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PPL Theory > Aircraft General Knowledge > Flashcards

Aircraft General Knowledge Flashcards

1
Q

What are the primary and secondary flight controls?

A

Primary - Elevator, Aileron, Rudder

Secondary - Flaps, Leading Edge Devices, Trim Tabs

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2
Q

How can flight controls be controlled?

A

Direct
Power Asissted (Hydraulics)
Fly-by-Wire

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3
Q

What are the types of stress placed on an airframe?

A

Tension
Compression
Torsion
Shear
Bending

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4
Q

What is meant by Elastic Limit?

A

The limit of distortion at which the structures returns to its original shape and dimensions

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5
Q

What is meant by Yield Point?

A

The point at which deformation becomes permanent

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6
Q

What is meant by Ultimate Load?

A

The load at which failure of the structure occurs

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7
Q

What is meant by Airframe life?

A

The number of cycles/hours the airframce can fly.

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8
Q

Which part of the aircraft structure supports the weight of the aircraft?

A

Wing Spar

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9
Q

What is a monocoque construction?

A

No internal bracing members, only formers and skin. The skin forms an integral part of the stress carrying structure. The skin is the main load carrier.

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10
Q

What is a semi-monocoque construction?

A

Base on monocoque, but makes use of stringers. A light-weoght frame covered by metallic stressed skin which shares the load carriying with the underlying structure.

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11
Q

What is the firewall?

A

The structure separating the engine compartment from the fuselage. Typically made out of stainless steel.

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12
Q

What are the three types of conventional trim?

A

Fixed (Ground Adjustable) Trim
Simple Trim
Spring Loaded Trim

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13
Q

What are the types of fuel tank?

A

Integral
Bladder
Wet Wing

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13
Q

What are fuel tank baffles?

A

Structures that restrict the free movement of fuel inside the fuel tanks. Prevents CoG moving excessively, fuel slamming around and fuel moving away from the pick-up pipe.

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14
Q

Describe Oleo Undercarriage

A

A chamber of gas and oil as a dampening shock absorber. Torque link keeos the wheel pointing in the right direction whilst allowing up and down movement of oleo.

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15
Q

What could happen to aircraft steering when oleo reaches full extension?

A

Typically when the oleo reaches full extension, the nose wheel will self centre and disengage from the rudder pedals.

This could mean more rudder is required during a cross wind takeoff.

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16
Q

What does the shimmy damper do?

A

Prevent nose wheel shimmy.

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17
Q

What can cause nosewheel shimmy?

A

Excessive play in or broken torque connection
Incorrect Tyre Pressure
Unevenly worn Tyres
Shimmy Damper fluid low
Nose Wheel bearings worn

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18
Q

What are ways to cope with nosewheel shimmy?

A

Descrease nosewheel load
Ease off braking
With Caution, when all else fails, full down elevator

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19
Q

How can over and underinflated tyres affect performance?

A

Over Inflated
Bounce on Landing
Excessive wear in the centre
Higher Aquaplaning speed

Under Inflated
Burst/Deflate on Landing
Increased tendency to creep
Excessive wear at the edges
Lower Aquaplaning speed

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20
Q

What is the most common type of aircraft brake?

A

Hydraulic Disc Toe Brakes

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21
Q

What are spats and why must caution be exercised?

A

Spats are wheel/tyre covers. Spats must be clean as any mud/grass can cause friction and reduced performance.

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22
Q

What are the gear limiting speeds?

A

Vlo = Max speed for gear operation
Vle = Max speed with gear extended

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23
Q

What are the properties of good hydraulic fluid?

A

Incompressible
Thermal Stability
Good Lubrication
Low Viscosity
Low Volatility
Non-Corrosive

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24
Q

What are the contents of a basic hydraulic system?

A

Reservoir
Pump
Accumulator
Selector Valve
Actuator
T&P Gauges

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25
Q

What are the two types of propeller?

