FACTS Flashcards
1
Q
What are the various airspeeds and their corrections?
A
— draw diagram —
2
Q
Formula for dynamic pressure?
A
1/2 ρ V²
3
Q
What is soft iron?
A
iron that becomes saturated easily and loses its magnetism easily
4
Q
What is hard iron?
A
iron that is difficult to magnetise that keeps its magnetism
5
Q
When do acceleration errors occur in relation to the magnetic compass?
A
When going E or W
6
Q
What is a three axis data generator?
A
an artificial horizon gyro and a remote indicating compass all together in box
7
Q
How many degrees of freedom does a Directional Indicator have?
A
2
8
Q
What kind of spin axis does a Directional Indicator have?
A
Horizontal
9
Q
What is DI Error?
A
Real Wander + Earth’s Rotation + Latitude Nut + Transport Wander
10
Q
What are the signs for the different DI errors?
A
11
Q
Formula for Transport wander?
A
Transport wander (°) = change of longitude x Sine (mean latitude)
12
Q
Formula for Earth’s rotation
A
15 x Sin (Latitude) [degrees per hour]
13
Q
What does a laser gyro measure?
A
Rotation
14
Q
In the gyromagnetic compass , where does the signal feeding the precession amplifier come from?
A
the error detector
15
Q
What causes gimballing errors?
A
banking the aircraft
16
Q
what are the pressure conversion factors?
A
1lb/in² = 2 in Hg
1 in Hg = 3386.39 Pa
1 Bar = 100 000 Pa
1lb/in² = 0.0689 Ba
17
Q
What are the elastic pressure sensing elements in increasing order of pressure sensed?
A
Diaphragms Aneroid capsule Pressure capsule Bellows Bourdon Tubes
18
Q
What are diaphragms typically used for?
A
sense the difference between cabin pressure and atmospheric pressue
19
Q
What are the two types of bellows?
A
Aneroid and Pressure
20
Q
What is a bellow made up of ?
A
Capsules
21
Q
What might an aneroid bellow be used for?
A
Measure / sense the intake pressure of a gas turbine in order to control the fuel flow via and FCU or a FADEC
22
Q
What shape is a Bourdon tube?
A
Curved like a C
23
Q
What kinds of pressure are Bourdon tubes used to measure?
A
High and low, typically high
24
Q
Example of Bourdon tube pressure measurement?
A
Engine oil pressure
25
What is the purpose of a damping choke on the Bourdon tube?
To prevent significant loss of oil in case the the indicator were to leak
26
What is a manifold absolute pressure gauge (MAP) for?
indicates the absolute pressure in the intake manifold of a piston engine
27
What is MAP and indication of?
Engine power
28
What is the upper limit of MAP on a normally aspirated engine?
atmospheric pressure
29
Where can a MAP greater than atmospheric be created?
In a supercharged engine (which pressurises the fuel/air mix)
30
Why might a MAP indicate atmospheric while the engine is running?
leak in the pressure gauge line
31
What is the formula relating torque and RPM
Torque x RPM = power
32
What does epicycloidal mean?
sun and planet gears
33
What are the two ways in which Torque can be measured?
1) By measuring the oil pressure at the fixed crown of a reducer gear on an epicycloidal main engine gearbox
2) By measuring change in phase between the torque shaft and the reference shaft
34
Popular system for measuring moderate temperatures?
nickel wire coil
35
What are nickel coil wire systems typically used for ?
OAT or cabin temperature
36
What kind of arrangement is used for sensing moderate temperatures?
Wheatstone bridge in conjunction with a ratiometer
37
What is an example of a self powered temperature gauge?
bi-metallic strip
38
What is a common use for a bi-metallic strip?
- Operating temperature sensitive switches
| - overheat detection systems
39
In a piston engine what is used for monitoring engine condition?
Cylinder head temperature (CHT)
40
What is exhaust head temperature used for in a piston engine?
- mixture control
| - performance
41
What temperature is measured in a gas turbine engine?
gas temperature
42
Where are TGT and EGT measured?
The outlet of the high pressure turbine
43
What is the range of temperatures sense in the outlet of the high pressure turbine?
700°C to 1000°C
44
What is used to measure gas temperature in a gas turbine engine?
a thermocouple
45
What is the principle of a thermocouple?
Dissimilar metals can create an electrical potential which is proportional to the temperature.
46
What is the name of the instrument used to detect very small changes in temperature in a thermocouple?
millivoltmeter or galvanometer
47
Where are the junctions of a thermocouple located?
