An impulse coupling is installed on a magneto of a piston engine to ? [ Skills lift off ]

Question 43-1 : Provide a stronger spark on top dead centre for engine starting advance the ignition timing facilitate quick removal and installation absorb starting loads

exemple 143 Provide a stronger spark on top dead centre for engine starting. — The impulse coupling is a spring loaded mechanical coupling which delays rotation of the magneto during an engine start after a short period of rotation the device allows the magneto to catch up in effect spinning the mag shaft faster than the engine is turning it .the faster it turns the hotter the spark and the bigger the voltage impulse making for easier starting after the engine is running rotational forces move the spring loaded arms which make the impulse coupling work at low speeds out of the way the impulse coupling only works at very low engine speeds Provide a stronger spark on top dead centre for engine starting.

The part of a piston engine that transforms reciprocating movement into rotary ?

Question 43-2 : Crankshaft piston camshaft reduction gear

exemple 147 Crankshaft. — Img893 Crankshaft.

In a piston engine if the ratio of air to fuel is approximately 9 1 the mixture ?

Question 43-3 : Rich weak too weak to support combustion chemically correct

exemple 151 Rich. — Rich 9 1.correct 15 1.weak 20 1 Rich.

Spark plug fouling is more likely to happen if ?

Question 43-4 : The aircraft descends continuously at idle power the aircraft cruises at low speed with the correct mixture power is increased too abruptly the engine runs at maximum continuous power for too long

exemple 155 The aircraft descends continuously at idle power. — .plug fouling can occur due to rich mixtures with low cylinder temperatures this is the condition the engine will be in during descent at idle power .this is the reason during your flight training you are told not to let the engine run at idle rpm for too long normally you would increase rpm to around 1000 1200 rpm The aircraft descends continuously at idle power.

To maintain a constant mixture at low and high power settings in a piston ?

Question 43-5 : A diffuser compensating jet a power jet an accelerator pump a mixture control

exemple 159 A diffuser (compensating jet). — As engine speed and airflow through the venturi increase the proportion of fuel to air rises as a result of the different flow characteristics of the two fluids this causes the mixture to become richer .to overcome this effect some carburettors are fitted with a diffuser compensating jet .as engine speed is progressively increased above idling the fuel level in the diffuser well drops and progressively uncovers more air holes these holes allow more air into the discharge tube and by reducing the pressure differential prevent enrichment of the air/fuel mixture .the process of drawing both air and fuel through the discharge tube also has the effect of vaporising the fuel more readily particularly at low engine speeds A diffuser (compensating jet).

A piston engine may use a fuel of a different grade than the recommended ?

Question 43-6 : Provided that the grade is higher provided that the grade is lower never provided that it is an aeronautical petrol

exemple 163 Provided that the grade is higher — Provided that the grade is higher

In very cold weather the pilot notices during startup a slightly higher than ?

Question 43-7 : Is normal if it decreases after startup is abnormal and requires the engine to be shut down is abnormal but does not require the engine to be shut down requires an oil change

exemple 167 Is normal, if it decreases after startup. — Is normal, if it decreases after startup.

Excessive pressure in the cylinders of an engine equipped with a constant speed ?

Question 43-8 : High manifold pressure and low rpm low manifold pressure and low rpm high manifold pressure and high rpm low manifold pressure and high rpm

exemple 171 High manifold pressure and low rpm. — With constant speed control the pitch of the variable pitch propeller is changed automatically by a governor after the pilot sets the desired engine/propeller speed with the propeller speed control the governor acts to keep the propeller speed at the same value if the governor detects the propeller speed increasing it increases the pitch a little to bring the speed back within limits if the governor detects the propeller speed decreasing it decreases the pitch a little to bring the speed again back within limits this operation may be compared to an automatic gearbox in an automobile where the gears are changed automatically to keep the engine operating at a reasonable speed .during a power change on an engine equipped with a constant speed propeller a wrong combination of manifold pressure and rpm values results in excessive pressures in the cylinders this is the case when one simultaneously selects a high manifold pressure and low rpm High manifold pressure and low rpm.