A

Fixed Pitch
Variable Pitch

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26
Q

Describe the relationship between AoA and airspeed for a fixed pitch propeller

A

At a low forward speed, the relative AoA is high, which means it is hard work and RPM will be low.

At a high forward speed, the relative AoA is low, which means it is easier work and RPM will be high.

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27
Q

What is Fine and Coarse Pitch?

A

Fine Pitch - Low Blade Angle
Coarse Pitch - High Blade Angle

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28
Q

What happens to a Fixed Pitch Propeller in a climb?

A

Airspeed reduces, relative airflow angle increases, propeller is harder work, RPM reduces.

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29
Q

What is the CSU?

A

Constant Speed Unit. A mechanism that detects RPM change and adjusts propeller blade AoA to ensure the set RPM is maintained.

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30
Q

In what sequence should Power and RPM be changed?

A

To increase Power
Power UP
Increase RPM first
Increase Throttle Second

To reduce Power
Throttle BACK
Decrease Throttle First
Decrease RPM Second

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31
Q

What is the square and over-square rule of a Variable Pitch Prop?

A

Square Rule
A generic rule that conserves engine life and safer option. MAP equals RPM. Therefore 2000RPM = 20” MAP

Over-square
MAP never more than RPM + 4

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32
Q

What happens to CSU and Engine during climbs descents on a Variable Pitch Prop?

A

During a Descent
Static Pressure increases
MAP will also increase

During a Climb
Static Pressure decreases
MAP will also decrease

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33
Q

How should propeller be set during an engine failure?

A

Fully Coarse to allow the least drag

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34
Q

What are the 4 strokes of an otto cycle?

A

Intake
Compression
Power
Exhaust

Suck
Squeeze
Bang
Blow

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35
Q

What are the top and bottom positions of the cylinder known as?

A

Top Dead Centre (TDC)
Bottom Dead Centre (BDC)

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36
Q

What is the compression ratio?

A

The ratio between the volume of cylinder at BDC and TDC

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37
Q

What is the typical compression ratio of a Lycoming Piston Engine?

A

7:1

38
Q

Is a higher or lower compression ratio more efficient?

A

A higher compression ratio is more efficient. However the compression ratio is limited by the type of fuel used.

39
Q

Describe Pre-Ignition

A

The fuel/air mixture is ignited too early, before TDC. Caused by too low fuel octane, cylinder hotspots, high cylinder pressures.

To correct, mixture to full rich and reduce engine power.

40
Q

Describe Detonation

A

The fuel/air mixture is ignited too quickly and explodes. Caused by too low octane fuel, incorrect engine timing, incorrect fuel/air mixture or labouring engine.

To correct, mixture to full rich and reduce engine power.

41
Q

What are the five purposes of an aircraft oil system?

A

Lubrication
Sealing
Cooling
Cleaning
Protection

42
Q

What are the two types of oil?

A

“Straight” (S) Mineral oil. Typically only used for around 50 hours to wear in an engine.

“W” Ashless Dispersant Oil. Prevents corrosion and dissolves certain particles.

They must not be mixed.

43
Q

How does oil grade vary with temperature?

A

Higher grade numbers are thicker oil for a given temperature.

44
Q

What are the two types of Oil System?

A

Wet Sump
Dry Sump

45
Q

Describe a Wet Sump system

A

Oil collects at the bottom of an engine where it cools before being recirculated by the oil pump

46
Q

Describe a dry sump oil system

A

A scavenge pump collects oil from the lower parts of the system (small sump) and pumps the oil back to the oil tank, for it to be recirculated. Provides a larger oil supplu for large (typically radial) engines

47
Q

Where is the oil pressure sensor located?

A

Oil pressure sensor is located on the high pressure side of the oil distribution system. Ie after the oil pump.

48
Q

Is oil pressure after start important?

A

Yes. Oil pressure should be one of the first guages checkes after engine start. If oil pressure does not rise within 30 seconds, the engine must be shut down immediately.

