 1

What is the construction material of the mt-Propeller?

Answer 1

Wood-composite construction with a fiber-reinforced plastic coating

The mt-Propeller features a combination of wood and advanced plastic materials for enhanced durability and performance.

Question 2

What protects the inner edge of the mt-Propeller blades?

Answer 2

A rubber strip

This rubber strip is designed to provide additional protection against wear and damage.

Question 3

What protects the outer edges of the mt-Propeller blades?

Answer 3

A stainless steel clad edge

The stainless steel edge adds strength and resistance to environmental factors.

Question 4

What type of regulation does the mt-Propeller use?

Answer 4

Hydraulically regulated, constant speed, full-feathering

This mechanism allows for efficient and responsive control of the propeller’s pitch.

Question 5

How are the blades moved to a coarse pitch?

Answer 5

By counterweights and spring tension

This system utilizes mechanical forces to adjust the blade pitch for optimal performance.

Question 6

How are the blades moved to a fine pitch?

Answer 6

By gearbox oil pressure controlled by the CSU

The Constant Speed Unit (CSU) plays a critical role in adjusting the blade pitch based on engine performance.

Question 7

What should be checked during a preflight propeller inspection?

Answer 7

Each blade, front and back, leading and trailing edges

Question 8

What type of surface damage is common on propeller blades?

Answer 8

Surface nicks, especially on the rear face

Question 9

What is the acceptable condition for minor surface nicks on propeller blades?

Answer 9

Minor surface nicks are acceptable

Question 10

What maintenance is required if nicks or de-lamination exposes underlying wood fibers?

Answer 10

Maintenance is required

Question 11

What condition indicates that maintenance is required in relation to the propeller hub?

Answer 11

If grease or oil appears to be leaking from the propeller hub

Question 12

What does the ECU command the CSU to do?

Answer 12

Set optimum propeller RPM for percentage power commanded by pilot

Question 13

How does the CSU control the propeller’s blade pitch?

Answer 13

By controlling the amount of gearbox oil in the propeller hub

Question 14

What effect does increased oil volume in the hub have on the propeller?

Answer 14

Results in a finer blade pitch (higher RPM)

Question 15

What is the oil pressure boosted by the Combi Pump?

Answer 15

Approximately 290 PSI

Question 16

What is the maximum continuous power RPM?

Answer 16

2300 RPM

Question 17

What is the overspeed limit and duration?

Answer 17

2500 RPM for up to 20 seconds

Question 18

What type of governor does the DA42NG use?

Answer 18

mt P-877-16 electric governor

Question 19

What is the maximum takeoff power RPM for the DA42NG?

Answer 19

2300 RPM (5 minutes total per flight)

Question 20

What is the maximum continuous power RPM for the DA42NG?

Answer 20

2100 RPM

Question 21

What should be done before turning off the Engine Master?

Answer 21

Power lever should be at idle

Question 22

What happens to the propeller when the engine stops with RPM above 1300 RPM?

Answer 22

The propeller will feather

Question 23

What prevents the propeller from feathering below 1300 RPM?

Answer 23

Coarse stop pins

Question 24

What do the ECUs do as power is reduced while airborne?

Answer 24

Reduce propeller RPM until reaching 25%

Question 25

What action do the ECUs take below 25% power?

Answer 25

Increase propeller RPM to ensure feathering if the engine is shutdown

Question 26

True or False: Increased propeller RPM is associated with power settings below 25%.

Answer 26

True

Question 27

What may cause propeller blades to move to the highest RPM setting?

Answer 27

A malfunction ## Footnote This can lead to a condition known as propeller over-speed.

Question 28

What should be done if over-speed occurs in a propeller?

Answer 28

Reduce power on the affected engine and terminate the flight as soon as practicable ## Footnote This helps control the RPM.

Question 29

What action should be considered if unable to maintain 2300 RPM or less?

Answer 29

Consider shutting down the affected engine ## Footnote This is crucial for safety if power reduction fails.

Question 30

What power setting should be used after takeoff in a DA42NG?

Answer 30

Reduce power levers to 92% ## Footnote This should be done after reaching a safe altitude.

Question 31

What is the recommended engine power setting during climbs above 14,000 feet MSL?

Answer 31

Reduce power settings below 92% ## Footnote This prevents RPM from entering the yellow range.

Question 32

What is the purpose of unfeathering accumulators?

Answer 32

Enable restarting an engine while airborne ## Footnote They store pressurized gearbox oil to assist in propeller movement.

Question 33

What do unfeathering accumulators store?

Answer 33

Pressurized gearbox oil in a nitrogen-charged metal cylinder ## Footnote This allows for the movement of the propeller out of the feathered position.

Question 34

What happens when the Engine Master switch is turned ON?

Answer 34

Accumulator releases gearbox oil to move the propeller out of the feathered position ## Footnote This is essential for engine restart procedures.

Question 35

At what speeds is the starter used to start the engine?

Answer 35

Below 90 KIAS ## Footnote This is important for safe engine start procedures.

Question 36

True or False: Engaging the starter while the propeller is wind-milling is safe.

Answer 36

False ## Footnote It may result in an L/R ECU A/B FAILURE CAS message.

Question 37

What may happen if the starter is disengaged below 500 RPM?

Answer 37

It may cause damage to the gearbox ## Footnote This highlights the importance of proper RPM management during engine operations.

Question 38

What is the maximum time allowed to restart an engine after shutting down for training purposes while airborne?

Answer 38

Within two minutes ## Footnote Restart may not succeed if the engine is not restarted within this timeframe.

Question 39

What are the two types of air start procedures defined for the DA42NG?

Answer 39

* Windmilling propeller at 120 to 140 KIAS * Engine starter at 85 to 100 KIAS

Question 40

What does FAA Airworthiness Directive 2018-18-02 limit regarding windmilling restart?

Answer 40

Use for emergencies only ## Footnote This is to prevent failure of engine timing chain, loss of engine thrust control, and reduced control of the airplane.

Question 41

What may happen if the starter is engaged while the propeller is wind-milling?

Answer 41

An L/R ECU A/B FAILURE CAS message may occur ## Footnote This is a warning to avoid engaging the starter under such conditions.