Turbo Props/Anti Icing

Question 1

What is the alpha range in pitch control?

Answer 1

In a turboprop engine, it is the range of power lever positions between flight idle and maximum power

Question 2

What is the beta range in pitch control?

Answer 2

Flight idle through ground idle to reverse pitch,

Question 3

What is reverse pitch?

Answer 3

Propgoes into a negative blade angle to force air forward.

Question 4

What is the feather position?

Answer 4

The blade is parallel to airflow to reduce drag on an engine which is shutdown

Question 5

What are some benefits and hazards of reverse pitch?

Answer 5

Assists with breaking
Hazardous to use airborne (re-ingestion of exhaust gases
FOD ingestion
Monitor gauges risk of over-torque/ over temp

Question 6

Explain the purpose of the pitch control unit when the pilot inputs an increase of power?

Answer 6

PCU holds the RPM within a few hundred RPM at all times, so with the increase of power, the blade angle is coarsened by the PCU at the same time the fuel enters the engine therefore more thrust is produced but with similar RPM

Question 7

Why is there a requirement for anti-icing on a propeller?

Answer 7

Because if there is ice formation on a propeller when the aircraft is in flight it will alter the aerofoil shape of the prop and decrease thrust and cause vibrations.

Question 8

What is the fluid anti-icing system generally used on a propeller

Answer 8

isopropyl alcohol (fluid pumped from a tank to the prop hub where it is sprayed onto the leading edges)
This lead to corrosion

Question 9

What is the modern method of de-icing?

Answer 9

Electrical heaters are housed in rubber boots placed on the leading edge of the propeller cuffs of the blade.
They have embedded heat wires attached to the prop root driven by an engine-driven AC generator.

Question 10

How is ice warning detected?

Answer 10

Through warning lights in the cockpit, an ice warning detector may require arming.

Question 11

What are some effects of icing?

Answer 11

Restricts airflow
Reduces performance
Possible Malfunction
Possible damage

Question 12

What are the requirements of an anti-icing system?

Answer 12

Must be effective
Reliable
Easy to maintain
No excessive weight
No serious loss to engine performance

Question 13

Where is the hot air usually taken from in an engine for anti-icing?

Answer 13

The high-pressure compressor