Propeller

Question 1

Describe the Propeller

Answer 1

Two mt-Propeller hydraulically regulated 3-bladed constant speed feathering

Question 2

What is the propeller made of and why?

Answer 2

Wood composite with fibre-reinforced plastic coating and stainless steel cladding (LE).
because it has a low weight whilst minimising vibration and reducing rotational inertia.

Question 3

What system controls the Propeller pitch?

Answer 3

ECU - gearbox oil pumped into propeller hub (changes blade pitch angle)

Question 4

How is the Oil pressure regulated?

Answer 4

Master Switch on.

Regulated by electrically operated governor valve controlled by the ECU at the nitrogen oil type pressure accumulator.

Question 5

What happens to pitch and RPM with oil pressure?

Answer 5

Increase Oil Pressure

• decreases pitch
• higher RPM

Question 6

Pitch change steps.

Answer 6

Engine master ON -> valve open -> engine running -> accumulator filled with oil

Question 7

What does the accumulator do?

Answer 7

Makes sure enough oil pressure is available even is oil feed by the gearbox oil pump is decreasing (due to negative acceleration)

Question 8

Why is the blade pitch adjusted?

Answer 8

So the required RPM is obtained depending on power setting set

Question 9

Process of feathering

Answer 9

Shut down engine (Master switch OFF) -> opens electric governor valve -> all oil flow back from hub -> blades in feathered pitch position
AT same time the electric valve at the pressure accumulator closes and oil pressure is restored in accumulator.

Question 10

Can you feather the engine at any RPM?

Answer 10

No needs to be at leat 1300RPM

Question 11

Key propeller pitch angles?

Answer 11

12 - Low pitch
15 - Start lock postion
81 - Feathered

Question 12

Key propeller RPMs?

Answer 12

2300 - max TO and continues power

2500 - max overspeed 20secs