15. Gas turbine engine - Q&A

The primary purpose of the abradable lining in the fan case is to

• allow a minimum tip clearance without blade damage.
• reduce leakage of anti-icing air at the blade tips.
• provide an acoustic medium in the fan duct.

With inhibiting fluid fed to the fuel inlet, the fuel system of an installed engine is inhibited

• by running it at idle.
• by dry motoring the engine.
• by pumping it in statically.

The primary purpose of the abradable lining in the fan case is to

• allow a minimum tip clearance without blade damage.
• reduce leakage of anti-icing air at the blade tips.
• provide an acoustic medium in the fan duct.

A fuel or oil fire is defined as a

• class B fire.
• class C fire.
• class A fire.

Acoustic linings made from composite materials are used in what section of the engine?

• Not used to suppress noise.
• Hot section and Cold Section.
• Cold section only.

If a burner was down, in a multi-can system, the engine would tend to

• hang up.
• run up.
• surge.

The specific gravity of fuel affects

• thrust rating.
• aircraft range.
• engine efficiency.

Turboprop engine inlet anti-ice system operates

• continuously.
• cyclically dependant on weather conditions.
• cyclically independent on weather conditions.

The exhaust gas temperature (E.G.T ) indicator on a gas turbine engine provides a relative indication of the

• turbine inlet temperature.
• temperature of the exhaust gases as they pass the exhaust cone.
• exhaust temperature.

Nozzle guide vanes give a

• pressure increase, velocity decrease.
• pressure increase, velocity increase.
• pressure decrease, velocity increase.

An exhaust cone placed aft of the turbine in a jet engine will cause the pressure in the first part of the exhaust duct to

• increase and the velocity to decrease.
• decrease and the velocity to increase.
• increase and the velocity to increase.

In a choked nozzle, velocity increases, and

• density decreases.
• temperature increases.
• pressure increases.

Upon what quality or characteristic of a lubricating oil is its viscosity index based?

• Its rate of flow through an orifice at a standard temperature.
• Its rate of change in viscosity with temperature change.
• Its resistance to flow at a standard temperature as compared to high grade paraffin base oil at the same temperature.

The working fluid of a gas turbine engine is

• gasoline.
• kerosene.
• air.

Where do stress rupture cracks usually appear on turbine blades?

• Across the blade root, parallel to the fir tree.
• Across the leading or trailing edge at a right angle to the edge.
• Along the leading edge, parallel to the edge.

An H.M.U receives its signals from

• E.E.C.
• ADC.
• thrust lever resolvers.

Fire detection systems which are routed through another zone

• must be protected by the use of heat sinks.
• must be protected from heat sources in the zone.
• are not allowed.

Water methanol for cooling is injected into the

• compressor inlet or outlet.
• engine hot zone.
• combustion chamber.

Following the reports of a heavy landing you would

• carry out a complete visual examination of the power plant.
• examine the engine mountings and borescope the nozzle guide vanes and turbine.
• examine the engine mountings and fuse pins.

A scavenge filter is incorporated in a gas turbine lubrication system to

• protect the scavenge pump.
• protect the oil cooler.
• protect the pressure pump.

A ballast resistor is fitted

• in parallel, to give identical readings for all engines.
• in series, to give identical resistance values for all engines.
• in series, to give identical resistance values to all airframes.

The purpose of the rotating guide vanes on a centrifugal compressor is to

• direct the air smoothly into the impeller.
• provide initial diffusing of the air.
• prevent damage by solid objects.

For fire detection and extinguishing purposes, aircraft powerplant areas are divided into fire zones based on

• the volume and smoothness of the airflow through engine compartments.
• engine type and size.
• hot and cold sections of the engine.

Screech liners in the afterburning jet pipe

• prevent unstable combustion.
• prevent cyclic vibrations of large amplitude.
• acts as noise suppressors.

A small cut is found in an MVP engine storage bag. What is done about it?

• It is taped with adhesive PVC.
• A patch is vulcanised over it.
• The whole bag is replaced.