Cold junction in the cockpit and hot junction in the gas pipe
48
Does a thermocouple require an external power source?
No
49
What is used for very high temperatures?
A radiation pyrometer
50
Formula for thermocouple?
E = K x Th
```
E= EMF
Th = hot junction temperature
K = constant
```
51
Formula for SAT?
SAT = TAT / ( 1 + K 0.2M²)
52
Formula for TAT?
TAT = SAT * ( 1 + 0.2M²)
53
What does float type fuel gauges require?
DC power supply
54
What is the formula for capacitance?
C = E x A / D
```
E = the dielectric permittivity
A = area of the plates
D = distance between the plates
```
55
What is the formula for the charge?
Q = C x V
```
Q = charge in coloumbs
C = capacitance in farads
V = voltage in volts
```
56
What is the relative capacitance of fuel compared to air?
fuel has twice the capacitance of air
57
What are primitive fuel flow indicators based on?
Venturi
58
What are the two systems for mass flow indicators?
Stator torque or rotor torque
59
What is used to measure rotational speed?
tachometer
60
Maximum practical length of drive on mechanical tachometer?
2m
61
What does a yellow or red section indicate on a RPM meter?
high prop vibration
62
Does a tachogenerator require an electrical supply?
NO
63
What is the advantage of the electric tachogenerator over the mechanical generator?
allows engines to be placed further away from the cockpit
64
What is a disadvantage of the DC electrical tachometer?
requires a commutator and carbon brushes, leads to wear and electrical sparking which can cause radio interference.
resistance causes voltage loss in transmission, which can cause an indication error
65
What happens to the out put of a single phase AC tachogenerator?
it gets rectified to DC
66
Which instrument uses a squirrel cage motor?
a 3 phase electrical tachogenerator
67
What is the principle of operation in the three-phase electrical tachometer?
Changes of frequency indicate RPM
68
What does a three-phase electrical tachometer consist of?
a three-phase generator, a synchronous motor and a magnetic tachometer
69
What is the advantage of the three phase electrical tachometer?
phase is sensed instead of voltage so voltage loss in transmission is not a problem
70
What is a potential disadvantage of the three-phase electrical tachometer?
wiring (if there is one!)
71
What is the idea behind the electronic tachometer?
senses RPM without and direct contact with the engine
uses a probe with an electromagnet to detect passage of notched teeth
72
How might the electronic tachometer be referred to?
Phonic wheel
Inductive probe tachometer
73
what is the synchroscope use for?
balance the RPM of a multi engine turboprop
74
What causes damage during vibration?
positive and negative acceleration
75
What does the vibration indicator indicate
the vibration amplitude at a particular frequency
76
What happens to the vibration signal before it is transmitted to the vibration indicator?
it is filtered (for unwanted frequencies) and amplified
77
What are N1 and N2 in a typical modern high-bypass engine?
```
N1 = low speed or fan RPM
N2 = high-speed shaft RPM
```
78
How is thrust measured?
by the acceleration of a MASS of air
79
What is EPR?
EPR = turbine outlet pressure/compressor inlet pressure
80
What are the sensors used for thrust pressures?
either electro-mechanical based on bellows or electronic transmitters which use transducers
81
What happens if the compressor inlet sensor is blocked for take-off
EPR gauge would over read and insufficient thrust for take off would be set
82
What should the take-off EPR be crosschecked against?
N1 (alternative less accurate measurement of thrust)
83
In a capacity gauging system what is it that causes the effects on volume of fuel of temperature changes to be eliminated?
Because the dialetric constant varies directly with density
84
What does FADEC use as a primary thrust measurement ?
EPR and maybe N1 as a fallback
85
What is the measuring element of a manifold pressure gauge (MAP)?
- 2 bellows joined together;
- 1 aneroid
- 1 pressure
86
What is a dielectric?
an insulating material
87
What is capacitance measured in?
farads
88
What can fuel flow be used for?
to monitor the performance of a jet engine - fuel flow integrated over time can be compared with the quantity from the fuel gauging system
89
What does a venturi flow indicator work?
reduced pressure in the venturi compatred to the normal pressure in the pipe in an indiction of flow rate
90
What kind of sensor does the venturi flow indicator use?
a capsule
91
How does the variable orifice flow indicator work?
vane displacement converted into electrical signal and fed to instrument
92
Turbine volume flow indicators how?
blades of the turbine are build with magnetic inserts, as the turbine rotates blades pass an induction coil in the casing
93
What is a disadvantage of a turbine volume flow indicator?
does not cope well with large flow rate and temperature changes
94
What is the principle of the mass flow indicator?
displace fuel so that it swirls in pipes and then sense angular momentum.
angular momentum is a product of rotational speed and mass
95
What is the idea with Stator Torque mass flowmeter?
