Flight Data Sensors and Miscellaneous Components Flashcards
1
Q
What can a layer of ice do to the aerodynamic characteristics of aircraft?
A
- Can reduce lift by 30%
- Increase drag by 40%
2
Q
What can ice mean to the conditions for aerodynamic stall?
A
A/C may enter a stall before the stall warning activates
3
Q
What are anti-icing systems?
A
Systems used to prevent the build up of ice on essential components and lifting surfaces, acting prior to entering icing conditions.
4
Q
What are some forms of anti-icing systems?
A
- Pitot-static
- Angle of attack vanes
- Windscreens
- Engine intakes and engine components
- Wing and empennage leading edge surfaces
- Propeller
- Radome
Can be pneumatic, electrical or chemical
5
Q
What are some forms of de-icing systems?
A
- De-icing systems are only activated after ice accretion has occurred.
- This is more energy efficient
- De-icing can be electrical, pneumatic, chemical, or mechanical.
6
Q
What are some methods to determine icing conditions?
A
- Standing Instructions
- Aircraft Flight Manual
- Visual Detection
- Automatic detection (when icing conditions are encountered, A/C will prompt an alert)
7
Q
Is the PC-21 approved for flight into icing conditions?
A
No
8
Q
What are two thermal anti-icing de-icing systems?
A
- Bleed Air from Hot Compressor
2. Electrical Heaters
9
Q
What are some common A/C components that use bleed air as anti-icing?
A
- Engine
2. A/C leading edge
10
Q
What are some common A/C components that use electrical heating as anti-icing?
A
- Pitot probes
2. AOA probes
11
Q
What are ground based spray equipment used for?
A
- Melt any ice and snow build up (de-ice) on the ground
2. Prevent the ice from re-forming until the aircraft is airborne (anti-ice)
12
Q
What are some methods used to prevent windscreen anti-ice/de-ice?
A
1) Electrical heated windscreens that
Provide both anti-ice and de-ice
and Provide inner windscreen fog protection
2) Fluid systems such as rain repellent or chemical de-ice systems
3) Mechanical through rubber windscreen wipers
13
Q
What are pneumatic windscreen systems used for?
A
Rain removal
14
Q
What do the Air Speed Indicator (ASI), Vertical Speed Indicator (VSI) and Altimeter rely on?
A
- Air pressure in the atmosphere
- Change in air pressure is important as well
15
Q
What are the ASI, VSI and Altimeter calibrated against?
A
ISA Conditions
16
Q
What are ISA conditions?
A
T = 15 C P = 1013.25 hPa rho = 1.225 kg/m^3 ELR = -2/1000 ft -56.5 C @ 36,000 ft
17
Q
What is static pressure?
A
Exerts equally in all directions, decreasing as altitude increases.
18
Q
What is dynamic pressure? What factors determine it?
A
- Dynamic pressure is felt as relative movement between a body and the surrounding air.
- Air density and velocity
19
Q
What is pitot pressure?
A
Static pressure + Dynamic pressure
20
Q
How does a pressure altimeter work? How are they calibrated?
A
- Uses static ports on the A/C to determine aircraft height
- Changing static pressure will expand and contract aneroid barometers.
- Calibrated to ISA conditions
21
Q
What are QNH and QFE? How can the pilot change the altimeter to be calibrated for these values?
A
- QNH = Actual sea level pressure
- QFE = Airfield level pressure
22
Q
What is the PITHBLOT acronym used for? What are the letters stand for?
A
Altimeter errors:
- Position error
- Instrument error
- Temperature error
- Hysteresis error
- Barometric error
- Lag error
- Orographic effect
- Transonic jump
23
Q
What are used as compensation devices to correct these errors?
A
Air Data Reference Units
24
Q
What is position error?
A
Static source outside the A/C effected by airspeed configuration, sideslip or balance, power, steep turn, angle of attack
25
What is instrument error?
Caused by manufacturing tolerances
26
What is temperature error?
- Occurs when atmospheric conditions differ from the standard atmosphere calibration.
