module 15 - part 2

What is a cannular combustion system?. One common flame tube closed in a common air casing. A set of flame tubes, each mounted in a separate air casing. A set of flame tubes, enclosed in a common air casing.

252) The flame temperature is approximately. 1400°Centigrade. 2000°Centigrade. 500°Centigrade.

253) Fuel entering the combustion chamber from an atomizer spray nozzle enters as. fuel in air pulses. a fuel/air mixture. fuel continuously.

254) An advantage of an annular combustion system is. unrestricted airflow at maximum RPM. diameter of engine is reduced due to the cans being smaller. decrease in combustor length compared to a tubo-annular combustor of the same output.

255) How is the combustion chamber drain valve closed?. By 12th stage compressor air pressure. By a return spring. By combustion chamber gas pressure.

256) Which statement is true regarding the air passing through the combustion section of a jet engine?. Most is used for engine cooling. Most is used to support combustion. A small percentage is frequently bled off at this point to be used for air-conditioning and/or other pneumatic powered systems.

257) How are combustion liner walls cooled in a gas turbine engine?. By secondary air flowing through the combustion chamber. By bleed air vented from the engine air inlet. By the pattern of holes and louvers cut in the diffuser section.

258) Dilution air is placed. in the dilution zone of the combustion chamber after the primary zone. in the primary zone of the combustion chamber. in the swirl vanes of the combustor.

259) A Duplex burner uses. small burner at low RPM and large burner at high RPM. small burner at low RPM and both burner at high RPM. both burners at low and high RPM.

260) The approximate percentage of the mass airflow which bypasses the flame tube snout is. 8%. 82%. 18%.

261) Flame stabilization in a combustion chamber is achieved by. the correct burner pressure. the airflow pattern. the correct air/fuel ratio.

262) Fuel nozzles are cleaned. with a rag and solvent. in-situ with carbon solution. in-situ with detergent solution.

263) When heat is added to the combustion chamber. pressure increases rapidly volume remains constant. pressure changes slightly and volume increases. pressure rises at chamber outlet.

264) A shroud placed around fuel nozzles. flakes the carbon to minimise accumulations. prevents carbon build up. builds up carbon deposits to assist atomisation.

265) Carbon forming on fuel spray nozzles will have the effect of. increasing the combustion chamber pressure ratio. producing turbulent air flow. changing the fuel spray angle.

266) Combustor air that is not used to support combustion. will film cool the liner and dilute combustion chamber exit temperature. is by-pass air. is considered as the total air flow.

267) At high rotational speed at sea level, a duple burner would be passing fuel via the. main nozzle. primary nozzle. primary and the main nozzle.

268) The fabricated liner of a flame tube is achieved mainly by. argon arc process. electric resistance welding. oxyacetylene welding.

269) Why is it necessary to have a combustion chamber drain?. To allow unburnt fuel to drain away. To prevent pressure build-up in the combustion chamber. To allow fuel to return to LP when H.P cock is closed.

270) The purpose of the swirl vanes in the combustion chamber is to produce. flame re-circulation. gas re-circulation. adequate mixing of fuel and air.

271) A vaporising burner injects fuel vapour. with the airflow. across the airflow. against the airflow.

272) A duplex burner in a gas turbine engine has 2 orifices. one for normal flow conditions and the 2nd one to increase the maximum flow. one for low speed conditions the second used for high speed conditions. one for water injection and one for fuel flow.

273) A combustion chamber has a. convergent inlet, divergent outlet. convergent inlet, convergent outlet. divergent inlet, convergent outlet.

274) The three main types of turbine blades are. impulse, vector, and impulse-vector. impulse, vector, and impulse-vector. impulse, reaction, and impulse-reaction.

275) What are the two main basic components of the turbine section in a gas turbine engine?. Stator and rotor. Hot and cold. Impeller and diffuser.

276) Turbine impulse blading forms a. constant area duct. divergent duct. convergent duct.

277) The turbine section. increases air velocity to create thrust. uses heat energy to expand and accelerate the gas flow. drives the compressor section.

278) 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.

279) What is meant by a shrouded turbine?. The turbine blades are shaped so that their ends form a band or shroud. The turbine wheel has a shroud or duct which provides cooling air to the turbine blades. The turbine wheel is enclosed by a protective shroud to contain the blades in case of failure.

280) Turbine nozzle diaphragms located on the upstream side of each turbine wheel, are used to. decrease the velocity of the heated gases flowing past this point. direct the flow of gases parallel to the vertical line of the turbine blades. increase the velocity of the heated gases flowing past this point.