Impeller turned at constant speed. A Stator (turbine mounted to a spring) take the twirl out of the fuel. The greater the angular momentum the more twisting force on the stator as it does this.
96
What is the principle of the rotor torque mass flow meter?
- impeller turned at fixed RPM.
- motor lags behind rotor, spring is twisted
- magnetic inserts create pulses in inductive pickups
- time interval between pulses indicates the amount of twist on the spring and hence the mass flow
97
What is the name for a system where fuel flow is integrated over a period of time and this is combined with the fuel flow indication?
Integrated flowmeter system
98
what are two types of vibration sensors used?
Piezoelectric crystals or magnets.
99
What do you need to make the compressibility correction from EAS to CAS?
pressure altitude
100
What is position error?
error caused by airflow of the sensor being disturbed by the aircraft structure
101
what is configuration error?
caused by changes in airflow over the sensor as flaps, slats or gear are selected
102
what is manoeuvre error?
error caused by manoeuvre such as sideslips
103
What is hysteresis error?
the reluctance of a capsule to change its shape after a period at one altitude
104
What is the construction of the Machmeter?
a airspeed indicator and an altimeter in the same case
105
What are the formulae for Mach Number?
M = TAS / LSS
AND
M = (Pitot - Static) / Static
106
What is the formula for IAS?
IAS = Pitot - Static
107
When is CAS = TAS & CAS = EAS?
at standard sea level conditions
108
What defines the density correction applied to EAS?
pressure altitude and temperature
109
What are the two sub categories of position error?
configuration error and manoeuvre error
110
what is the difference between pressure error and position error?
nothing - they both refer to the same thing
111
mach number can be through of as a measure of what?
compressibility
112
what is the difference between pressure altitude and true altitude?
pressure altitude is not affected by temperature
113
What is VMO
Maximum operating limit in knots
114
What does the Striped needle on the airspeed indicator indicate?
VMO
115
What causes pressure error to vary?
speed of the aircraft
116
what causes the position error of an altimeter to vary?
speed of the aircraft; position error increases with speed,
position error is due to the disrupted airflow over the pressure sensors
117
What is VNO?
Maximum Normal Operating Speed
118
Considerind the ASI what is the green scale for ?
clear aircraft configuration
119
Considering the ASI what is the white scale for?
landing configuration
120
What is the St. Verant formula used for?
used with CAS to derive EAS
121
What can be said about the compressibility error correction from CAS to EAS?
It is always negative and depends only on Mach number
122
What is the purpose of the vibrating device in an altimeter?
reduce the friction of the linkages
123
What are the inputs of the ADC
Static Pressure, Total Pressure, TAT
124
What is Vy?
Best single engine rate of climb speed
125
What are the main inputs to an air data computer?
- TAT
- Static Pressure
- Total Pressure
- (Angle of Attack) - peripheral input
126
In the case of the remote indicating compass when will the rotor coil have a current induced in it?
It will have a current induced unless it is at 90° to the resultant field by which it is surrounded.
127
What type of gyro is used in a remote indicating compass?
a tied gyro with two gimbals and therefore 2 degrees of freedom, controlled in topple and drift.
128
Summarise acceleration/deceleration errors in Northern and Southern hemispheres
E/W Acceleration: turn towards near pole
| E/W Deceleration: turn towards far pole
129
What is the aclinic line?
line of no magnetic dip
130
When are turning errors maximum?
Turning through North or South
131
When are turning errors zero?
Turning through East & West
132
Where would turning errors be worst?
Turning errors are function of dip so will be worst at the poles
133
Where would turning errors be least?
Turning errors are a function of dip so will be least on the aclinic line
134
How do turning errors vary with bank angle?
Turning errors are a function of bank angle so with greater errors at greater bank angles
135
What is the effect of liquid swirl?
Lag (increases lag and decreases lead) in all cases
136
what is parallax error
error caused by reading something from the side, not looking at it directly
137
What is the purpose of a compass swing?
To remove deviation ( or to get it within the limits of the compass and record the residual deviation)
138
How is deviation compensated for?
