'Vapour lock' is the phenomenon by which ?
Observation > CPL
For a piston engine the chemically correct fuel/air ratio ?
The function of the primer pump in a reciprocating engine is to ?
One of advantages of a turbocharger To make power available less affected altitude, an increased propulsive efficiency, that there no torsion at crankshaft, that there no danger of detonation. 
Assume an initial condition at a high cruise altitude with a constant speed propeller what will happen if altitude decreased while throttle remains fully open and waste gate seized in cruise position The manifold absolute pressure (map) value may exceed maximum allowed value, the power of engine will decrease, the blade angle may reach full fine limit, the manifold absolute pressure (map) value will stay constant. with engine producing power at low altitudes, turbocharger will be potentially over productive. to prevent over boosting, wastegate will allow surplus exhaust energy to bypass turbocharger. at higher altitudes, where air considerably less dense, wastegate will close off allowing turbocharger to deliver selected boost. during a descent from a high cruising altitude, with throttle fully open, turbocharger will be over productive the manifold absolute pressure (map) value may exceed maximum allowed value. 
If engine with a fixed pitch propeller detonating during climb out after takeoff normal corrective action would be to Reduce throttle, increase rate of climb, lean mixture, apply carburettor heat. 
If when magneto selector switch set to off position a piston engine continues to r normally most probable cause that On a magneto, grounding wire broken, there a carbon deposit on spark plugs electrodes, there are local hot points in engine (probably due to overheating of cylinder heads), a wire from magneto in contact with a metallic part of engine. The ignition system provides spark that ignites fuel/air mixture in cylinders is made up of magnetos, spark plugs, high tension leads, the ignition switch a magneto uses a permanent magnet to generate an electrical current completely independent of aircraft's electrical system. the magneto generates sufficiently high voltage to jump a spark across spark plug gap in each cylinder. the system begins to fire when you engage starter the crankshaft begins to turn. it continues to operate whenever crankshaft rotating. most standard certificated airplanes incorporate a dual ignition system with two individual magnetos, separate sets of wires, spark plugs to increase reliability of ignition system. each magneto operates independently to fire one of two spark plugs in each cylinder. the firing of two spark plugs improves combustion of fuel/air mixture results in a slightly higher power output. if one of magnetos fails, other unaffected. the engine will continue to operate normally, although you can expect a slight decrease in engine power. the same true if one of two spark plugs in a cylinder fails. the operation of magneto controlled in cockpit 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 associated magneto activated. the system operates on both magnetos with both selected. you can identify a malfunctioning ignition system during pretakeoff check observing decrease in rpm that occurs when you first move ignition switch from both to right, then from both to left. a small decrease in engine rpm normal during this check (around 100 to 150 rpm). if engine stops running when you switch to one magneto or if rpm drop exceeds allowable limit, do not fly airplane until problem corrected. the cause could be fouled plugs, broken or shorted wires between magneto the plugs, or improperly timed firing of plugs. it should be noted that 'no drop' in rpm not normal, in that instance, airplane should not be flown. following engine shutdown, turn ignition switch to off position. even with battery master switches off, engine can fire turn over if you leave ignition switch on the propeller moved because magneto requires no outside source of electrical power. the potential serious injury in this situation obvious. loose or broken wires in ignition system also can cause problems. for example, if ignition switch off, magneto may continue to fire if ignition switch ground wire disconnected. if this occurs, only way to stop engine to move mixture lever to idle cutoff position, then have system checked a qualified aviation maintenance technician. Question Piston Engines 29 Answer 8
Ignition occurs in each cylinder of a four stroke engine tdc = top dead centre 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. Question Piston Engines 29 Answer 9
The lubricating system of an air cooled piston engine used to Reduce internal friction provide cooling, keep engine warm, to operate fuel control unit, operate constant speed propellers. Question Piston Engines 29 Answer 10
The first indication of carburettor icing in aeroplanes equipped with constant speed propellers during cruise would most likely be a Decrease in manifold pressure, decrease in rpm, rough running engine followed an increase in manifold pressure, rough running engine followed loss in rpm. On engines fitted with constant speed propellers, a drop in power indicated a drop in manifold pressure, rpm remaining constant. Question Piston Engines 29 Answer 11
The mixture control a carburettor achieves its control Varying fuel supply to main discharge tube, moves butterfly valve through a separate linkage to main throttle control, altering depression on main discharge tube, varying air supply to main discharge tube. Question Piston Engines 29 Answer 12
The mechanism to change propeller blade angle of a small piston engine aeroplane in flight operated Hydraulically engine oil, hydraulically hydraulic fluid, manually the pilot, aerodynamic forces. Question Piston Engines 29 Answer 13
