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PPL AGK > ignition refined > Flashcards

ignition refined Flashcards

1
Q

aviation piston engines have dual ignition systems which means what?

A

there are two magnetos, which separately supply the electricity to a spark plug in each cylinder.

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2
Q

how many sparks plugs per cylinder?

A

2

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3
Q

why are there multiple spark plugs per cylinder?

A

in the event of failure of one system.

also provides smoother and more efficient combustion as there are two flame fronts.

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4
Q

what is a magneto?

A

component of a piston engine ignition system which provides the high voltage electricity necessary to power the spark plugs.

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5
Q

is the magneto independent or dependent on the aircraft’s electrical system?

A

independent.

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6
Q

what is a magneto made up of?

A

rotating magnet, primary coil, secondary coil and contact breaker.

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7
Q

how does a magneto work?

A

magnet spins generating magnetic force in the primary coil which is held back (doesn’t go to the secondary coil) by the primary coil.

when the contact point opens it allows the force to permeate the secondary coil which creates a high voltage in it provides electricity for igniting the spark plug.

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8
Q

what does a distributor do?

A

distributes electricity from the magnetos to the spark plugs in sequence which is then supplied with electric current and fires once every two revolutions of the crankshaft.

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9
Q

what do spark plugs do?

A

provide the spark in each cylinder.

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10
Q

what can happen if a spark plug has any damage or fouling?

A

reduce the efficiency of the spark provided to ignite the fuel-air mixture and will therefore produce less power.

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11
Q

what causes spark plug fouling?

A

many reasons. sometimes from low engine temperatures with low RPM or too rich a mixture or taxiing at low RPM for prolonged periods.

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12
Q

what is the best method for clearing spark plug fouling?

A

increasing power to 2000RPM for 60 seconds which can burn off any residue or carbon.

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13
Q

what is the purpose of impulse coupling?

A

to provide a short and sudden acceleration of the rotating magnet to generate a high voltage needed for engine start.

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14
Q

how does impulse coupling work?

A

it retards and delays the ignition timing to ensure that maximum pressure developed after TDC for start and immediately after allows the start time to return to normal.

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15
Q

how does a typical magneto system work?

A

typical is 4 cylinder engine with 2 spark plugs per. left magneto fires top plugs in cylinder 1 and 3 and bottom of 2 and 4 and vice versa for right magneto.

Any failures are fine as there’s a second magneto available but because only one spark plug will fire it won’t be as efficient and reduced power will be experienced.

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16
Q

what happens if an inserted key is selected to off?

A

both magnetos are grounded

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17
Q

what happens if an inserted key is selected to R?

A

right magneto is active and left is earthed meaning its still spinning but the electricity it produces is grounded.

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18
Q

what happens if an inserted key is selected to L?

A

leftt magneto is active and right is earthed meaning it’s still spinning but the electricity it produces is grounded.

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19
Q

what happens if an inserted key is selected to both?

A

both magnetos are providing power to the spark plugs.

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20
Q

if the spring-loaded start position is selected what happens?

A

usually only the left magneto is connected as it has the impulse coupling and there powers the spark plug that is connected to.

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21
Q

why shouldn’t you crank the starter for more than 10 seconds?

A

because doing so risks flattening the battery or damaging the starter motor.

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22
Q

what is the live cut check procedure?

A

turning the key from both to off briefly before returning back to both at 1000RPM or less.

23
Q

what is the purpose of doing a live cut check?

A

checking to see if the magnetos can be earthed meaning there’s no electricity from the magnetos being provided to the spark plugs meaning the engine will start to fail.

24
Q

what is the potential hazard surrounding live cut checks and what should you do about it?

A

potential that the engine continues to operate meaning the magnetos may provide enough electricity to power the spark plug.

shut down aircraft and avoid propellers for the potential startup.

25
Q

what is a dead cut check?

A

a check to see if you can isolate one magneto while still having the engine run on the other magneto.

26
Q

what is the purpose of doing a dead cut check?

A

to check the condition of each magneto.

27
Q

what is the potential hazard surrounding dead cut checks and what should you do about it?

A

if there is no drop in RPM this is an indication that one magneto hasn’t been earthed.

don’t go flying and shut down, be clear of propellers for a potential startup.