281) Reduced blade vibration and improved airflow characteristics in turbines are brought by. shrouded turbine rotor blades. impulse type blades. fir tree blade attachment.

282) What term is used to describe a permanent and cumulative deformation of turbine blades?. Stretch. Creep. Distortion.

283) What is the major function of the turbine assembly in a turbojet engine?. Directs the gases in the proper direction to the tailpipe. Supplies the power to turn the compressor. Increases the temperature of the exhaust gases.

284) Gas pressure through the turbine section will generally. increase. remain the same. decrease.

285) Temperature through the turbine stages generally. remains the same. decreases. increases.

286) Shrouded blades allow. smaller inlets to be used. higher turbine inlet temperatures. thinner more efficient blade sections to be used.

287) Continued and/or excessive heat and centrifugal force on turbine engine rotor blades is likely to cause. galling. creep. profile.

288) Dirt particles in the air going into the compressor of a turbine engine will form a coating on all but which of the following?. Turbine blades. Casings. Inlet guide vanes.

289) Reduced blade vibration and improved airflow characteristics in gas turbines are brought about by. shrouded turbine rotor blades. fir tree blade attachment. impulse type blades.

290) A purpose of the shrouds on the turbine blades of an axial flow engine is to. reduce air entrance. increase tip speed. reduce vibration.

291) Hot section inspections for many modern turbine engines are required. on a time or cycle basis. only when an over temperature or overspeed has occurred. only at engine overhaul.

292) Why do some turbine engines have more than one turbine wheel attached to a single shaft?. To facilitate balancing of the turbine assembly. To extract more power from the exhaust gases than a single wheel can absorb. To help stabilize the pressure between the compressor and the turbine.

293) When aircraft turbine blades are subjected to excessive heat stress, what type of failures would you expect?. Bending and torsion. Stress rupture. Torsion and tension.

Which of the following conditions is usually not acceptable to any extent in turbine blades?. Cracks. Dents. Pits.

The forces driving a turbine round are due to. impulse only. reaction only. impulse and reaction.

Nozzle guide vanes give a. pressure increase, velocity decrease. pressure increase, velocity increase. pressure decrease, velocity increase.

Shrouding of stator blade tips is to. minimise vibration. ensure adequate cooling. prevent tip turbulence.

Why are two or more turbine wheels coupled?. To keep turbine rotor diameter small. So power output is doubled. To simplify dynamic balancing.

Running clearance on a turbine disk is kept to a minimum to reduce. temperature loss. aerodynamic buffeting. . tip losses.

Two basic types of turbine blades are. impulse and vector. reaction and impulse. tangential and reaction.

Why are nozzle guide vanes fitted?. To decrease velocity of the gas flow. To increase velocity of the gas flow. To increase velocity of the air flow.

A turbine disk is. a disk at the core of the engine that the blades are attached to. a segmented or complete shroud on blade tips that reduces leakage. a shroud around the stators of the turbine.

When carrying out a borescope the damage on turbine blades that would indicate a failure is. speckling. tip curl. colour changes.

The active clearance control system aids turbine engine efficiency by. automatically adjusting engine speed to maintain a desired EPR. adjusting stator vane position according to operating conditions and power requirements. ensuring turbine blade to engine case clearances are kept to a minimum by controlling case temperatures.

Turbine rear struts. straighten the gas flow. increase the velocity of the gas flow. increase the pressure of the gas flow.

Bowing of turbine blades indicates an. over-temperature condition. over-speed condition. under-temperature condition.

On an impulse-reaction turbine blade it is. impulse at the root and reaction at the tip. reaction at the root and impulse at the tip. impulse and reaction all the away along the blade.

Turbine creep effects. turbine blades. turbine disks. N.G.Vs.

Creep is. not found in turbines. a temporary deformation of turbine. a permanent deformation of turbine.

Creep, overall. has no effect on turbine diameter. increases turbine diameter. decreases turbine diameter.

How are turbine disks attached to the shaft in gas turbine engine?. Splined. Curvic couplings. Bolted.

Fir tree turbine blade attachment locates the blade. allows slight movement. radially. axially.

Creep may occur to turbine blades due to. prolonged low RPM use. over-temp with excessive centrifugal loads. high back pressures.

Forces driving the turbine are due to. aerodynamic lift imposing impulse on blades. momentum and directional acceleration of gases. expansion of gases.

Impulse turbine blades run cooler than reaction blades because. impulse spin faster radially. temperature drop across N.G.V is greater. converging rotors increase velocity.

An increase in turbine diameter is caused by. prolonged high temperatures and centrifugal loads. products of combustion. over speed.