- In cold air masses, some corrections sometimes have to be made
27
What is hysteresis?
- An error associated with the imperfections of the aneroid capsule
- Friction or elasticity
28
What are barometric errors?
Errors caused by the difference between actual pressure and that to which the altimeter has been set
29
What are lag errors?
Errors due to the time it takes for mechanical devices to react to changes in pressure.
30
What are orographic errors?
Occurs when a current of air meets a hill or mountain.
31
What is a transonic jump?
Shockwaves momentarily increase static pressure during transonic flight.
32
What is typically regard as the most significant altimetry error?
Mis-setting of the correct barometric reference by the pilot.
33
What are regarded as the most significant instrument errors?
Temperature and barometric
34
How does the Airspeed Indicator (ASI) determine air speed?
Uses an aneroid capsule or diaphragm to measure the difference between static pressure and pitot pressure to determine dynamic pressure, which is proportional to the airspeed.
35
What causes some ASI errors?
- Density error - when density is not at ISA mean sea level
- Compressibility error - varies with speed and altitude, causes airspeed indicator to overread
- Position error (Pressure error) - Cause by changes in static pressure around the aircraft due to its movement through the air
- Instrument errors - caused by manufacturing tolerances
- Blockages in pitot or static ports
- Leaks in pitot or static ports
36
What does a VSI measure? How does it do it?
- Vertical Speed Indicator (Rate or descent/ascent per minute)
- Instrument contains a diaphragm or capsule inside a case
- When static pressure changes, the diaphragm or capsule moves immediately when a change in static pressure is detected while the pressure in the case lags.
- This difference results in the indication of vertical speed
37
What are the errors associated with VSI?
```
P = Position error
I = Instrument error
L = Lag
T = Transonic jump
Blockages
```
38
What is an Air Data Computer (ADC)?
Single computer system that can process pitot and static information and display them with a higher degree of accuracy.
39
What types of measurements does the ADC use to compensate for instrument errors?
- Temperature
- Angle of attack
- Aircraft Configuration
- Side slip angle
40
What forms of redundancy are displayed by the ADC?
- Multiple probes and ports provide information
- ADC monitors integrity of the probes and ports
- Standby instruments that can be used directly if the ADC fails
41
What are the main advantages of the Air Data Computer?
1. Complexity is avoided
2. Instrument error can be corrected more accurately
3. Reduced display lag
4. Flexibility in the method of presentation
5. Easier and quicker maintenance
42
What are some disadvantages of the Air Data Computer?
1. Requires electrical power
2. If there is a fault, it can result in nuisance information displayed to the pilots
3. Undesirable control inputs for autopilots
43
What is a Direct Indicating Compass (DIC) also known as?
Standby compass
44
What are the following properties that direct indicating compasses must exhibit?
1) Sensitivity :
- Achieved by increased the magnetic moment by increasing size of the magnet (must be done within reason otherwise will cause large overshoot continuously)
- Reducing friction around the pivot point
2) Horizontality
- A pendulum system can counteract the vertical element of movement as compass moves away from the equator
3) Aperiodicity
- Vibrations and oscillations experienced in flight tend to cause undesirable oscillations of the magnet system.
- This is achieved by using magnets with high magnetic moment and low moment of inertia AND damping filaments
45
What are the main errors associated with a Direct Indicating Compass (DIC)?
1) Parallax Error - Error that occurs when it is viewed from an angle
2) Liquid Swirl - When A/C rolls out of a turn, the liquid in the swirl continues to move, resulting in overshoot.
3) Scale Error - Slight imperfection in the manufacturing of the compass
4) Alignment error - Compass becomes misaligned with the longitudinal axis of the A/C
5) Deviation - When the DIC experiences interference from other A/C components magnetic fields such as electrical fields from radios, electronics, magnetized parts and the engine.
46
What is acceleration error?
