Systems Flashcards
1
Q
What is the purpose of a carburetor?
A
Mix the fuel and air in correct ratio and deliver that mixture to the cylinders
2
Q
What happens when the butterfly valve opens?
A
Airflow through the Venturi accelerates, causing lower static pressure. The pressure differential between the float chamber and Venturi will increase and more fuel will flow into the carburettor
3
Q
What are the three types of carburettor icing?
A
Fuel icing
Throttle icing
Impact icing
4
Q
What are the conditions conducive to carburettor icing?
A
OAT below 30 degrees
Relative humidity above 80%
Low power settings for a long time
5
Q
What do symptoms of carburettor icing include?
A
Partial or total loss of power
Degraded engine performance
Rough running
6
Q
What can fuel icing also be referred to as?
A
Refrigeration icing
7
Q
When does impact icing occur?
A
Super cooled water droplets hit the metal surfaces of the air intake to the fuel system
8
Q
What conditions are for impact icing?
A
OAT close to or below zero
Aircraft is in visible moisture
9
Q
What causes fuel icing?
A
Fuel vaporisation and cooling as it is mixed with the airflow in the carburettor
10
Q
When can fuel icing occur?
A
OAT up to 20 degrees
Average to relatively high humidity
11
Q
What causes throttle icing?
A
Cooling effects that result from air accelerating around the butterfly valve inside the carburettor
12
Q
Is visible moisture required for throttle icing?
A
No
13
Q
When should carby heat be used in icing conditions?
A
Full, intermittently
14
Q
What is the most common fuel injection system?
A
Continuous flow injection system
15
Q
Where is fuel injected by the fuel injection system?
A
Intake valve chamber for each cylinder
16
Q
What is a supercharger used for?
A
Compensate for reduced density at altitude by maintaining power available at sea level
Boost the manifold pressure at sea level to a value above the normal sea level atmospheric pressure
17
Q
What is turbo normalising?
A
Compressed air is pumped into the intake manifold to allow the engine to burn extra fuel and so produce extra power at altitudes where normally aspirated would struggle
18
Q
What are the three types of wastegate?
A
Fixed
Manual
Automatic
19
Q
What is full throttle height in a supercharged engine?
A
The altitude at which the rated boost is available at a certain RPM
20
Q
What is the critical altitude?
A
The highest altitude at which maximum rated power can be obtained with full throttle
21
Q
Advantages of fuel injection over carburetors?
A
Mixture strength can be controlled more precisely
Fuel is injected immediately adjacent to the intake valve
No icing problems
Fuel is distributed more evenly within the cylinders
22
Q
What does the voltage regulator do?
A
Maintains correct voltage output from the alternator
23
Q
Batteries in series give what?
A
Higher power
24
Q
What is the alternator output voltage the same as?
A
The electrical system voltage
25
What kind of current does the alternator generate?
AC current
26
What is it that converts AC to DC power?
Rectifier
27
What converts DC to AC?
Inverter
28
How is it ensured the alternator powers the electrical system and not the battery?
Alternator output voltage is slightly higher
29
For a centre zero ammeter, what will you see directly after start and why?
A large plus as the alternator comes online and begins charging the drained battery
30
What would a large plus indicate on a centre zero ammeter in flight?
Could indicate an electrical system problem - however definitely indicates the battery is supplying power
31
What does a load type ammeter measure?
Alternator output
32
If you saw zero on a left zero ammeter, how would you determine alternator failure or no alternator load?
Turn equipment on to see if load goes up - if not suspect alternator failure
33
What does a voltmeter indicate?
How many volts are being supplied to the bus bar
34
In a 28V electrical system, what does a voltmeter indication of 24V indicate?
Battery is supplying the bus bar
35
Which way does propeller thrust reaction act?
Perpendicular to the plane of rotation
36
Which way does the propeller torque reaction act?
In the plane of rotation
37
Which way does the plane of rotation of a propeller work?
Perpendicular to the crankshaft
38
Propeller angle of attack?
Angle between the propellers chord and the relative airflow
39
What is the propeller blade angle?
The angle between the chord line and the plane of rotation
40
What is the helix angle?