When in flight a piston engine is stopped and the propeller blade angle is near ?

Question 43-9 : Feathered windmilling transparent at zero drag

The richness of a fuel/air mixture ratio is the ?

Question 43-10 : Real mixture ratio relative to the theoretical ratio volume of fuel relative to the volume of air volume of fuel relative to the mass of the volume of air mass of fuel relative to the volume of air

exemple 179 Real mixture ratio relative to the theoretical ratio. — As the name implies mixture refers to the ratio of fuel/air that goes into the cylinders of an engine for combustion for an internal combustion engine to operate it requires three things fuel air and ignition fuel and air are mixed in a ratio of approximately 15 1 15 parts of air to every 1 part of fuel to create combustion in a carbureted engine non fuel injected fuel and air are mixed in the carburetor before being introduced into the cylinders .carburetors are calibrated to operate with the mixture control set to 'full rich' when operating at sea level as the aircraft gains altitude it becomes necessary to reduce the amount of fuel entering the carburetor because the amount of air is automatically decreasing with altitude due to lower atmospheric pressure if the pilot fails to decrease the amount of fuel as altitude is gained the result will be an overly 'rich' mixture creating problems such as fouled spark plugs and excessive fuel consumption .overheating problems tend to occur when operating with an excessively lean mixture too little fuel a lean mixture creates better performance to a point as well as higher operating temperatures and reduces fuel consumption the problem arises when pilots fail to enrichen mixture add fuel as altitude is lost during a descent this results in an excessively lean mixture which can cause engine roughness fuel starvation and even permanent engine damage the point to remember is that fuel mixture must be decreased leaned as the aircraft climbs and increased enrichened as the aircraft descends it is also suggested to lean the mixture during ground operations at higher altitude airports generally above 3000 ft amsl .the term 'richness' refers to the 'real mixture ratio' relative to the 'theoretical mixture ratio' Real mixture ratio relative to the theoretical ratio.

Dual ignition provides a factor of reliability and ?

Question 43-11 : Improves combustion efficiency provides more voltage aids in starting saves wear caused by using one magneto constantly

exemple 183 Improves combustion efficiency. — Improves combustion efficiency.

With a piston engine when detonation is recognised you ?

Question 43-12 : Reduce manifold pressure and enrich the mixture increase manifold pressure and lean the mixture reduce manifold pressure and lean the mixture increase manifold pressure and enrich the mixture

exemple 187 Reduce manifold pressure and enrich the mixture. — The sudden release of heat energy from fuel in an aircraft engine caused by the fuel air mixture reaching its critical pressure and temperature .detonation occurs as a violent explosion rather than a smooth burning process .when detonation is recognized you should reduce manifold pressure and enrich the mixture .detonation can be caused by . too lean mixture. too high manifold pressure. using low grade fuel. an overheated engine Reduce manifold pressure and enrich the mixture.

'vapour lock' is the phenomenon by which ?

Question 43-13 : Heat produces vapour bubbles in the fuel line water vapour plugs are formed in the intake fuel line following the condensation of water in fuel tanks which have not been drained for sometime burnt gas plugs forming and remaining in the exhaust manifold following an overheat and thereby disturbing the exhaust abrupt and abnormal enrichment of the fuel/air mixture following an inappropriate use of carburettor heat

exemple 191 Heat produces vapour bubbles in the fuel line. — The vapour lock is a stoppage in a fuel feeding line caused by a fuel vapour bubble Heat produces vapour bubbles in the fuel line.

For a piston engine the chemically correct fuel/air ratio ?

Question 43-14 : Is 1 15 is 1 9 is 1 5 is 1 12

exemple 195 Is 1:15 — Rich 9 1.correct 15 1.weak 20 1 Is 1:15

The function of the primer pump in a reciprocating engine is to ?

Question 43-15 : Provide additional fuel for an engine start serve as an alternate pump in case of an engine driven pump failure to serve as main supply pump in a fuel injection system inject additional fuel during engine acceleration

exemple 199 Provide additional fuel for an engine start. — Provide additional fuel for an engine start.

