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Which one of the following factors would be most likely to increase the ? [ Attestation AIM ]

Question 44-1 : High cylinder head temperature 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

exemple 144 High cylinder head temperature.High cylinder head temperature.

The octane rating of a fuel characterises the ?

Question 44-2 : Resistance to detonation fuel volatility quantity of heat generated by its combustion fuel electrical conductivity

The octane rating of fuel is a measure of its performance in engines a higher octane number means that the fuel and air mixture can withstand more compression before detonating premature detonation can result in an engine making knocking pinging or rattling sounds high octane fuel therefore helps reduce or eliminate knocking pinging or rattling in engines exemple 148 Resistance to detonation.Resistance to detonation.

Both gas turbine and piston engines use a cycle made up of induction ?

Question 44-3 : I is correct ii is correct i is incorrect ii is incorrect i is incorrect ii is correct i is correct ii is incorrect

Piston engine the combustion process is intermittent governed by the rythm of the back and forth movements of the piston in a cylinder the combustion occurs at constant volume in the cylinder .turbine engine the combustion process is continuous and occurs at constant pressure exemple 152 I is correct, ii is correct.I is correct, ii is correct.

When tas increases the blade angle of a constant speed propeller will rpm and ?

Question 44-4 : Increase decrease first decrease and after a short time increase to its previous value remain constant

On a propeller the relative airflow is the resultant of the airflow due to rotation and to the forward speed .a constant speed propeller automatically keeps the blade angle adjusted for maximum efficiency for most conditions encountered in flight so if tas or rpm change the blade angle will change .the blade angle 'pitch angle' if you prefer is a measurement of the distance between the propeller cord and the plane of rotation . 905.with an increasing tas the blade angle will increase .a propeller is similar to a screw . 906.if we want to enter quicky in a material we need the black screw high pitch if we want to go slowly the metalic screw small pitch is more convenient . 907.an efficient propeller is one which has the least amount of slippage and therefore converts more engine horsepower into thrust a constant speed propeller keeps the propeller pitch adjusted for maximum efficiency for most conditions of flight exemple 156 Increase.Increase.

With an aircraft fitted with a fixed pitch propeller during flight at normal ?

Question 44-5 : Loss of approximately 100 rpm an additional load on the other magneto excessive vibration the engine to overheat

exemple 160 Loss of approximately 100 rpm.Loss of approximately 100 rpm.

Both gas turbine and piston engines use a cycle made up of induction ?

Question 44-6 : I is incorrect ii is incorrect i is correct ii is correct i is incorrect ii is correct i is correct ii is incorrect

.piston engine the combustion process is intermittent governed by the rythm of the back and forth movements of the piston in a cylinder the combustion occurs at constant volume in the cylinder .turbine engine the combustion process is continuous and occurs at constant pressure exemple 164 I is incorrect, ii is incorrect.I is incorrect, ii is incorrect.

When excessively leaning the mixture for a better fuel economy but still on the ?

Question 44-7 : Cylinder head and exhaust gas temperature engine rpm oil temperature manifold pressure

exemple 168 Cylinder head and exhaust gas temperature.Cylinder head and exhaust gas temperature.

Both gas turbine and piston engines use a cycle made up of induction ?

Question 44-8 : I is incorrect ii is correct i is incorrect ii is incorrect i is correct ii is correct i is correct ii is incorrect

.piston engine the combustion process is intermittent governed by the rythm of the back and forth movements of the piston in a cylinder the combustion occurs at constant volume in the cylinder .turbine engine the combustion process is continuous and occurs at constant pressure exemple 172 I is incorrect, ii is correct.I is incorrect, ii is correct.

Given the following statements about diesel engines .1 power is set by the ?

Question 44-9 : 2 3 4 1 2 3 1 3 5 2 4 5

There is no mixture control and no throttle valve the power output of a diesel engine is controlled by regulating the quantity of fuel that is injected into the cylinder the amount of air is constant diesel engines are fitted with injectors not with valves exemple 176 2, 3, 4.2, 3, 4.

Diesel engines compared to petrol engines have ?

Question 44-10 : A higher compression ratio a lower compression ratio the same compression ratio a variable compression ratio

The power output of a diesel engine without a turbo charger is regulated by ?

Question 44-11 : Fuel flow only airflow only fuel flow and airflow mixture

On the gasoline engine the speed and power output is regulated by limiting the air and fuel mixture entering the engine the power output of a diesel engine is controlled by regulating the quantity of fuel that is injected into the cylinder the amount of air is constant exemple 184 Fuel flow only .Fuel flow only .