- As a result of the vertical component to earth's magnetic field further away from the equator, the magnet's pivot point and center of gravity will become misaligned, called COMPASS DIP
- When the A/C accelerates/ decelerates, the compass will swing
47
What acronym is used to remember directions of acceleration error in the southern hemisphere? When is it most pronounced?
SAND
- South turn when Accelerating
- North turn when Decelerating
Most pronounced when flying East to West
48
What is turning error? What acronym is used to remember it? When is the effect most pronounced?
- Caused by the same compass dip that causes acceleration errors
- ONUS = Overshoot North Undershoot South
- Most pronounced turning through North and South
49
What is a compass swing?
- Procedure for making adjustments and calibrations to compensate for some of the interferences in compass dip and others
50
What is a deviation card?
Once the compass has been corrected, there will still be some errors and these are shown on the deviation card in the cockpit near the compass.
51
What are the different types of gyroscopes and where are they used?
1) Spinning Gyroscopes - Used in aircraft instruments
2) Optical Gyroscopes - Used in aircraft heading and attitude systems
3) Vibrating Gyroscopes - commonly used in drones, mobile phones and computer gaming consoles
52
What is a typical spinning gyroscope consist of?
- Rotor
- Inner frame (gimbal)
- Outer gimbal
- A frame
53
What other method is used classify gyros ?
Degrees of freedom
54
What are the fundamental mechanics that provide the basis of the laws of gyrodynamics?
- Moment of Inertia
- Angular moment
- Torque or rotational twisting moment
55
What is rigidity in space?
The resistance of a spinning rotor to displacement from its axis (tenacity to maintain its erect attitude).
56
What is the first law of gyrodynamics?
If a rotating body is mounted as to be completely free to move about any axis through the center of mass, its spin axis remains fixed in inertial space, however much the frame may be displaced.
57
How can best angular momentum and rigidity be achieved?
- Concentrating rotor mass as far as possible form the axis of spin, increasing the moment of inertia
- Increasing the rotational speed of the rotor
58
What is the second law of gyrodynamics?
- If a continuous torque is applied about an axis perpendicular to the spin axis, the spin axis will precess steadily until the direction of spin is the same as the direction of applied torque.
- The gyro will continue to precess until the torque is withdrawn
59
What is Rate of Precession?
The rate at which a gyroscope precesses is dependent upon the magnitude of the applied force and the rigidity of the gyro
60
What is the direction of precession?
Any torsional force applied to a gyroscope in other than the axis of rotation will act as if applied to the gyroscope 90 degrees in the direction of spin.
61
What are two different functions that gyros perform?
1) Rate gyros
| 2) Displacement gyros
62
What are rate gyros?
Only has one degree of freedom, and is used to measure rate of angular change, such as rate of turn.
63
What is a rate integrating gyroscope?
Designed for inertial navigation stable platforms.
64
What is a displacement gyroscope?
- Gyros with two degrees of freedom
| - Commonly used in heading reference equipment and older navigation systems and aircraft instruments
65
What are the three types of displacement gyroscopes?
- Space gyro
- Tied gyro
- Earth gyro
66
What is a space gyro?
- Has gyroscopic inertia with reference to a point in space.
- Unrestrained by any external force and free to drift and topple
- Used for Inertial Navigation Systems (INS)
67
What is a Tied Gyro?
- Two degrees of freedom gyroscope whose rotor spin axis is controlled or tied to a particular orientation by an external force.
- Horizontal place in gyroscopic compasses.
68
What is an earth gyro?
- A tied gyro shows orientation is maintained by the earth's gravity
- Used in instruments such as aircraft attitude indicators
69
What are the primary gyroscopic instruments?
1. Attitude Indicator
2. Heading Indicator
3. Rate of turn indicator
4. Remote indicating compass
70
What type of gyro does an attitude indicator use?
Earth gyro
71
What is wander relating to gyros?
Any departure of the gyro's spin axis away from its orientation.
72
What are the two types of wander ?
- Real: Caused by mechanical imperfections in a gyroscope.
| - Apparent: Caused by earth's rotation
73
What is gyroscopic drift?