Which of the following is most likely to occur in the turbine section of a gas turbine engine?. Pitting. Galling. Cracking.

Aluminium deposits on the turbine show up as. white or silver speckles. white powder traces. black stains.

An impulse/reaction turbine is designed to ensure. greater axial velocity at the blade root. uniform axial velocity from blade root to tip. greater axial velocity at the blade tip.

Excessive turbine temperatures can lead to. turbine blade creep and an increase in the diameter of the turbine. not a serious problem as long as engine oil pressure is within limits. a serious fire risk in the engine.

What are blue and golden deposits evidence of, on a turbine blade?. Titanium. Aluminium. Magnesium.

Necking and mottling of turbine blades. is due to thermal stress. is formed during manufacture. is due to bending when the gas hits the blades.

During a borescope check of the H.P turbine blades. dry motor the engine at minimum speed. hand turn the turbine wheel. attach a device to the accessory gearbox and rotate slowly.

The turbine section of a jet engine. converts dynamic pressure into mechanical energy. circulates air to cool the engine. extracts heat energy to drive the compressor.

The temperature and centrifugal loads which the turbine is subjected to during normal engine operation causes. fatigue failure. elastic stretching. creep loading.

Impulse-reaction turbine blades form. tip half reaction, root half Impulse. 1 stage impulse, 1 stage reaction. tip half Impulse, root half reaction.

A fir tree root. allows compressor cooling air to alleviate thermal stress. attaches turbine blades to the turbine disk. allows individual turbine blades to be changed without engine disassembly.

The passage between adjacent nozzle guide vanes forms a. convergent duct. divergent duct. parallel duct.

What is the normal range of turbine efficiency?. 90% - 95%. 70% - 85%. 30% - 40%.

Turbine engine components are never manufactured by. electrical resistance welding. argon arc welding. gas welding.

How is a radial turbine driven?. By impulse. By change of momentum and angle of airflow. By reaction.

Turbine disk growth is due to. a permanent change in disk diameter. an overall increase in blade length. a build up of carbon deposits.

A nozzle guide vane is. hollow in construction to allow for thermal expansion. hollow in construction to allow for flow of cooling air. solid in construction to support the guide vane.

A slow constant growth in a turbine blade is known as. primary creep. secondary creep. tertiary creep.

The function of the exhaust cone assembly of a turbine engine is to. swirl and collect the exhaust gases into a single exhaust jet. collect the exhaust gases and act as a noise suppressor. straighten and collect the exhaust gases into a solid exhaust jet.

The struts on the exhaust cone. straighten the gas flow only. support the exhaust cone and straighten the gas flow. support the exhaust cone only.

What is the maximum practical angle through which the gas flow can be turned during thrust reversal?. 180°. 50°. 135°.

A supersonic duct is. convergent then divergent along its length. divergent then convergent along its length. a convergent duct that is choked at the largest end at mach 1.

Noise from the jet wake when untreated by suppression is. high frequency, high decibel. low frequency, low decibel. low frequency, high decibel.

Hot spots on the tail cone of a turbine engine are possible indicators of a malfunctioning fuel nozzle or. a faulty igniter plug. an improperly positioned tail cone. a faulty combustion chamber.

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.

A convergent-divergent nozzle. requires the aircraft to be travelling at supersonic speeds. makes maximum use of pressure thrust. produces a type of thrust known as kinetic thrust.

The velocity of supersonic air as it flows through a divergent nozzle. is inversely proportional to the temperature. increases. decreases.

The velocity of supersonic air as it flows through a divergent nozzle. is inversely proportional to the temperature. increases. decreases.

The Jet Pipe of a gas turbine engine. protects the airframe from heat damage. has an inner cone to protect the rear turbine disc. is convergent in shape to increase the velocity as much as possible.

For what purpose is the propelling nozzle of a gas turbine engine designed?. To increase the velocity and decrease the pressure of the gas stream leaving the nozzle. To decrease the velocity and increase the pressure of the gas stream leaving the nozzle. To increase the velocity and pressure of the gas stream leaving the nozzle.

If the exit area of the nozzle was too large, the effect is. exit velocity lower causing loss of thrust. will choke at a lower gas temperature. exit velocity lower, negligible effect on thrust.

A choked nozzle. increases thrust. decreases thrust. has no effect on the thrust.

The exhaust section is designed to. increase temperature, therefore increasing velocity. decrease temperature, therefore decreasing pressure. impart a high exit velocity to the exhaust gases.

Reverse thrust can only be selected when the throttle is. closed. 75% power position. open.

A Convergent-Divergent nozzle. makes maximum use of Pressure thrust. produces a type of thrust known as kinetic thrust. requires the aircraft to be travelling at supersonic speeds.