The ignition system of a running piston engine receives electrical energy from ?

Question 44-12 : Rotating permanent magnets batteries generators capacitors

The purpose of magnetic chip detectors is to ?

Question 44-13 : Warn of impending failure increase lubricating oil adhesion to main surfaces remove large items of debris from the system perform the function of a micron filter

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 . 663.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 exemple 192 Warn of impending failure.Warn of impending failure.

Apart from flight into known icing conditions the intake system of a diesel ?

Question 44-14 : Is never heated because a diesel engine is a injection engine needs to be heated to prevent ice on the air filter needs to be heated at low power settings due to vaporisation heat is never heated because diesel engines operate at very high temperatures

exemple 196 Is never heated because a diesel engine is a injection engine.Is never heated because a diesel engine is a injection engine.

The thermal efficiency of a diesel engine is higher than that of a petrol ?

Question 44-15 : The compression ratio is much higher the calorific value of the fuel is higher the egt is higher the air mass flow through the engine is higher

exemple 200 The compression ratio is much higher.The compression ratio is much higher.

Given the following statements about diesel engines .1 power is regulated by ?

Question 44-16 : 2 3 5 1 2 3 1 3 5 2 4 5

There is no mixture control and no throttle valve the power output of a diesel engine is controlled by regulating the quantity of fuel that is injected into the cylinder the amount of air is constant diesel engines are fitted with injectors not with valves exemple 204 2, 3, 5.2, 3, 5.

In liquid cooled engines the compostion by volume of coolant mixture is ?

Question 44-17 : 30% ethylene glycol and 70% water 60% ethylene glycol and 40% water 50% ethylene glycol and 50% water 65% ethylene glycol and 35% water

exemple 208 30% ethylene glycol and 70% water.30% ethylene glycol and 70% water.

The oil system for a piston engine incorporates an oil cooler that is fitted ?

Question 44-18 : In the return line to the oil tank after the oil has passed through the scavenge pump after the pressure pump but before the oil passes through the engine after the oil has passed through the engine and before it enters the sump between the oil tank and the pressure pump

exemple 212 In the return line to the oil tank after the oil has passed through the scavenge pump.In the return line to the oil tank after the oil has passed through the scavenge pump.

Diesel engines always produce a certain amount of soot because ?

Question 44-19 : The fuel droplets coming from the atomiser do not burn completely the mixture is always too rich the intake air is too cold the fuel droplets are too small

exemple 216 The fuel droplets coming from the atomiser do not burn completely.The fuel droplets coming from the atomiser do not burn completely.

What may happen during a continuous climb with a mixture setting fully rich ?

Question 44-20 : Fouling of spark plugs increase of the power available the engine will operate smoother even though fuel consumption is increased the engine will overheat

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 exemple 220 Fouling of spark plugs.Fouling of spark plugs.

Prolonged running at low rpm can have an adverse effect on the functioning of ?

Question 44-21 : Spark plugs carburettor oil pump fuel filter

exemple 224 Spark plugs.Spark plugs.

When leaning the mixture for the most economic cruise fuel flow excessive ?

Question 44-22 : High cylinder head temperature high engine rpm low cylinder head temperature high manifold pressure

Egt is relative to the temperature of the charge as it burns within the cylinder cht measures the temperature of the engine cylinder .the highest egt is achieved at a ratio of 15 parts of air to one part of fuel .if the ratio is reduced ie rich the charge temperature reduces due to excess fuel being left in the cylinder if the ratio is greater than 15 1 ie lean or weak the charge is cooled by excess air to appreciate why cht increases with lean mixtures we must consider the speed at which the fuel burns ie its flame rate lean mixtures burn slower than rich mixtures this means more heat is transferred to the engine components with lean mixtures .example if you move a lighted match quickly under your hand no problem but move it slowly and you will burn your hand slow burning lean mixtures will increase cht exemple 228 High cylinder head temperature.High cylinder head temperature.

During climb with constant throttle and rpm lever setting mixture being ?

Question 44-23 : Manifold absolute pressure map decreases rpm decreases manifold absolute pressure map increases rpm increases

The manifold absolute pressure map indicates the power output of a piston engine being a measure of the pressure of the fuel/air mixture in the inlet manifold .in an unsupercharged engine the reading will drop with height for a given throttle setting because there is less atmospheric pressure to push the useful charge into the cylinder exemple 232 Manifold absolute pressure (map) decreases.Manifold absolute pressure (map) decreases.

Both gas turbine and piston engines use a cycle made up of induction ?