Angle between the plane of rotation and the relative airflow
41
What is indicated horsepower?
Horsepower available at the cylinders
42
What does IHP indicate?
How much heat energy in the fuel is converted to mechanical energy
43
What is brake horsepower?
A measure of the useful work done by a piston engine
44
How is BHP determined?
IHP minus the power absorbed in the engine by friction and by driving the engine itself
45
What is friction horsepower?
The part of IHP that is absorbed by friction and driving the valves, ignition, lubrication systems etc
46
At a given RPM for a fixed pitch propeller, what happens between TAS and AoA?
Increase TAS = reduce the AoA
Lower TAS = higher AoA
47
At a given TAS for a fixed pitch propeller, what is the relationship between RPM and AoA?
Increase RPM = increase AoA
Lower RPM = smaller AoA
48
What do counterweights do? (Multi engine)
Coarsen pitch
49
Where does the MAP gauge read from?
Between the throttle valve and the cylinder inlet valve
50
What is the tendency of the centrifugal twisting moment?
To fine the propeller
51
What is the tendency of the aerodynamic twisting moment?
Coarsen the propeller
52
When increasing power… (CSU)
Increase RPM
Increase MAP
53
When reducing power (CSU)
Reduce MAP
Reduce RPM
54
How do you avoid detonation in a supercharged engine?
Use only approved power settings
Use correct leaning procedures
55
Which valve is usually smaller?
Inlet valve
56
What rate does the camshaft rotate?
Half crankshaft speed
57
What is valve lead?
Intake valve opening just before piston reaches TDC
58
What is valve lag?
Intake valve closes just after the piston reaches BDC
59
What is compression ratio?
Volume of cylinder with piston at BDC/volume of cylinder with piston at TDC
60
What are the consequences of an over rich mixture?
Reduced power
Rough running
High fuel consumption
Fouling of spark plugs
61
What are the consequences of an overlean mixture
High CHT
Detonation
62
What does octane rating refer to?
The resistance of the fuel to detonation
63
What are some possible causes of detonation?
Overlean mixture
Unnecessarily high power settings
Excessive MAP with low RPM
Incorrect or time expired fuel
64
What are some fuel tank types?
Wet wing
Rigid removable
Bladder
65
What does the ignition harness do?
Carries the current from the magneto to the spark plugs
66
What are some functions of the oil system?
Lubrication
Cooling
Cleaning
Lengthening engine life
Providing a seal between cylinder walls, pistons and rings
Providing oil for variable pitch propeller system
67
What are oil types?
Ashless dispersant oil
Mineral oil
Synthetic oil
68
What are the benefits of a dry sump?
Prevention of oil starvation with high g
Increased oil capacity
Better oil temperature control
More power as the crankshaft doesn’t have resistance from oil splashing
69
Where is the oil pressure sensor?
Just after the oil pump
70
What are the benefits of even cylinder distribution of fuel?
Each cylinder produces the same amount of power
Smoother running
Easier starting
Less chance of detonation
Better power output
71
Disadvantages of fuel injection systems
More complex and expensive than float carburettors
More susceptible to fuel contamination due to fine fuel lines
More prone to fuel vaporisation
Vapour locks can make hot starts difficult
72
What are the main components of a supercharger?
Impeller
Diffuser
Compressor
73
What happens when a wastegate is fully open?
All exhaust gas is directed away from the turbine and the engine functions as if it were normally aspirated
74
What happens when a wastegate is fully closed?
All exhaust gas is directed over the turbine, creating a maximum amount of compression of the incoming air
75
What is full throttle height in a supercharged engine?
The altitude at which the rated boost is available at a certain RPM
76
What is a supercharged engine critical altitude?
The highest altitude at which maximum rated power can be obtained with full throttle
77
What happens above the critical altitude of a supercharged engine?
Reduction in MAP and power output
78
What is the name of the spring in a CSU?
Speeder spring
79
What happens in a failure of the speeder spring?
No resistance for the flyweights and will cause the governor to sense an overspeed condition which will drive the blades to the coarse pitch stops
80
Advantages of hydraulic systems
Large amounts of power can be transmitted using relatively small components
Power can be multiplied even without the use of a hydraulic pump
Hydraulic lines can be easily routed through inaccessible parts of the aircraft
81
Disadvantages of hydraulic systems?