The use of too low an octane fuel may cause Detonation, higher manifold pressure, a cooling effect on cylinders, vapour locking. Question Piston Engines 29 Answer 14
Which one of following factors would be most likely to increase possibility of detonation occurring within a piston engine Using too lean a fuel/air mixture, use of a fuel with a high octane rating as compared to use of one with a low octane rating, using an engine with a low compression ratio, slightly retarding ignition timing. Detonation 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 anything else from pistons down that a large hammer could damage. weak air/fuel mixtures can result in very uneven mixtures within chamber, uneven burning, pressure spikes detonation. Question Piston Engines 29 Answer 15
Vents in oil tanks are primarily to Prevent excessive pressure from building up in tank, prevent overthrow, allow expansion of hot oil, eliminate foaming. Question Piston Engines 29 Answer 16
The cylinder head and oil temperatures may exceed their normal operating ranges if A lower octane rating than specified the engine used, a higher octane rating than specified the engine used, engine operated at a higher than normal oil pressure, engine operated at a too rich mixture. Question Piston Engines 29 Answer 17
When starting engine or when engine running at idle rpm on ground mixture Rich, to make starting possible to cool engine sufficiently when idling, rich, because choke valve closed, rich, because carburettor heat switched on, weak, to prevent engine consuming too much fuel. Question Piston Engines 29 Answer 18
The cylinder head and oil temperature gauges are to exceed normal operating ranges if a pilot Uses fuel that has a rating lower than specified the engine, operates with mixture control set too rich, uses fuel that has a rating higher than specified the engine, operating with higher than normal oil pressure Question Piston Engines 29 Answer 19
The lubricating system of an aircraft engine used to Aid in dissipation of heat, keep engine warm, operate ground adjustable propellers, prevent inter crystalline corrosion Question Piston Engines 29 Answer 20
On design purpose relationship between fuel octane rating and maximum compression ratio of a piston engine The higher octane rating is, higher maximum compression ratio is, lower octane rating is, higher maximum compression ratio is, higher octane rating is, lower maximum compression ratio is, maximum compression ratio independent of octane rating. Question Piston Engines 29 Answer 21
A magnetic plug in an engine oil system can be used to Collect ferrous particles, collect carbon found in oil, collect static electricity, prevent metallic particles from entering oil system. The most basic type of magnetic filter a drain plug, where a magnet in shape of a disc or cylinder attached to its inside surface (typically adhesion). periodically, magnetic plug removed inspected ferromagnetic particles, which are then wiped from plug. such plugs are commonly used in engine sumps, gearboxes occasionally in hydraulic reservoirs. one useful advantage of mag plugs relates to examining density of wear particles observed as a visual indication of wear rate occurring within 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 remediation. Question Piston Engines 29 Answer 22
Once engine has started ignition systems of piston engines are Independent of electrical system of aircraft, dependent on battery, dependent on dc generator, dependent on ac generator. Question Piston Engines 29 Answer 23
The blade angle of a propeller the angle between Reference chord line the propeller plane of rotation, reference chord line the relative airflow, reference chord line the propeller axis of rotation, plane of rotation the relative airflow. Blade angle, usually measured in degrees, the angle between chord of blade the propeller plane of rotation. Question Piston Engines 29 Answer 24
In very cold weather a slightly higher than normal engine oil pressure during startup Is acceptable, if it decreases after startup, unacceptable requires engine to be shut down, unacceptable but does not require engine to be shut down, requires an oil change. Question Piston Engines 29 Answer 25
Assuming same swept volume and no turbo charger diesel engines compared to petrol engines Produce less maximum power output, operate at higher exhaust gas temperatures, show a higher fuel flow at same power output, produce a higher maximum power output. Question Piston Engines 29 Answer 26
The operating principle of magnetos in a piston engine ignition system consists of Breaking primary circuit in order to induce a low amperage, high voltage current, which distributed to spark plugs, obtaining a high amperage, low voltage current in order to generate spark, accumulating in a capacitor a low voltage current from battery inducing it as a high voltage current at moment spark generated, creating a brief high intensity magnetic field that will be sent through distributor at appropriate time. Question Piston Engines 29 Answer 27
In a four stroke piston engine only 'driving' stroke Power, induction, compression, exhaust. Question Piston Engines 29 Answer 28
Excessive priming of a piston engine should be avoided because 1 it drains carburettor float chamber2 risk of engine fire 3 risk of flooding engine4 it fouls spark plugsthe combination that regroups all of correct statements 2, 3, 4,, 2, 4,, 3, 4,, 2, 3. a fuel primer a small hand pump designed to put neat fuel directly into either induction manifold (near combustion chamber) or inlet valve port before you start in cold promote presence of fuel vapour that will ignite to start engine. aside from fire hazard, excessive priming should be avoided because it fouls spark plugs there a risk of flooding engine. Question Piston Engines 29 Answer 29