One of the advantages of a turbocharger is ?

Question 43-16 : To make the power available less affected by altitude an increased propulsive efficiency that there is no torsion at the crankshaft that there is no danger of detonation

exemple 203 To make the power available less affected by altitude. — To make the power available less affected by altitude.

Assume an initial condition at a high cruise altitude with a constant speed ?

Question 43-17 : The manifold absolute pressure map value may exceed the maximum allowed value the power of the engine will decrease the blade angle may reach the full fine limit the manifold absolute pressure map value will stay constant

exemple 207 The manifold absolute pressure (map) value may exceed the maximum allowed value. — .with the engine producing power at low altitudes the turbocharger will be potentially over productive to prevent over boosting the wastegate will allow surplus exhaust energy to bypass the turbocharger at higher altitudes where the air is considerably less dense the wastegate will close off allowing the turbocharger to deliver the selected boost .during a descent from a high cruising altitude with the throttle fully open the turbocharger will be over productive and the manifold absolute pressure map value may exceed the maximum allowed value The manifold absolute pressure (map) value may exceed the maximum allowed value.

If the engine with a fixed pitch propeller is detonating during climb out after ?

Question 43-18 : Reduce the throttle increase the rate of climb lean the mixture apply carburettor heat

exemple 211 Reduce the throttle. — Reduce the throttle.

If when the magneto selector switch is set to the off position a piston engine ?

Question 43-19 : On a magneto the grounding wire is broken there is a carbon deposit on the spark plugs electrodes there are local hot points in the engine probably due to overheating of the cylinder heads a wire from the magneto is in contact with a metallic part of the engine

exemple 215 On a magneto, the grounding wire is broken. — The ignition system provides the spark that ignites the fuel/air mixture in the cylinders and is made up of magnetos spark plugs high tension leads and the ignition switch . 901.a magneto uses a permanent magnet to generate an electrical current completely independent of the aircraft's electrical system the magneto generates sufficiently high voltage to jump a spark across the spark plug gap in each cylinder the system begins to fire when you engage the starter and the crankshaft begins to turn it continues to operate whenever the crankshaft is rotating .most standard certificated airplanes incorporate a dual ignition system with two individual magnetos separate sets of wires and spark plugs to increase reliability of the ignition system each magneto operates independently to fire one of the two spark plugs in each cylinder the firing of two spark plugs improves combustion of the fuel/air mixture and results in a slightly higher power output if one of the magnetos fails the other is unaffected the engine will continue to operate normally although you can expect a slight decrease in engine power the same is true if one of the two spark plugs in a cylinder fails .the operation of the magneto is controlled in the cockpit by the ignition switch the switch has five positions .1 off.2 r right.3 l left.4 both.5 start.with right or left selected only the associated magneto is activated the system operates on both magnetos with both selected .you can identify a malfunctioning ignition system during the pretakeoff check by observing the decrease in rpm that occurs when you first move the ignition switch from both to right and then from both to left a small decrease in engine rpm is normal during this check around 100 to 150 rpm .if the engine stops running when you switch to one magneto or if the rpm drop exceeds the allowable limit do not fly the airplane until the problem is corrected the cause could be fouled plugs broken or shorted wires between the magneto and the plugs or improperly timed firing of the plugs it should be noted that 'no drop' in rpm is not normal and in that instance the airplane should not be flown .following engine shutdown turn the ignition switch to the off position even with the battery and master switches off the engine can fire and turn over if you leave the ignition switch on and the propeller is moved because the magneto requires no outside source of electrical power the potential for serious injury in this situation is obvious .loose or broken wires in the ignition system also can cause problems for example if the ignition switch is off the magneto may continue to fire if the ignition switch ground wire is disconnected if this occurs the only way to stop the engine is to move the mixture lever to the idle cutoff position then have the system checked by a qualified aviation maintenance technician On a magneto, the grounding wire is broken.

