DGCA Gas Turbine 7. Lubrication

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Q1. A centrifugal breather is used on a gas turbine engine:

to circulate the oil smoothly.

to minimize oil loss.

to emulsify the oil and air mixture for greater viscosity.

to allow oxidization of the oil.

Correct answer is – to minimize oil loss.

Q2. A high oil temperature would indicate that:

the oil pressure was high.

the exhaust gas temperature (EGT) was high.

the oil filter was blocked.

the air intake of the oil cooler was blocked.

Correct answer is – the air intake of the oil cooler was blocked.

Q3. Oil seals are pressurized:

to ensure oil is forced into the bearings.

to ensure minimum oil loss.

to ensure that the oil is prevented from leaving the bearing housing.

to minimize heat loss in the bearing housing.

Correct answer is – to ensure minimum oil loss.

Q4. In the event that damage occurs to the matrix of the fuel-cooled oil cooler:

a pressure-maintaining valve ensures that the oil pressure is always higher than the fuel pressure.

the fuel pressure is always kept higher than the oil pressure to ensure that the fuel will leak into the oil system.

a differential pressure switch will illuminate a light in the cockpit.

the oil bypass valve will prevent a complete loss of oil pressure.

Correct answer is – a pressure-maintaining valve ensures that the oil pressure is always higher than the fuel pressure.

Q5. The bearing chambers of a gas turbine engine are vented:

via the auxiliary gearbox drive.

via the centrifugal breather.

via the air seals, into the gas stream.

to prevent oil loss.

Correct answer is – via the centrifugal breather.

Q6. The main bearings in an axial flow gas turbine engine are normally pressurized by:

compressor bypass air.

air at intake pressure.

air from an intermediate stage of the compressor.

gas from the second stage turbine section.

Correct answer is – air from an intermediate stage of the compressor.

Q7. Magnetic Chip Detectors are fitted in the engine:

to facilitate early detection of cracks in the compressor blades.

to facilitate early warning of cracks in the turbine blades.

to provide a warning of impending failure in the engine bearings.

to prevent a build up of starch in the scavenge oil filter.

Correct answer is – to provide a warning of impending failure in the engine bearings.

Q8. An inter-stage air seal is used where:

engine sections are operating at different pressures.

engine sections are subjected to pressures of the same value.

it is more convenient.

it is difficult to obtain access during routine servicing.

Correct answer is – engine sections are operating at different pressures.

Q9. An Internal Engine Overheat warning would necessitate:

the oil temperature to be closely monitored.

the EGT to be closely monitored.

the engine power to be reduced to idle.

the engine to be shut down.

Correct answer is – the engine to be shut down.

Q10. If engine run down time is short, coupled with high oil consumption, the most probable cause is:

compressor blade rub.

incorrect relief valve setting.

excessive sealing air pressure.

bearing chamber labryinth seal rubbing.

Correct answer is – bearing chamber labryinth seal rubbing.

Q11. Gas turbines use for lubrication:

mineral oil with additives (compound).

mineral oil straight.

multi-grade 20/50.

synthetic oil.

Correct answer is – synthetic oil.

Q12. For a pressure relief lubricating system, select the correct statement:

the flow and pressure change with engine speed.

the pressure relief valve is fitted in series with the pump.

the relief valve opens when pressure has reached the required pressure.

Any excess flow is returned by a dedicated line to the base of the engine for scavenging.

Correct answer is – the relief valve opens when pressure has reached the required pressure.

Q13. If the engine oil pump ceases to function the engine:

will continue to operate at a lower rpm because the engine will be able to suck the oil from the reservoir and be sufficiently lubricated.

should be shut down.

will be unaffected because the scavenge pumps have a larger operating capacity than the pressure pumps and will ensure the engine is lubricated sufficiently.

should be monitored for a period of time to record oil temperature.

Correct answer is – should be shut down.

Q14. In a gas turbine engine oil temperature is measured:

as it leaves the fuel-cooled oil cooler (FCOC).

before entering the engine.

immediately after leaving the engine.

in the engine.

Correct answer is – as it leaves the fuel-cooled oil cooler (FCOC).

Q15. In a gas turbine engine oil pressure is measured:

in the engine.

in the return line.

after the pressure pump.

in the FCOC to ensure oil pressure is always above fuel pressure.

Correct answer is – after the pressure pump.

Q16. The magnetic chip detectors are fitted in:

the pressure line between the pressure pump and the engine.

suction line between the reservoir and the pressure pump.

return line between the engine and the scavenge pump.

return line after the FCOC.

Correct answer is – return line between the engine and the scavenge pump.

Q17. Gas turbines use:

wet sump and mineral oil.

dry sump and synthetic oil.

wet sump and synthetic oil.

dry sump and mineral oil.

Correct answer is – dry sump and synthetic oil.

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