15.17 - Turboshaft Engines.

Question 1

What is a turbo shaft engines output measured in

Answer 1

Shaft horsepower instead of thrust.

Question 2

What two major parts are turbo shaft engines made up off

Answer 2

Gas generator and the power section.

Question 3

What situations are turboshaft engines used in

Answer 3

Scenarios where sustained high-power output is needed.

Question 4

Why are drive systems fitted to turboshaft engines.

Answer 4

To transfer the power produced in the engine to the components it use drive.
For example in helicoptors this is the main rotor gear box. While for APUs it can be the electrical generator.

Question 5

What is used to allow two engines to power one drive shaft.

Answer 5

A common gear box with a freewheeling unit to automatically disconnect the slower engine.
The freewheel unit is normally in the form of a sprag clutch.

Question 6

Why are turboshaft couplings used.

Answer 6

To ensure that adequate movement of the transmission can take place.
Provide the driveshaft with flexibility for the deflections caused by the transmissions movements.
Flexibility is provided by stainless steel discs bolted to the shaft.
Require inspection at regular intervals.
Fail safe and show gradual and visible deterioration.

Question 7

Controlling engine for medium to large helicopters

Answer 7

Uses a FADEC.
OFF - sends a signal for engine shut down or to abort a starting sequence.

IDLE - engine runs at idle speed.

FLIGHT - engine runs at full speed, power requirements are managed by fadec increasing fuel flow.