Ignition occurs in each cylinder of a four stroke engine tdc = top dead centre ?

Question 43-20 : Before tdc at each second crankshaft revolution before tdc at each crankshaft revolution behind tdc at each crankshaft revolution behind tdc at each second crankshaft revolution

exemple 219 Before tdc at each second crankshaft revolution. — Before tdc at each second crankshaft revolution.

The lubricating system of an air cooled piston engine is used to ?

Question 43-21 : Reduce internal friction and provide cooling keep the engine warm to operate the fuel control unit operate constant speed propellers

exemple 223 Reduce internal friction and provide cooling. — Reduce internal friction and provide cooling.

The first indication of carburettor icing in aeroplanes equipped with constant ?

Question 43-22 : Decrease in manifold pressure decrease in rpm rough running engine followed by an increase in manifold pressure rough running engine followed by loss in rpm

exemple 227 Decrease in manifold pressure. — On engines fitted with constant speed propellers a drop in power is indicated by a drop in manifold pressure the rpm remaining constant Decrease in manifold pressure.

The mixture control for a carburettor achieves its control by ?

Question 43-23 : Varying the fuel supply to the main discharge tube moves the butterfly valve through a separate linkage to the main throttle control altering the depression on the main discharge tube varying the air supply to the main discharge tube

exemple 231 Varying the fuel supply to the main discharge tube. — Varying the fuel supply to the main discharge tube.

The mechanism to change the propeller blade angle of a small piston engine ?

Question 43-24 : Hydraulically by engine oil hydraulically by hydraulic fluid manually by the pilot by aerodynamic forces

exemple 235 Hydraulically by engine oil. — Pdf656 Hydraulically by engine oil.

The use of too low an octane fuel may cause ?

Question 43-25 : Detonation higher manifold pressure a cooling effect on cylinders vapour locking

Which one of the following factors would be most likely to increase the ?

Question 43-26 : Using too lean a fuel/air mixture the use of a fuel with a high octane rating as compared to the use of one with a low octane rating using an engine with a low compression ratio slightly retarding the ignition timing

Detonation is nothing less than a series of small explosions that take place within an engine's combustion chambers it can be extremely destructive breaking pistons rod bearings and anything else from the pistons down that a large hammer could damage .weak air/fuel mixtures can result in very uneven mixtures within the chamber uneven burning pressure spikes and detonation

Vents in oil tanks are primarily to ?

Question 43-27 : Prevent excessive pressure from building up in tank prevent overthrow allow for expansion of hot oil eliminate foaming

exemple 247 Prevent excessive pressure from building up in tank. — Prevent excessive pressure from building up in tank.

The cylinder head and oil temperatures may exceed their normal operating ranges ?

Question 43-28 : A lower octane rating than specified for the engine is used a higher octane rating than specified for the engine is used the engine is operated at a higher than normal oil pressure the engine is operated at a too rich mixture

exemple 251 A lower octane rating than specified for the engine is used. — A lower octane rating than specified for the engine is used.

When starting the engine or when the engine is running at idle rpm on the ?

Question 43-29 : Rich to make starting possible and to cool the engine sufficiently when idling rich because the choke valve is closed rich because carburettor heat is switched on weak to prevent the engine consuming too much fuel

exemple 255 Rich, to make starting possible and to cool the engine sufficiently when idling. — Rich, to make starting possible and to cool the engine sufficiently when idling.

The cylinder head and oil temperature gauges are to exceed the normal operating ?

Question 43-30 : Uses fuel that has a rating lower than specified for the engine operates with the mixture control set too rich uses fuel that has a rating higher than specified for the engine operating with higher than normal oil pressure

exemple 259 Uses fuel that has a rating lower-than-specified for the engine — Uses fuel that has a rating lower-than-specified for the engine

The lubricating system of an aircraft engine is used to ?

Question 43-31 : Aid in dissipation of heat keep the engine warm operate ground adjustable propellers prevent inter crystalline corrosion

exemple 263 Aid in dissipation of heat — Aid in dissipation of heat

On design purpose the relationship between the fuel octane rating and the ?