Movement of the gyro spin axis in the horizontal plane
74
What is gyroscopic topple?
Movement of gyro spin axis in the vertical plane
75
What is apparent wander?
To an observer is will appear to wander as a result of the earth's rotation or due to movement of the gyro across the earth's surface
76
What is apparent drift?
Drift associated when the gyro is spinning horizontally to the earth's surface
77
What is apparent topple?
Movement of gyro spin axis in the vertical plane as a result of earth's rotation.
78
What is transport wander?
Occurs when a gyro is transported in an Easterly or Westerly direction across the earth at latitudes other that the equator.
79
What is gimbal lock?
Error that occurs when the gimbal rings of a gyroscope are moved in such a way that they align in the same plane, and gyroscope is turned in that plane.
80
What are gimbals relating to aircraft pitch attitude normally fitted with in order to prevent gimbal lock?
- Stops
| - Attitude will pitch to a limit and then turn about the roll axis until the pitch gimbal comes away from the stops.
81
What are the two main types of optical gyroscopes?
- Ring Laser Gyro (RLG)
| - Fibre Optic Gyro (FOG)
82
What are some applications of ring laser gyros?
- Aircraft Inertial Navigation
- Attitude reference systems
- Heading reference systems
83
What are vibrating gyroscopes used for?
Mobile phones, radio-controlled helicopter sand drones.
84
What is magnetic variation ?
Angular difference between True North (TN) and Magnetic North MN)
85
Does the FMS take into account magnetic variation? Can it be chosen not to?
Yes and yes
86
What are some factors that affect a radio waves ability to reflect back to transmitter?
- Aircraft surface (Metal vs wood)
- Coating on fuselages
- Shape (waves reflect much better from objects with sharp corners than with curves)
87
What is the doppler radar effect?
- Aircraft moving towards a transmitting radar will compress the return signal and send a higher frequency signal back to the receiver.
- Vice versa for aircraft moving away.
88
What is a continuous high-frequency wave?
- Continuous high frequency wave is transmitted and the return echo interrogated.
- Doppler principles allows the speed of the interrogated object be determined
- Range to target cannot be determined unless by periodically modulating the frequency
89
What is a pulse radar?
- Utilizes a single radar antenna.
- Sends out a single pulse before switching it over to receive the return signal
- Distance can be determined but speed cannot
90
What is a pulse doppler radar?
Group of high frequency signals is transmitted before the antenna is switched to receive mode.
91
What is a typical radar system?
1. Transmitter-receiver unit which sends and received high power radio frequency pulses
2. Duplexer which alternately switches the antenna from transmitter to receiver
3. Display which displays the transformed video signal
92
What is a Doppler navigation radar?
- Uses doppler effect to determine aircraft' ground speed and drift
- Narrow radar beam is transmitted forward and downwards from the aircraft at an angle of usually between 60 and 70 degrees
93
What is a ground mapping radar?
A component of an integrated navigation system used to present a picture of the ground in topographical form.
94
What is a sideways looking radar?
- Allows for a narrow pulse beam to be projected sideways and downwards from the aircraft.
- Used to produce a ground image which is stored for post flight analysis
95
What is an air intercept radar?
Used to detect and track aircraft at certain altitudes.
96
What is a weather radar?
Pulsed radar designed to detect the movement of moisture in the air, and by inference the degree of associated turbulence.
97
Do phenomenon such as clear air turbulence, dry microbursts, fog and small clouds display on weather radar?
Not typically!
98
What is a radar altimeter and how does it work? What is its accuracy?
- Sends pulsed signal to the ground and measures how long it takes to come back to the aircraft, thus determining altitude.
Accurate to +- 1.5 ft
99
What are the four major components of the radar altimeter?
1. Transmitter Chain
2. Receiver Chain
3. Range Computer
4. Indicator
100
What does the pilot have the ability to do with the radar altimeter?
Set a radar altitude for auto call out or altitude warning, depending on the operation and type of aircraft.
101
How frequently should an aircrafts compass be "swung"?
Once a year typically