On front fan engines, to obtain thrust reversal, the. hot and cold streams are reversed. hot stream is reversed. cold stream is reversed.

Exhaust noise can be reduced by. lowering the vibration frequency. increasing the mixing rate. increasing the jet velocity.

Operating thrust reversers at low ground speeds can sometimes cause. sand or other foreign object ingestion, hot gas re-ingestion. hot gas re-ingestion, compressor stalls. sand or other foreign object ingestion, hot gas re-ingestion, compressor stalls.

The purpose of cascade vanes in a thrust reversing system is to. turn the exhaust gases forward just after exiting the exhaust nozzle. form a solid blocking door in the jet exhaust path. turn to a forward direction the fan and/or hot exhaust gases that have been blocked from exiting through the exhaust nozzle.

A convergent exhaust nozzle produces mainly. momentum and pressure thrust. momentum thrust. pressure thrust.

The rearward thrust capability of an engine with the thrust reverser system deployed is. equal to or less than its forward capability, depending on ambient conditions and system design. less than its forward capability. equal to its forward capability.

Which statement is generally true regarding thrust reverser systems?. Engine thrust reversers on the same aircraft usually will not operate independently of each other (must all be simultaneously). It is possible to move some aircraft backward on the ground using reverse thrust. Mechanical blockage system design permits a deployment position aft of the exhaust nozzle only.

What is the proper operating sequence when using thrust reversers to slow an aircraft after landing?. Advance thrust levers up to takeoff position as conditions require, select thrust reverse, de- select thrust reverser, retard thrust levers to ground idle. Retard thrust levers to ground idle, raise thrust reverser levers as required, and retard thrust reverser levers to ground idle. Select thrust reverse, advance thrust reverser levers no higher than 75% N1, and retard thrust reverser levers to idle at approximately normal taxi speed.

Most exhaust system failures result from thermal fatigue cracking in the areas of stress concentration. This condition is usually caused by. the high temperatures at which the exhaust system operates. improper welding techniques during manufacture. the drastic temperature change which is encountered at altitude.

Thrust reversal on a high bypass engine is achieved by. blocker doors. clamshell configuration. bucket type doors.

If damage is found to the reverse thrust cascade vanes and they need replacing, you can. replace damaged vanes with 45 degree vanes. only replace vanes with new ones that have the correct part as the originals removed. interchange the cascade vanes as they are interchangeable.

When should thrust reversers be used?. At low RPM and low forward speed. At high RPM and high forward speed. At high RPM and low forward speed.

Lobe type exhaust noise suppressors are made from. heat resistant alloy. composite Material. steel.

What indication does the pilot receive that thrust reversers have deployed?. An audible warning. A sequence of lights. . A feeling of rapid deceleration.

What angle are the exhaust gasses turned through in a clamshell type thrust reverser?. 180 degrees. 135 degrees. 45 degrees.

The purpose of a propelling nozzle is to. increase the velocity of the air and increase thrust. decrease the velocity of the exhaust to increase static pressure. direct the air onto the turbines.

If a thrust reverser is deployed at lower than normal landing speed. exhaust gases can be ingested into the engine. the thrust reverser will be ineffective. if the EGT gets too high the thrust reverser will automatically restow.

The size of the exhaust section is dictated by. cone or diffuser size and location. size of engine only. size and location of the engine.

As the air flows out at the outflow of a choked nozzle. velocity increases and pressure decreases. velocity and pressure decrease. velocity decreases and pressure increases.

Main bearing oil seals used with turbine engines are usually what type(s)?. Teflon and synthetic rubber. Labyrinth and/or carbon rubbing. Labyrinth and/or silicone rubber.

If, during inspection at engine overhaul, ball or roller bearings are found to have magnetism but otherwise have no defects, they. are in an acceptable service condition. cannot be used again. must be degaussed before use.

A carbon seal has which type of sealing arrangement?. Full contact with race. Full contact with casing. Full contact with labyrinth.

The highest turbine bearing temperature takes place. all the time. at start-up. at shut-down.

Indentations on bearing races caused by high static loads are known as. fretting. galling. brinelling.

The function of a labyrinth seal is to create. a restricted leakage of air between fixed and rotating components. an airtight seal between fixed and rotation components. an airtight seal between fixed adjacent casing surfaces.

The bearings of a compressor rotor are usually. ball and roller. plain. sintered.

Bearing seal failure would most probably cause. high oil temperature. high oil consumption. low oil pressure.

Why are oil seals pressurised?. To ensure minimum oil loss. To ensure oil is forced into the bearings. To ensure that the oil is prevented from leaving the bearing housing.

