POWERPLANT SAJO 2

A waste gate controls the output of a turbocharger by varying the amount of exhaust gasses passing through the turbocharger's (1) _____. A fully (2)____ waste gate will achieve the maximum turbocharger RPM.

• (1) turbine; (2) open

• (1) compressor; (2) open

• (1) compressor; (2) open

• (1) turbine; (2) closed

When changing power on piston engines equipped with a constant speed propeller, engine overboost is avoided by...

• increasing the manifold pressure before increasing the RPM.

• increasing the manifold pressure before adjusting the fuel flow.

• reducing the RPM before reducing the manifold pressure.

• increasing the RPM before increasing the manifold pressure.

Which of these statements about compressor stall in a gas turbine engine are correct or incorrect?

I. A compressor stall is most likely to occur in a compressor designed for a high pressure ratio operating at low RPM
II. A compressor stall is most likely to occur when the air flow stagnates in the front stages of the compressor

• I is incorrect, II is correct.

• I is correct, Il is incorrect.

• I is incorrect, II is incorrect.

• I is correct, II is correct.

In a gas turbine combustion chamber...

• secondary air is required for cooling of the inner casing.

• the gas temperature is highest at the chamber outlet.

• the gas pressure increases in an axial (downstream) direction.

• the axial velocity of the gas stream is greatest behind the swirl vanes.

In a gas turbine engine, compressor surge during engine acceleration is prevented by...

• variable setting type nozzle guide vanes.

• Outlet guide vanes.

• controlling the fuel flow.

• anti-ice bleed valves.

A turbofan engine with an inlet air mass flow of 300 kg/s and a HP compressor mass flow of 50 kg/s has a bypass ratio of...

• 5

• 1.7

• 6

• 4

A twin engine turbofan aircraft uses dual channel FADEC. Which of the following statements correctly describes the operation of each channel?

• Each channel processes different data; one channel for inputs and the other for outputs.

• One channel serves the ECU and the other serves the hydro-mechanical control unit.

• Each channel controls the engine on that side, and data is sent to the other channel.

• One channel is in command, and the other channel can take over in case of fault or failure.

The function of the swirl vanes round the fuel nozzles in a gas turbine engine is to:

1. increase air pressure at the fuel nozzles

2. reduce the average axial flow speed in order to stabilise the flame front

3. generate a swirl of incoming air to enhance mixing of the fuel with air

The combination that regroups all of the correct statements is...

• 1,2

• 2,3

• 1,2,3

• 2