15.17 Turboshaft engines

Question 1

What is the main output of a turboshaft engine?

Answer 1

Shaft power measured in Shaft Horsepower (SHP).

Question 2

What are the two main sections of a turboshaft engine?

Answer 2

Gas generator and power section.

Question 3

What does a freewheel unit (sprag clutch) do in a twin-engine turboshaft setup?

Answer 3

Prevents one engine from driving the other.

Question 4

Why is reduction gearing needed in turboshaft engines?

Answer 4

Flexible stainless-steel disc couplings.

Question 5

Why must flexible couplings be inspected regularly?

Answer 5

They undergo fatigue from repeated movement and are designed to fail visibly

Question 6

What are the three FADEC engine control positions on a helicopter?

Answer 6

A: OFF, IDLE, FLIGHT.

Question 7

How does a sprag cluctch prevent one engine from driving the other?

Answer 7

It prevents one engine from driving the other by allowing rotation in only one direction—if one engine slows down or fails, the clutch disengages it, allowing the working engine to continue driving the gearbox without back-driving the failed engine.