15.17 - Turbo-shaft Engines Flashcards Preview

Module 15 - Gas Turbine Engines > 15.17 - Turbo-shaft Engines > Flashcards

Flashcards in 15.17 - Turbo-shaft Engines Deck (12)
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1
Q

What is the MRG?

A

The main reduction gearbox

2
Q

What type of gears are usually used in the MRG?

A

Epicyclic gears

3
Q

What is the purpose of the freewheel unit on a helicopter?

A

Prevents the rotor from driving the engine. They are always automatic units.

4
Q

What is the most common used freewheel unit in helicopters?

A

The sprag clutch

5
Q

How does a sprag clutch work?

A

It only allows rotation in one direction. The sprags are spring loaded and placed slightly on an angle

6
Q

What is the Thomas coupling?

A

The most common type of disc coupling. (Connecting the power unit to the main rotor gearbox)
It is a ‘flexible’ coupling that allows for vibration and slight misalignment.

7
Q

Where would you find the K-flex coupling?

A

Between the freewheeling unit and the gearbox. It has 3 rectangular plates which allow for angular misalignment and length changes. It also has a fail safe feature

8
Q

What happens to the rotor angle of attack when the side collective stick is raised?

A

The angle of attack increases

9
Q

What is the purpose of the free turbine governor?

A

It acts as a constant speed unit, giving constant output RPM throughout all flight conditions. It uses a flyweight-controlled governor.

10
Q

What is the purpose of the beeper system?

A

It allows the pilot to set a new datum for the free turbine governor. It lets the pilot select extra power due to the free turbine not fully compensating to the load changes.

11
Q

What is a curvic coupling?

A

It accurately aligns the driving and driven shafts

12
Q

What two types of torquemeters are used on turboshaft engines?

A

Electro-mechanical and oil