49
Q

Where is the oil temperature sensor located?

A

Placed immediately after the oil cooler to monitor the cooled oil temperature.

50
Q

What is the correct order of oil flow for a typical light aircraft piston engine

A

Pump, Filter, Cooler, Pressure Sensor

51
Q

What are the grades and colours of aviation fuel?

A

AVGAS 80 - Red
AVGAS 100 - Green
AVGAS 100LL - Blue
Jet A - Colourless/Straw

52
Q

What is MOGAS?

A

Motor Gasoline, ie car petrol. Only allowed to be used when specified by the manufacturer. It is more flammable and explosive than 100LL.

53
Q

What are the two types of fuel system?

A

Gravity Fed
Pump Fed

54
Q

On a pump fed system, what pumps are there?

A

Mechanical Pump, driven by the engine.
Electric Pump, used as backup and for critical flight phases.

55
Q

What is the ideal ratio of fuel to air?

A

1:12

56
Q

What are the two different types of fuel air mixer?

A

Carburettor
Injection System

57
Q

How does a Carburettor work?

A

Carburettors use the venturi effect to to produce a pressure drop that sucks fuel into the airflow from the float chamber via a discharge nozzle.

58
Q

What happens to the carburettor as altitude increases but all else remains the same?

A

As altitude increases, density decreases. The carb will still allow the same amount of fuel through for a given setting. This results in the air/fuel mixture becoming rich. There will be less efficient burning of the mixture resulting in a reduction in power (RPM) and burn temperature.

Therefore, as the aircraft ascends, the mxture must be leaned.

59
Q

What is mixture control Idle Cut-Off?

A

When the mixture control is operated to fully lean, this cuts ALL fuel off to the discharge nozzle.

60
Q

What are the results of a mixture that is too rich?

A

The burn is not efficient (Cooler burn)
Power (RPM) reduces
The engine runs cooler
Spark plugs may begin to foul
Engine may stop if mixture becomes incombustible

61
Q

What are the results of a mixture that is too lean?

A

The burn is not efficient (Hotter Burn)
Power (RPM) reduces
The engine runs hotter
The mixture is prone to pre-ignition or detonation
Engine damage may result
Engine may stop if mixture becomes incombustible

62
Q

What is the approximate air temperature drop inside a carburettor and what is the problem?

A

Approximate drop of 25-30 degrees C through the carburettor Venturi. Carb Icing is the problem.

63
Q

What is Carb Icing?

A

Due to the temperature drop through the venturi, water droplets can freeze, forming ice in the venturi. This can restrict the mixture volume to the engine and/or restrict the movement of the butterfly valve (throttle)

64
Q

When is carb icing a concern?

A

Carb Icing can occur at any OAT when humidity is present. Humidity is the dominant factor. Therefore carb icing is more likely on warm days. It is also most likely to occur at descent power.

65
Q

What are symptoms of carb icing?

A

A gradually decreasing RPM (Fixed Pitch Prop)
A gradually decreasing MAP (Variable Pitch Prop)
Rough Running
Engine Failure

66
Q

How is carb ice dealt with?

A

Through carb heat. Intake air is switched to a warm source and the warm air melts the ice.

67
Q

What are the effects of carb heat?

A

Warm air melts the ice. Water will mix with the air/fuel mixture. The engine may initially run more rough. Once all ice melted and water removed, engine smoothness will be restored.

With carb heat providing the engine with less dense hot air, the engine will underperform.

68
Q

What are advantages and disadvantages of Fuel Injection?

A

Advantages
Reduction in evaporative Icing
Better fuel flow
Faster throttle response
Precise control of mixture
Better fuel distribution
Easier cold weather starts

Disadvantages
Difficulty in starting a hot engine
Vapour locks during ground operations on hot days
Problems associated with restarting an engine start stops because of fuel starvation

69
Q

What is the specific gravity of AVGAS?