Which one of following factors would be most likely to increase possibility of detonation occurring within a piston engine High cylinder head temperature, the use of a fuel with a high octane rating as compared to use of one with a low octane rating, using an engine with a low compression ratio, slightly retarding ignition timing. Question Piston Engines 29 Answer 30
The octane rating of a fuel characterises Resistance to detonation, fuel volatility, quantity of heat generated its combustion, fuel electrical conductivity. The octane rating of fuel a measure of its performance in engines. a higher octane number means that 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. Question Piston Engines 29 Answer 31
Both gas turbine and piston engines use a cycle made up of induction compression combustion and exhaust phases which of these statements about a piston engine are correct or incorrect i the process in a piston engine intermittent ii theoretically combustion occurs at constant volume I correct, ii correct, i incorrect, ii incorrect, i incorrect, ii correct, i correct, ii incorrect. Piston engine combustion process intermittent, governed the rythm of back forth movements of piston in a cylinder. the combustion occurs at constant volume in cylinder. turbine engine combustion process continuous occurs at constant pressure. Question Piston Engines 29 Answer 32
When tas increases blade angle of a constant speed propeller will rpm and throttle levers are not moved Increase, decrease, first decrease after a short time increase to its previous value, remain constant. On a propeller, relative airflow the resultant of airflow due to rotation to forward speed. a constant speed propeller automatically keeps blade angle adjusted maximum efficiency most conditions encountered in flight, so if tas or rpm change, blade angle will change. the blade angle ('pitch angle' if you prefer) a measurement of distance between propeller cord the plane of rotation. with an increasing tas, blade angle will increase. a propeller similar to a screw if we want to enter quicky in a material, we need black screw (high pitch). if we want to go slowly, metalic screw (small pitch) more convenient. an efficient propeller one which has least amount of slippage therefore converts more engine horsepower into thrust. a constant speed propeller keeps propeller pitch adjusted maximum efficiency most conditions of flight. Question Piston Engines 29 Answer 33
With an aircraft fitted with a fixed pitch propeller during flight at normal cruising speed one magneto fails completely this will first cause Loss of approximately rpm, an additional load on other magneto, excessive vibration, engine to overheat. Question Piston Engines 29 Answer 34
Both gas turbine and piston engines use a cycle made up of induction compression combustion and exhaust phases which of these statements about a piston engine are correct or incorrect i the process in a piston engine continuous ii theoretically combustion occurs at constant pressure I incorrect, ii incorrect, i correct, ii correct, i incorrect, ii correct, i correct, ii incorrect. piston engine combustion process intermittent, governed the rythm of back forth movements of piston in a cylinder. the combustion occurs at constant volume in cylinder. turbine engine combustion process continuous occurs at constant pressure. Question Piston Engines 29 Answer 35
When excessively leaning mixture a better fuel economy but still on rich side of peak egt following engine parameter s may exceed their normal operating ranges Cylinder head exhaust gas temperature, engine rpm, oil temperature, manifold pressure. Question Piston Engines 29 Answer 36
Both gas turbine and piston engines use a cycle made up of induction compression combustion and exhaust phases which of these statements about a piston engine are correct or incorrect i the process in a piston engine continuous ii theoretically combustion occurs at constant volume I incorrect, ii correct, i incorrect, ii incorrect, i correct, ii correct, i correct, ii incorrect. piston engine combustion process intermittent, governed the rythm of back forth movements of piston in a cylinder. the combustion occurs at constant volume in cylinder. turbine engine combustion process continuous occurs at constant pressure. Question Piston Engines 29 Answer 37
Given following statements about diesel engines 1 power set the mixture control 2 there no mixture control 3 amount of power determined the fuel flow only 4 thermal efficiency higher than that a petrol engine 5 diesel fuel more inflammable than petrol the combination that regroups all of correct statements 2, 3, 4,, 2, 3,, 3, 5, 2, 4, 5. There no mixture control no throttle valve, power output of a diesel engine controlled regulating quantity of fuel that injected into cylinder (the amount of air constant). diesel engines are fitted with injectors, not with valves. Question Piston Engines 29 Answer 38
Diesel engines compared to petrol engines have A higher compression ratio, a lower compression ratio, same compression ratio, a variable compression ratio. Question Piston Engines 29 Answer 39
The power output of a diesel engine without a turbo charger regulated Fuel flow only , airflow only, fuel flow airflow, mixture. On gasoline engine, speed power output regulated limiting air fuel mixture entering engine. the power output of a diesel engine controlled regulating quantity of fuel that injected into cylinder (the amount of air constant). Question Piston Engines 29 Answer 40
The ignition system of a running piston engine receives electrical energy from Rotating permanent magnets, batteries, generators, capacitors.
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