Question 44-24 : I is correct ii is incorrect i is incorrect ii is incorrect i is incorrect ii is correct i is correct ii is correct

.piston engine the combustion process is intermittent governed by the rythm of the back and forth movements of the piston in a cylinder the combustion occurs at constant volume in the cylinder .turbine engine the combustion process is continuous and occurs at constant pressure exemple 236 I is correct, ii is incorrect.I is correct, ii is incorrect.

A piston engine compression ratio is the ratio of the ?

Question 44-25 : Total volume to the clearance volume clearance volume to the swept volume total volume to the swept volume swept volume to the clearance volume

Img897.compression ratio = volume at bottom dead total volume / volume at top dead clearance volume .the clearance volume is the volume that is not expelled from the cylinder exemple 240 Total volume to the clearance volume.Total volume to the clearance volume.

The purpose of a chip detector in the oil system of an engine/gearbox is to ?

Question 44-26 : There are metal particles in the oil the piston rings are worn the seals are worn the oil temperature is too high

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 ..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 exemple 244 There are metal particles in the oil.There are metal particles in the oil.

The thermal efficiency of a piston engine is about ?

Question 44-27 : 30% 50% 70% 80%

Thermal efficiency is the ratio of useful work to the heat put in expressed as a percentage .the first law of thermodynamics states that energy may be changed from one form to another but cannot be destroyed as far as engines are concerned it means that heat and mechanical work are mutually convertible and that the rate of exchande is constant and measurable .however the second law says more or less that 'heat flows from a hot substance to a cold one unaided but energy from an external source is needed for it to flow the other way' that is you might be able to convert most of your work into heat but turning heat into work will incur serious losses which is another way of saying that engines are grossly inefficient if it were otherwise exhausts would be cold .in fact engines waste as much energy in heat as the power they produce the approximate thermal efficiency of a four stroke engine is 30% exemple 248 30%.30%.

On a normally aspirated engine non turbo charged the manifold pressure gauge ?

Question 44-28 : A lower value than atmospheric pressure when the engine is running a value equal to the qfe when the engine is at full power on the ground a greater value than atmospheric pressure when the engine is running zero on the ground when the engine is stopped

Devidson .if the engine is on full power i e the butterfly valve is fully open the admision pressure would be equal to the atmospheric pressure on a non turbo charged engine no ..no matter how wide the butterfly throttle is opened there will always be some restriction hence the manifold pressure will always be lower than atmospheric even if only slightly exemple 252 A lower value than atmospheric pressure when the engine is running.A lower value than atmospheric pressure when the engine is running.

The purpose of a distributor in an ignition system is to distribute ?

Question 44-29 : Secondary current to the sparking plugs primary current to the condenser secondary current to the condenser primary current to the sparking plugs

.the purpose of the ignition system is to provide an ignition spark to the proper cylinder at the correct time in order to burn the compressed air/fuel mixture .it consists of two separate but closely related electrical circuits . low voltage primary circuit battery voltage . high voltage secondary circuit over 20000 volts .the ignition coil is the unit that takes your relatively weak battery power and turns it into a spark powerful enough to ignite fuel vapor inside a a traditional ignition coil are two coils of wire on top of each other these coils are called windings one winding is called the primary winding the other is the secondary the primary winding gets the juice together to make a spark and the secondary sends it out the door to the distributor .the distributor 'distributes' the secondary current to the sparking plugs exemple 256 Secondary current to the sparking plugs.Secondary current to the sparking plugs.

Viscosity is ?

Question 44-30 : The tendency of a liquid or gas to resist flow the temperature dependence of an oil the pressure resistance of an oil the flow velocity inside the oil lines

exemple 260 The tendency of a liquid or gas to resist flow.The tendency of a liquid or gas to resist flow.

With which instrument s do you monitor the power output of an aeroplane fitted ?

Question 44-31 : Rpm indicator fuel flow indicator rpm and map indicator cylinder head temperature indicator

exemple 264 Rpm indicator.Rpm indicator.

In a piston engine turbocharger boost pressure may be monitored by ?

Question 44-32 : A manifold pressure gauge only a cylinder head temperature gauge cht a manifold pressure gauge and engine rpm readings both a cht gauge and manifold pressure gauge both engine rpm readings and a manifold pressure gauge

exemple 268 A manifold pressure gauge only.A manifold pressure gauge only.

Fixed pitch propellers are usually designed for maximum efficiency at ?

