27 Gas Turbines Bleed Air – LMS

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📄 Notes ⚡ Cheat Sheet

Q1. The heat for the anti-icing system of a turbofan engine intake is provided by:

bleed air from the HP compressor.

bleed air from the LP compressor.

a dedicated generator on the gearbox of that engine.

the electrical system of the aircraft.

Q2. Ice formation on turbofan engine intakes is usually:

removed by using electrical heating.

prevented by using turbine bleed air.

prevented by using compressor bleed air.

removed by using pneumatic boots.

Q3. The selection of bleed air to “ON” will cause:

an increase in exhaust temperature, gas generator speed and power

a reduction of torque and gas generator RPM with an increase of exhaust temperature

a decrease in gas generator RPM with no change in power or exhaust temperatures

a decrease in power and an increase in exhaust temperature

Q4. Bleeding air from the HP compressor of a turbofan, whilst maintaining thrust, increases:

EGT and fuel flow.

N2 and fuel flow.

HP compressor discharge pressure and N2.

EGT and N1.

Q5. A gas turbine engine is run at ground idle for a period of time prior to shutdown to:

allow the engine oil to cool.

prevent seizure of the engine bearings.

prevent vapour lock in the fuel control and/or fuel lines.

prevent seizure of the rotor blades in their seals.

Q6. The take off of a jet aeroplane may be performed with “reduced thrust” in order to:

reduce take-off noise.

reduce maintenance costs.

reduce the risk of engine failure during take-off.

save fuel.

Q7. The purpose of gas turbine engine trending is:

to assess engine condition using non-destructive inspection.

to enhance maintenance planning and detect anomalies.

to collect metal particles from the oil system.

to obtain a timely indication when an engine requires to be shut down due to problems.

Q8. On landing and prior to shut down, a gas turbine engine should be run at “GROUND IDLE” for a short period. This allows:

the engine to be compressor washed

the core temperature to diminish

the turbine blade temperature to reduce only

cool oil flushing of bearings, particularly those in the turbines

Q9. Which of the following statements is UNTRUE?

a) Bleed air may be supplied by an APU

d) Use of engine bleed air reduces thrust

b) Bleed air may be taken from the HP compressor of a gas turbine engine

c) Engine bleed air is considered to be high presssure

Q10. One of the purposes of the bleed valves fitted to axial flow compressors is to:

d) enable an external air supply to spin up the compressor for engine starting

b) control the acceleration time of the engine

a) spill compressor air should the engine overspeed thus controlling the speed

c) reduce the tendency to compressor stall

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