A

0.72

70
Q

Describe Spark Plug Fouling

A

At low RPM or Rich mixture settings, any lead or carbon deposits that form are not burnt off. This causes an intermittent short circuiting of the plug gap, resulting in either a weak or no spark.

71
Q

What are the causes of spark plug fouling?

A

Long periods of low (idle) engine RPM
Operating in dusty environments
Failure to lean the mixture at idle in accordance with POH

72
Q

How does the ignition system ensure that it is fail-safe?

A

It will continue to work without any external electrical power. Only rotary motion is required, meaning the magneto will produce a spark so long as the engine is rotating. Also, if the grounding P-wire breaks the magneto can produce a spark, meaning it is fail-safe.

73
Q

How are magnetos prevented from sparking?

A

When the magneto switches are off, this connects the P-wire to Earth, meaning the magneto is grounded.

The P-wire must be connected. If the P-wire breaks the magneto can produce a spark, meaning it is fail-safe.

74
Q

Which magneto is conventionally the impulse magneto?

A

The left magneto

75
Q

In magneto “Run-Up” checks, what is being checked?

A

The maximum RPM drop for each magneto
The maximum difference in RPM drop between the two magnetos

76
Q

What are the voltage and capacities of batteries connected in parallel?

A

The overall system voltage remains the same
The capacity of the system is the sum of the battery capacities

77
Q

What are the voltage and capacities of batteries connected in series?

A

The overall system voltage is the sum of the voltages
The capacity of the system is the capacity of one battery

78
Q

How many times can a circuit breaker be reset in flight?

A

Once Only

79
Q

What caution should be exercised with the starter motor?

A

Very high current is drawn by the starter motor. Taking a toll on the battery
Engine cranking should be limited to 10 seconds to prevent battery/motor overheating
Sufficient recovery time between start attempts should be allowed to allow cooling

80
Q

Should the starter warning light be on or off after start?

A

After start, the starter warning light should be off. If it is on, it signifies the cog has not disengaged from the flywheel and the engine must be shut down immediately to prevent damage.

81
Q

What is the most effective way to cool an engine in flight?

A

Reduce power, ensure the mixture is rich and increase airspeed.

82
Q

How does the cowling affect cooling?

A

The engine cowl is designed to form an envelope around the engine to force the air around the cylinders.

83
Q

Which mixture helps engine cooling?

A

A rich mixture as this burns at a lower temperature.

84
Q

How is a centre-zero ammeter read?

A

Centred/0 means all electrical power is being supplied by the alternator and the battery is fully charged.

Right/Positive means all electrical power is being supplied by the alternator and the battery charging.

Left/Negative means the alternator is unable to supply all of the power requirements and battery is being used to compensate.

85
Q

What are the actions to take in the event of an Alternator failure?

A

Reduce electrical load to bare essentials. One Radio and nav lights if flying at night.
Inform ATC
Be prepared to use visual navigation
Be prepared for Radio Failure and what to do
Land as soon as practicable

86
Q

What does low oil pressure and high oil temperature mean?

A

Oil is probably being lost. The temperature is increasing since the remaining oil is being recirculated quicker, having less time to cool. In addition, because of the higher oil temperature, the oil becomes thinner and hence oil pressure reduces. Land ASAP.

87
Q

What does normal oil pressure but high/low oil temperature mean?

A

Oil Temperature and Pressure are related. So if one remains the same but the other changes, it is likely a malfunctioning guage, assuming the situation does not change. But exercise caution.

88
Q

What are the two types of fuel guages?

A

Float Type
Capacitance Type

89
Q

At what pitch and bank will an AI typically topple?

A

Pitch angles greater than 70 degrees
Bank angles greater than 110 degrees

90
Q

What does the turn indicator show?

A

RATE of turn. NOT bank.

91
Q

Is cockpit pressure higher or lower than outside atmospheric pressure?

A

Cockpit pressure is lower than outside atmospheric pressure in light aircraft.

92
Q
A

PPL Theory (5 decks)

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