What bearing is used to take axial loads on a main rotation shaft of a gas turbine engine?. Plain bearing. Roller bearing. Ball bearing.

Seals on a gas turbine engine restrict leakage of oil by. spring pressure. closely tolerated contacting components. air pressure.

An abradable lining in the fan case. prevents fan blade tip rub. produces less leakage at tips for anti-ice. provides acoustic medium.

Squeeze film bearings are usually found on. P compressor section. the turbine section. LP compressor section.

Taper roller bearings accept loads in which direction?. Axial loads only. Radial and axial in both directions. Radial and axial in one direction only.

Some labyrinth seals. control the outflow of air at the turbine. are self lubricating. are spring loaded.

In a jet engine the rotating assembly oil seals are maintained oil tight by means. a garter seal. an annular expander ring. air pressure.

Kerosene will burn effectively at an air/fuel ratio of. 150:1. 15:1. 45:1.

When using Prist or Biopor. it is left and burnt with the fuel. it is diluted with water to a 3-1 mix. it is flushed out immediately.

What is D.E.R.D 2494?. Oil. Wide cut gasoline. Kerosene.

A high viscosity index means the oil viscosity. will vary greatly with temperature change. has a large index number. will not vary greatly with temperature change.

A fuel system icing inhibitor is a fuel additive which. prevents both the water and the fuel freezing. prevents the fuel from freezing. prevents the water in the fuel freezing.

What will be the result of operating an engine in extremely high temperatures using a lubricant recommended by the manufacturer for a much lower temperature?. The oil pressure will be lower than normal. The oil temperature and oil pressure will be higher than normal. The oil pressure will be higher than normal.

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.

Compared to reciprocating engine oils, the types of oils used in turbine engines. are required to carry and disperse a higher level of combustion by-products. have less tendency to produce lacquer or coke. may permit a somewhat higher level of carbon formation in the engine.

If all other requirements can be met, what type of oil should be used to achieve theoretically perfect engine lubrication?. An oil that combines high viscosity and low demulsibility. The thinnest oil that will stay in place and maintain a reasonable film strength. An oil that combines a low viscosity index and a high neutralization number.

In addition to lubricating (reducing friction between moving parts), engine oil performs what functions?. Cools, seals, prevents corrosion. Cools, seals, prevents corrosion, cushions shock loads. Cools and seals.

The viscosity of a liquid is a measure of its. weight, or density. rate of change of internal friction with change in temperature. resistance to flow.

Which of the following factors helps determine the proper grade of oil to use in a particular engine?. Adequate lubrication in various attitudes of flight. Operating speeds of bearings. Positive introduction of oil to the bearings.

Specific gravity is a comparison of the weight of a substance to the weight of an equal volume of. oil at a specific temperature. mercury at a specific temperature. distilled water at a specific temperature.

What advantage do mineral base lubricants have over vegetable oil base lubricants when used in aircraft engines?. Cooling ability. Chemical stability. Friction resistance.

High tooth pressures and high rubbing velocities, such as occur with spur type gears, require the use of. an E.P lubricant. metallic ash detergent oil. straight mineral oil.

Which of these characteristics is desirable in turbine engine oil?. High volatility. High flash point. Low flash point.

What action is taken to protect integral fuel tanks from corrosion due to micro biological contamination?. Rubber liners are installed in the tank. A biocidal additive is added to the fuel. The inside of the tank is coated with yellow chromate.

What should be checked/changed to ensure the validity of a turbine engine performance check if an alternate fuel is to be used?. Maximum RPM adjustment. Fuel specific gravity setting. EPR gauge calibration.

Kerosene is used as turbine engine fuel because. kerosene has more heat energy per gallon and lubricates fuel system components. kerosene has very high volatility which aids in ignition and lubrication. kerosene does not contain any water.

Calorific value is the. amount of heat or energy in one pound of fuel. vaporisation point of fuel. fuel boiling temperature.

The specific gravity of fuel affects. thrust rating. aircraft range. engine efficiency.

Oil used in a gas turbine engine is usually. mineral. natural. synthetic.

An oil spectroscope measures. contaminants suspended in the oil. S.G. of the oil. contaminants in the surface of the oil.

Ignition of fuel depends upon. volatility. atomisation. both volatility and atomisation.

Kerosene is used instead of gasoline because. kerosene is highly volatile and has good lubrication qualities. Kerosene is less volatile and has good lubrication properties. kerosene has a higher volatility than gasoline and has good lubrication abilities.

If the specific gravity of a fuel is increased, the weight of a tank of fuel will. decrease. remain the same. increase.