Question 44-33 : Cruising speed idling full throttle take off

exemple 272 Cruising speedCruising speed

Overheating of a piston engine is likely to result from an excessively ?

Question 44-34 : Weak mixture rich mixture low barometric pressure high barometric pressure

Jaredleto .egt is relative to the temperature of the charge as it burns within the cylinder cht measures the temperature of the engine cylinder .the highest egt is achieved at a ratio of 15 parts of air to one part of fuel .if the ratio is reduced ie rich the charge temperature reduces due to excess fuel being left in the cylinder if the ratio is greater than 15 1 ie lean or weak the charge is cooled by excess air to appreciate why cht increases with lean mixtures we must consider the speed at which the fuel burns ie its flame rate lean mixtures burn slower than rich mixtures this means more heat is transferred to the engine components with lean mixtures .example if you move a lighted match quickly under your hand no problem but move it slowly and you will burn your hand slow burning lean mixtures will increase cht exemple 276 Weak mixture.Weak mixture.

In an engine equipped with a float type carburettor the low temperature that ?

Question 44-35 : Vaporization of fuel and expansion of the air in the carburettor freezing temperature of the air entering the carburettor compression of air at the carburettor venturi low volatility of aviation fuel

One disadvantage of the float type carburetor is its icing tendency the vaporization of fuel combined with the expansion of air as it flows through the carburetor causes a sudden cooling of the mixture the temperature of the air passing through the carburetor may drop significantly within a fraction of a second water vapor in the air is 'squeezed out' by this cooling and if the temperature in the carburetor reaches 0°c or below the moisture will be deposited as frost or ice inside the carburetor passages even a slight accumulation of this deposit will reduce power and may lead to complete engine failure particularly when the throttle is partly or fully closed . 1048.the formation of carburetor ice may reduce or block fuel/air flow to the engine exemple 280 Vaporization of fuel and expansion of the air in the carburettor.Vaporization of fuel and expansion of the air in the carburettor.

In addition to the fire hazard introduced excessive priming should be avoided ?

Question 44-36 : It fouls the spark plugs it washes the lubricant of cylinder walls it drains the carburettor float chamber the gasoline dilutes the oil and necessitates changing oil

exemple 284 It fouls the spark plugs.It fouls the spark plugs.

With respect to a piston engine aircraft ice in the carburettor ?

Question 44-37 : May form at oat's higher than +10°c will only form at oat's below +10°c will only form at outside air temperatures oat's below the freezing point of water will only form at oat's below the freezing point of fuel

exemple 288 May form at oat's higher than +10°c.May form at oat's higher than +10°c.

As the flight altitude increases if no leaning is made with the mixture control ?

Question 44-38 : The density of air entering the carburettor decreases and the amount of fuel remains constant the volume of air entering the carburettor remains constant and the amount of fuel decreases the volume of air entering the carburettor decreases and the amount of fuel decreases the density of air entering the carburettor decreases and the amount of fuel increases

.density decreases as we gain altitude but volume of air entering in the carburettor does not change as for the volume of fuel fuel density does not change with altitude exemple 292 The density of air entering the carburettor decreases and the amount of fuel remains constant.The density of air entering the carburettor decreases and the amount of fuel remains constant.

Cooling air for a reciprocating engine can be obtained by means of ?

Question 44-39 : Ram air a supercharger a turbocharger a pneumatic system

exemple 296 Ram airRam air

The main advantage of a constant speed propeller as compared to a fixed pitch ?

Question 44-40 : High efficiency in a much wider speed range of the aeroplane constant efficiency in the whole speed range of the aeroplane lower propeller blade stress higher efficiency in cruising range

.advantages of a constant speed propeller compared to a fixed pitch propeller .the power setting of a piston engine is defined by a combination of manifold pressure boost and rpm where separate power lever and rpm lever control is provided it is possible to vary one while leaving the other constant so optimising the operation of the engine/propeller combination to give best efficiency/fuel economy and least engine wear and tear in order to achieve this a 'variable pitch' propeller must be used enabling the pilot to select a propeller pitch and thus to vary rpm independently of manifold pressure provided that the propeller is operating between its internal fine and coarse pitch stops once an rpm has been selected a control unit csu constant speed unit or pcu propeller control unit will automatically vary the propeller pitch angle and therefore its angle of attack to the prevailing relative airflow in order to maintain the selected rpm despite airspeed and manifold pressure variations a constant speed propeller has a high efficiency in a much wider speed range than a fixed pitch propeller exemple 300 High efficiency in a much wider speed range of the aeroplane.High efficiency in a much wider speed range of the aeroplane.

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