Question 43-32 : The higher the octane rating is the higher the maximum compression ratio is the lower the octane rating is the higher the maximum compression ratio is the higher the octane rating is the lower the maximum compression ratio is the maximum compression ratio is independent of the octane rating

exemple 267 The higher the octane rating is, the higher the maximum compression ratio is — The higher the octane rating is, the higher the maximum compression ratio is

A magnetic plug in an engine oil system can be used to ?

Question 43-33 : Collect ferrous particles collect carbon found in the oil collect static electricity prevent metallic particles from entering the oil system

exemple 271 Collect ferrous particles. — The most basic type of magnetic filter is a drain plug where a magnet in the shape of a disc or cylinder is attached to its inside surface typically by adhesion periodically the magnetic plug is removed and inspected for ferromagnetic particles which are then wiped from the plug . 902.such plugs are commonly used in engine sumps gearboxes and occasionally in hydraulic reservoirs one useful advantage of mag plugs relates to examining the density of wear particles observed as a visual indication of the wear rate occurring within the machine over a fixed period of running time the appearance of these iron filings on magnets are often described in inspection reports using terms such as peach fuzz whiskers or christmas trees if one normally sees peach fuzz but on one occasion sees a christmas tree instead this would be a reportable condition requiring further inspection and remediation Collect ferrous particles.

Once the engine has started ignition systems of piston engines are ?

Question 43-34 : Independent of the electrical system of the aircraft dependent on the battery dependent on the dc generator dependent on the ac generator

exemple 275 Independent of the electrical system of the aircraft. — Independent of the electrical system of the aircraft.

The blade angle of a propeller is the angle between the ?

Question 43-35 : Reference chord line and the propeller plane of rotation reference chord line and the relative airflow reference chord line and the propeller axis of rotation plane of rotation and the relative airflow

exemple 279 Reference chord line and the propeller plane of rotation. — Blade angle usually measured in degrees is the angle between the chord of the blade and the propeller plane of rotation . 903 Reference chord line and the propeller plane of rotation.

In very cold weather a slightly higher than normal engine oil pressure during ?

Question 43-36 : Is acceptable if it decreases after startup is unacceptable and requires the engine to be shut down is unacceptable but does not require the engine to be shut down requires an oil change

exemple 283 Is acceptable, if it decreases after startup. — Is acceptable, if it decreases after startup.

Assuming the same swept volume and no turbo charger diesel engines compared to ?

Question 43-37 : Produce less maximum power output operate at higher exhaust gas temperatures show a higher fuel flow at the same power output produce a higher maximum power output

exemple 287 Produce less maximum power output. — Produce less maximum power output.

The operating principle of magnetos in a piston engine ignition system consists ?

Question 43-38 : Breaking the primary circuit in order to induce a low amperage high voltage current which is distributed to the spark plugs obtaining a high amperage low voltage current in order to generate the spark accumulating in a capacitor a low voltage current from the battery and inducing it as a high voltage current at the moment the spark is generated creating a brief high intensity magnetic field that will be sent through the distributor at the appropriate time

exemple 291 Breaking the primary circuit in order to induce a low amperage, high voltage current, which is distributed to the spark plugs. — Breaking the primary circuit in order to induce a low amperage, high voltage current, which is distributed to the spark plugs.

In a four stroke piston engine the only 'driving' stroke is ?

Question 43-39 : Power induction compression exhaust

Excessive priming of a piston engine should be avoided because .1 it drains the ?

Question 43-40 : 2 3 4 1 2 4 1 3 4 1 2 3

exemple 299 2, 3, 4. — .a fuel primer is a small hand pump designed to put neat fuel directly into either the induction manifold near the combustion chamber or the inlet valve port before you start in the cold promote the presence of fuel vapour that will ignite to start the engine .aside from the fire hazard excessive priming should be avoided because it fouls the spark plugs and there is a risk of flooding the engine 2, 3, 4.

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