Reid vapour pressure, is the vapour pressure exerted by a fuel when heated to. 38°C. 48°C. 15°C.

The oil pressure in the cooler is. same as the fuel pressure. lower than the fuel pressure. higher than the fuel pressure.

When rotating, the gear type oil pump. draws oil into the pump and carries it round between the gear teeth and casing. draws oil into the pump and through the intermeshing gears to the outlet. draws oil into the pump, half being carried around between pump and casing, the other half passing between the gears to the outlet.

A scavenge filter is incorporated in a gas turbine lubrication system to. protect the scavenge pump. protect the oil cooler. protect the pressure pump.

The working fluid of a constant speed drive (C.S.D) is. from separate tank. within the unit. taken from the engine lubrication system.

What is the possible cause when a turbine engine indicates no change in power setting parameters, but oil temperature is high?. High scavenge pump oil flow. Turbine damage and/or loss of turbine efficiency. Engine main bearing distress.

How is engine oil usually cooled?. By a fuel/oil cooler. By ram air. By bleed air.

What filters are used to protect oil pressure spray jets?. Felt/paper filters. In-line thread filters. Micronic filters.

The chip detector in the oil system is a. window in the pump casing. window in the oil pump. magnetic plug in the return line.

When rotating, the gyroter type oil pump. oil is drawn into the pump and through the intermeshing gears to the outlet. oil is drawn into the pump, half being carried around between pump and casing, the other half passing between the gears to the outlet. draws oil into the pump and carries it round between the gear teeth and casing.

Oil picks up the most heat from which of the following turbine engine components?. Compressor bearing. Rotor coupling. Turbine bearing.

In a jet engine which uses a fuel oil heat exchanger, the oil temperature is controlled by a thermostatic valve that regulates the flow of. both fuel and oil through the heat exchanger. oil through the heat exchanger. fuel through the heat exchanger.

What is the purpose of the last chance oil filters?. To filter the oil immediately before it enters the main bearings. To assure a clean supply of oil to the lubrication system. To prevent damage to the oil spray nozzle.

Which of the following is a function of the fuel oil heat exchanger on a turbojet engine?. Aerates the fuel. Emulsifies the oil. Increases fuel temperature.

At cruise RPM, some oil will flow through the relief valve of a gear type engine oil pump. This is normal as the relief valve is set at a pressure which is. higher than pressure pump capabilities. lower than the pressure pump capabilities. lower than the pump inlet pressure.

What will happen to the return oil if the oil line between the scavenger pump and the oil cooler separates?. Oil will accumulate in the engine. The scavenger return line check valve will close and force the oil to bypass directly to the intake side of the pressure pump. The return oil will be pumped overboard.

The oil dampened main bearing utilized in some turbine engines is used to. dampen surges in oil pressure to the bearings. provide lubrication of bearings from the beginning of starting rotation until normal oil pressure is established. provide an oil film between the outer race and the bearing housing in order to reduce vibration tendencies in the rotor system, and to allow for slight misalignment.

After making a welded repair to a pressurized type turbine engine oil tank, the tank should be pressure checked to. not less than 5 PSI plus the maximum operating pressure of the tank. not less than 5 PSI plus the average operating pressure of the tank. 5 PSI.

Possible failure related ferrous metal particles in turbine engine oil cause an (electrical) indicating type magnetic chip detector to indicate their presence by. bridging the gap between the detector center (positive) electrode and the ground electrode. generating a small electric current that is caused by the particles being in contact with the dissimilar metal of the detector tip. disturbing the magnetic lines of flux around the detector tip.

What would be the probable result if the oil system pressure relief valve should stick in the open position on a turbine engine?. Increased oil pressure. Decreased oil temperature. Insufficient lubrication.

What is the primary purpose of the oil to fuel heat exchanger?. De aerate the oil. Cool the oil. Cool the fuel.

What is the primary purpose of the oil breather pressurization system that is used on turbine engines?. Prevents foaming of the oil. Allows aeration of the oil for better lubrication because of the air/oil mist. Provides a proper oil spray pattern from the main bearing oil jets.

What type of oil system is usually found on turbine engines?. Dry sump, dip, and splash. Dry sump, pressure, and spray. Wet sump, spray, and splash.

How are the teeth of the gears in the accessory section of an engine normally lubricated?. By surrounding the load bearing portions with baffles or housings within which oil pressure can be maintained. By splashed or sprayed oil. By submerging the load bearing portions in oil.

The type of oil pumps most commonly used on turbine engines are classified as. positive displacement. constant speed. variable displacement.