28
Q

what is the dead cut check procedure?

A

check each magneto by switching to Left and Right then go to a slightly higher RPM (1800) and perform another check to see that they’re both working fine.

29
Q

the contact breakers, distributor and impulse coupling in magneto ignition is replaced with what in solid-state ignition? (4)

A
  • capacitor
  • sensors for engine speed
  • crankshaft position
  • oxygen levels and compression
30
Q

how are all the things in a solid-state ignition controlled?

What is used to provide high voltage for spark plugs?

A

using a microprocessor that gets input about everything so it can just adjust the timing of the spark to ensure the best performance.

coil packs

31
Q

what are the advantages of a solid-state ignition? (4)

A
  • no moving parts for mechanical wear
  • no maintenance
  • reduction in EMP interference
  • can produce higher voltage for more efficient ignition
32
Q

what are the disadvantages of solid-state ignition? (3)

A
  • higher cost
  • can break down due to dirt moisture and vibration if poorly made
  • instead of parts slowly wearing down they just stop working
33
Q

unlike the magneto solid-state ignition requires what? and what does it do?

A

power supply.

supplies power to the engine but once it is running the system will draw power from the alternator instead of the battery.

34
Q

does the ignition system also need a power supply?

A

yes

35
Q

what happens if the alternator fails and there’s no power in the main or backup battery?

A

ignition system will not work and the engine will fail.

36
Q

what is the integrity check procedure?

A

check left and right systems, and check the backup emergency battery because its going to keep engine going a bit longer if alternator fails.

37
Q

what does an exhaust manifold do?

A

ducts away the combusted gas including carbon monoxide.

38
Q

why is it important for the exhaust manifold to be sealed properly?

A

because if there’s a leak carbon monoxide could enter the cockpit

39
Q

describe the possible sources, indications and associated danger of carbon monoxide gas.

A

the source is usually the exhaust system and if it has a leak.

the indication is through the use of a carbon monoxide detector which should be checked regularly for any signs.

it is dangerous because it’s undetectable by humans so the detector is the only way for it to be detected.

40
Q

why should you avoid rapid power changes?

A

moving throttle too quickly will change the amount of air passing through the carburettor and may not be able to keep up and maintain the correct fuel-air ratio making the engine cough.

41
Q

what does shock cooling engine do?

A

cool it too quickly and damage the engine, seen especially when in prolonged climb and the close the throttle to descend.

42
Q

what is the most common cause of rough running and how is it prevented?

A

carburettor icing

full carb heat should be applied or move out of icing conditions

43
Q

what procedure should you apply if rough running persists even with carb heat on?

A

carry out FMIIP

Fuel - confirm fuel pump on and tanks changed
mixture - full rich
ignition - select left magneto, cycle throttle to full and back and repeat for right
instruments - confirm fuel pressure/flow, oil temp and pressure
power - cycle throttle to full and back to idle if no power

44
Q

what if excessive vibration is experienced?

A

do not go flying and notify engineer.

45
Q

what does CHT and EGT gauges stand for and what do they do?

A

Cylinder head temperature and exhaust gas temperature which both help the pilot select the correct mixture.

46
Q

what is the most common cause of engine failure in flight?

A

fuel starvation, maybe from the wrong fuel tank selected or due to fuel blockage or fuel contamination.

47
Q

what should you do during engine failure?

A

close throttle, turn the fuel pump on, carb heat on and change fuel tanks.

if nothing works land at the nearest paddock and proceed with mayday procedures.

48
Q

What connects the magneto to the spark plugs?

A

High tension lead

49
Q

What is the purpose of the P lead?

A

To earth magnetos

50
Q

Precautions for hand swinging aircraft

A

Watch out for propellor, have someone in cockpit with park brake on and mags are live

51
Q

Procedure for starting the engine in cold temperatures

A

Use primer

52
Q

Procedure for starting overprimed engine

A

Start engine with lean mixture

53
Q

Procedure for controlling fire on startup

A

Mixture lean, throttle idle cutoff, pump off, fuel selector off and maybe turn on engine startup to burn remaining fuel

PPL AGK (29 decks)

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