System integrity is required for it to work
Loss of fluid can have serious implications such as fire, loss of control, loss of system
Weight, components and fluid can be heavy
82
What are the two types of hydraulic system?
Active
Passive
83
What should the properties of a hydraulic fluid be?
Non compressible
Thermally stable
Fire resistant
Non corrosive to its systems
84
Purpose of a hydraulic reservoir
Provides a reserve of fluid
Allows for variation in fluid volume
Allows for expansion of fluid due to temperature
Provides a head of pressure to prevent cavitation at the engine driven pump
85
Two types of hydraulic lines?
Pressure line - carries fluid under pressure
Return line - returns fluid to the reservoir
86
What are the functions of the hydraulic accumulator?
Help the pump maintain pressure when the system demand is high
Provide a limited emergency pressure supply if the pump fails
Smooth out pressure fluctuation and surges and so reduce vibration and noise
87
What are some possible hydraulic system faults?
Air in the system
Fluid leakage
Low accumulator pressure
88
What can air in the hydraulic system cause?
Pump may overheat due to inadequate cooling and lubrication
Air may also allow for compression reducing the power the fluid can generate
89
What can hydraulic fluid leakage cause?
An actuating piston which has just moved forward may move back again as the oil that drove it forward escapes
90
What are the effects of low hydraulic accumulator pressure?
The pump does more of the work resulting in slower operation of the system
Reduction in the emergency supply of fluid if the pump fails
May cause noisy operation and vibration
91
What are the two main types of gear shock absorbers?
Spring steel struts
Oleo pneumatic struts
92
What does the nose gear consist of?
Oleo pneumatic strut
Shimmy damper
Torque link
93
What does the torque link do?
Fitted to an oleo to prevent it turning left or right of its own accord
94
What are the two types of retractable undercarriage?
Hydraulic
Mechanical
95
What are the three common types of fire detectors?
Overheat - thermal switch
Rate of temperature rise - thermocouple
Flame detector - optical
96
What are the four types of fire extinguishers?
Water
Dry chemical
Carbon dioxide
BCF
97
What barometer is in an altimeter?
Aneroid barometer
98
How does the air enter a VSI?
Capsule is directly from the static vent
Instrument case via a choke
99
How does an ASI measure indicated airspeed?
Taking the total pressure entering the pitot tube and subtracting the static pressure
100
What happens to the altimeter with a blocked static vent
Indicates the altitude at which the blockage occurred
101
What happens to the VSI with a blocked static vent?
It will read zero
102
What effect does a blocked static vent have on the ASI?
Under read in a climb
Over read in a descent
103
What instruments will a blocked pitot tube affect?
ASI
104
What is the effect of a blocked pitot tube on the ASI?
Over read in a climb
Under read in a descent
105
What is PUD SUC?
Pitot blocked - ASI
Underread
Descent
Static blocked - ASI
Underread
Climb
106
What causes VSI lag?
The restricting diffuser in the pressure case slows the equalisation process of air pressure between the outside atmosphere and that of the instrument pressure case
107
What instruments are effected by alternate static source?
ASI and altimeter tend to overread
108
What are the two main properties of gyroscopes?
Rigidity
Precession
109
What is a space gyro?
Mounted in gimbals
Can be isolated from movement in roll, pitch and yaw
110
Main advantage of electrically driven gyros?
Faster speed providing greater rigidity and a more stable reference platform
111
The AH uses which gyroscopic property?
Rigidity
112
What property does the turn and balance rely on?
Precession
113
What errors does the AH show when the aircraft is accelerated?
Roll effect - false right wing low
Pendulous vanes precess into false climb
114
What is real wander?
DG drifting out of alignment due to friction and small imbalances. Also called mechanical drift
115
What are the compass acceleration errors?
South
Accelerating
North
Decelerating
116
What is the main purpose of fuel vents?
To avoid fuel starvation
117
An aircraft fitted with a constant speed propeller, what effect will reducing airspeed have on propeller pitch and RPM?
Propeller pitch becomes fine
RPM remains constant