If the oil in the oil cooler core and annular jacket becomes congealed, what unit prevents damage to the cooler?. Oil pressure relief valve. Airflow control valve. Surge protection valve.

What will result if an oil filter becomes completely blocked?. Oil flow to the engine will stop. Oil will flow at the normal rate through the system. Oil will flow at a reduced rate through the system.

A turbine engine dry sump lubrication system of the self contained, high pressure design. stores oil in the engine crankcase. has no heat exchanger. consists of pressure, breather, and scavenge subsystems.

What is the primary purpose of the hopper located in the oil supply tank of some dry sump engine installations?. To reduce the time required to warm the oil to operating temperatures. To impart a centrifugal motion to the oil entering the tank so that the foreign particles in the oil will separate more readily. To reduce surface aeration of the hot oil and thus reduce oxidation and the formation of sludge and varnish.

A full flow oil system has. a single fixed minimum oil pressure. a variable oil pressure dependant upon throttle setting. a hot and cold oil pressure limit.

A felt filter in an oil lubrication system should be. removed and cleaned in M.E.K. removed and replaced with a new filter element. removed and cleaned in a container of lead free petrol.

What filter is used in a oil scavenge pump in the inlet side of the pump?. Wire wound filter. Threaded filter. Wire mesh filter.

A vane type oil pump output is controlled by. outlet pressure against spring pressure. outlet pressure controlling servo. output pressure controlling plate angle.

The sump in a dry sump oil system. is used as a collecting point only. houses all the engine oil. provides lubrication for the main bearings.

A jet engine gear box breather is prevented from leaking oil to atmosphere by the action of. air or oil valve. oil thrower ring and centrifugal force. impeller and centrifugal force.

The air-cooled-oil-cooler has an anti-surge valve in order to. protect the cooler. restrict the engine max oil pressure. stop oil draining from the system when the cooler is removed.

A thread type oil seal in a lubrication system. screws oil back into the bearing sump when the shaft rotates. has a thread on a stationary portion to prevent fluid leaks. only seals when stationary.

The oil system generally used on most modern turboprop engines is. dry sump type. wet sump type. A low pressure system.

A spur gear pump operating in a lubrication system promotes. high flow at low pressure. low flow at low pressure. low flow at high pressure.

If the swash plate of a positive displacement swash plate pump is perpendicular to the axis of the pump, the flow will be. reversed. zero. maximum.

What moves the swash plate away from the minimum stroke position?. Reduced inlet pressure. A spring. Increased servo pressure.

The burner fuel flow is at maximum at. 10°Centigrade above I.S.A. sea level. S.A. sea level. altitude.

What would be the effect on the engine if the B.P.C half ball valve in the servo line sticks open?. A reduction of fuel flow, therefore a decrease in RPM . The B.P.C would be ineffective at sea level only. An increase of fuel flow, therefore an increase in RPM .

Why is an A.C.U fitted to a gas turbine engine?. It increases the rate of acceleration of the engine. It controls the operation of the metering block during sudden acceleration. It limits the rate of increase in fuel flow during sudden acceleration.

If fuel pump servo pressure is reduced, pump output will. increase. decrease. remain constant.

Why is the B.P.C fitted in a gas turbine engine fuel system?. To vary pressure pump output in relation to the pressure variation at the intake. To proportion the fuel flow between primary and main burner lines. To decrease the fuel flow to the burners with increased air intake pressure.

What must be done after the fuel control unit has been replaced on an aircraft gas turbine engine?. You must recalibrate the fuel nozzles. You must retrim the engine. You must perform a full power engine run to check fuel flow.

A kinetic valve is a device used to control H.P pump output. This is achieved by movement of a. needle valve. diaphragm and half ball valve. knife blade.

Specific fuel consumption at altitude will. decrease. remain constant. increase.

During any stabilised running condition, the spill or half ball valve is. lightly seated. closed fully. open fully.

What is the purpose of the attenuator fitted between the H.P fuel pump and the P.C in a fuel system?. It restricts the pressure feed top the B.P.C. It ensures a supply of fuel free from foreign matter to the BC half ball valve. It damps out pulsations in the fuel delivery to the B.P.C.

Why is the hydromechanical governor fitted to a gas turbine engine fuel pump?. To enable the engine to operate over a wide range of fuel SGs. To enable efficient control of fuel flow to be maintained at altitude. To enable the engine to operate over a wide range of fuel flow.

A barometric Pressure Controller controls. barometric pressure. fuel flow to suit atmospheric pressure changes. fuel tank pressure at altitude.

Kinetic valves are used because. they are less likely to leak. they are more sensitive. they are not subjected to wear.

When considering a centrifugal type engine speed governor, an increase in fuel S.G. will cause. no change in maximum RPM. an increase in maximum RPM. a reduction in maximum RPM.

On a FADEC engine. A channel uses control alternator and B channel uses aircraft bus power. A channel uses a separate winding of the control alternator to B channel. A and B channel use the same phases of the motor.

Normal fuel/air ratio for successful combustion is. 15:1. 25:1. 10:1.

Which of the following influences the operation of an automatic fuel control unit on a turbojet engine?. Exhaust gas temperature. Mixture control position. Burner pressure.

What is the purpose of the L.P. pump?. To ensure rapid acceleration when the throttle is opened. To prevent cavitation of the H.P Fuel pump. To ensure the engine will continue to run if the H.P. fuel pump fails.

The fuel pump plungers are lubricated by. synthetic anti-freeze oil. grease packed bearings. the Fuel.

Which forces control the maximum RPM governor in a non-hydromechanical swashplate type of pump?. Rotor centrifugal pressure opposed to tension spring loading. Rotor centrifugal pressure plus tension spring loading opposed to pump delivery pressure. Rotor centrifugal pressure plus tension spring loading opposed to pump inlet pressure.

Why do the holes in the body of the duple burner provide air to the shroud around the burner head?. To reduce burner temperature. To assist atomisation of the fuel at slow running. To minimise carbon formation on the burner face.

A fuel heater prevents. neither. LP filter icing. P filter icing.

On a FADEC engine the E.E.C. has electronic control of the hydro-mechanical fuel control in some modes. has mechanical control of the hydro-mechanical fuel control system. has electronic control of the hydro-mechanical fuel control unit in all modes.

During normal running conditions, combustion is. continuously supported by ignition. self supporting. intermittently supported by ignition.

On a FADEC engine, the channel reset. always selects A channel. selects B channel. selects standby which becomes active on the next start.

With a decrease in fuel SG, what is the result when the engine is fitted with an uncompensated fuel governor?. No effect. Maximum RPM decrease. Maximum RPM increase.

The maximum RPM of a turbine engine is limited by. a temperature sensitive device which reduces the fuel pump speed. diversion of some of the fuel pump outlet flow by a spill valve sensitive to burner fuel pressure. reduction of the fuel pump stroke by a spill valve sensitive to centrifugally generated fuel pressure.

During acceleration, the fuel flow is increased at a controlled rate in order to. prevent fuel pump damage. increase s.f.c. prevent surge and the risk of flame-out.

The B.P.C controls the F.C.U by. pressure sensing. temperature sensing. density sensing.

If the swash plate of a positive displacement swash plate pump is perpendicular to the axis of the pump, the flow will be. zero. reversed. maximum.

The burner fuel flow is at maximum at. altitude. 10°Centigrade above I.S.A. sea level. S.A. sea level.

The type of fuel control unit most commonly used in modern jet engines is. mechanical. hydro-mechanical. electrical.

How is servo pressure, which is used to control fuel pump swash plate angle, obtained?. From pump inlet pressure through fixed restrictions. From pump delivery pressure through fixed restrictions. From pump delivery pressure through variable restrictions.

Why is the Barometric Pressure Control fitted in a turboshaft engine fuel system?. To proportion the fuel flow between primary and main burner lines. To vary pressure pump output in relation to the pressure variation at the intake. To decrease the fuel flow to the burners with increased air intake pressure.

During any stabilised running condition, the spill or half ball valve is. always varying between fully closed and fully seated. lightly seated. open fully.

The swash plate in a fuel pump, when static is. at some intermediate position. in the minimum position. in the maximum position.

A kinetic valve is a device used to control H.P pump output. This is achieved by movement of a. diaphragm and half ball valve. knife blade. needle valve.

Why is it necessary to control fuel supply to the engine during rapid acceleration?. To prevent compressor stall above cruise RPM. To control maximum RPM. To prevent excessively high EGT and possible compressor surge.

Which component corrects for air density effects on fuel/air mixture in a gas turbine engine?. The barometric pressure control unit. The adjustable throttle valve. The pressurising valve.

Why is the high pressure fuel pump fitted in a gas turbine engine aircraft?. To maintain a vapour free pressure from the aircraft fuel tanks to the LP fuel pump. As an emergency in case of failure of the LP pump. To provide the majority of the fuel pressure to the engine.

What are the positions of the pressurization valve and the dump valve in a jet engine fuel system when the engine is shut down?. Pressurization valve open, dump valve open. Pressurization valve closed, dump valve open. Pressurization valve closed, dump valve closed.