By adjusting pairs of permanent magnets
139
Where is the flux density greatest in a magnet?
a short distance from the ends of the magnet
140
What are the standardised rates of turn?
Rate 1: 180° a minute
Rate 2: 360° a minute
Rate 3: 540° a minute
141
Where is the directive force of the earth's magnetic field greatest?
At the magnetic equator
142
What causes the quadrantal deviation of the magnetic compass?
the soft iron pieces influenced by the geomagnetic field
143
Considering the artificial horizon, what happens when a aircraft decelerates on landing?
False nose down indication and bank to the left
144
A DI has which kind of spin axis?
horizontal
145
A DI has how many degrees of freedom?
2
146
A DI has how many degrees of freedom?
2
147
Describe the artificial Horizon Pitching and Bank errors
---
148
What is an out of balance yawing force into the turn called?
Slip
149
What is an out of balance yawing force out of the turn called?
Slip
150
What is yaw?
movement of the aircraft around its own vertical axis
151
What is turn?
turn is the movement of the aircraft about the earth vertical axis and will result in a change of heading
152
How is the direction or rotation chosen in a turn indicator?
So that when the aircraft banks into a balanced turn the gyro precesses in the opposite roll sense to keep its axis more or less horizontal and therefore keep it more sensitive to turn rate
153
What will the reading of a turn indicator be if the electrical supple fails?
Zero as the gyro will stop. Any leaks or reductions in voltage tend to make the turn indicator under read.
154
What errors is the slip indicator subject to?
None
155
What is the formula for Angle of bank?
Angle of bank = ( TAS / 10 ) + 7
156
What is the formula for the radius of the turn in NM?
Radius of turn = TAS / ( Rate of turn * 60 pie )
157
How does a Turn Co-ordinator differ from a turn indicator?
- Gimbal is raised at the font by 30°
| - sensitive to both roll and yaw
158
What turns to turn co-ordinators indicate accurately?
Rate one turns
159
How will acceleration affect the artificial horizon?
Nose up attitude
160
How will deceleration affect the artificial horizon?
Nose down attitude
161
What is gimbal error associated with?
Banking the aircraft
162
How many degrees of freedom in a 3 axis data generator?
2
163
What spin axis does a 3-axis data generator have
VERTICAL
164
Why are air driven artificial horizons made pendulous?
To reduce erection time on startup
165
How is the artifical horizon's spin axis tied to the earth vertical?
By a system of pendulous vanes and air jets that make the gyro precess back to the vertical if it is displaced
166
what are the advantages of the electrically driven AH?
- more rigid. squirrel cage motor drives twice as fast
- erection system can be made very fast
- turn and accelerations errors minimised to eliminated
167
How does the electrically driven AH detect displacement of the spin axis?
Mercury tilt switches
168
What can an electronic AH do in a turn?
Cut out the erection system
169
what sign does apparent drift have in the Northern Hemisphere?
Right/Clockwise ---> Heading reduces ---> Negative Sign
170
What is an EARTH gyro?
Spin axis is tied by EARTH's gravity to remain in the EARTH VERTICAL
171
What is wander?
- movement of spin axis away from initial direction
| - DRIFT OR TOPPLE
172
Which flights are affected by transport wander?
Flights that go East or West
173
When does gimbal error occur in the DI?
when banking ( gimbals are not in line)
174
What is measured in order to display rate of turn?
Yaw
175
How is the gyro of a gyromagentic compass in azimuth?
a TORQUE motor
176
In a remote indicating compass what feeds the torque motor?
the precession amplifier
177
How many gyros are in an AHRS (attitude and heading reference system)?
3
178
What does Latitude nut account for?
Earth rotation
179
What information can the INS provide?
- Position
- Track
- Heading
- GS
- Height
180
What does a high cost index mean when entered into the FMS?
High airspeed and high fuel consuption
181
What does cost index 0 result in in the FMS?
maximum RANGE airspeed
182
What is the primary purpose of the autopilot?
reduce pilot workload
183
Define autopilots based on their axes?
Single axis: roll
Two Axis: pitch& roll
Thee Axis pitch, roll & yaw
184
What are the basic functions of the autopilot?
pitch and roll attitude hold
185
What are the operating modes of a full 3 axis autopilot?
- heading, altitude and vertical speed capture and hold
- IAS ot MACH hold
- Coupling to VOR track and to ILS Localiser and glidepath
- Coupling to FMS horizontal and vertical profiles
- Autoland
186
What operations can not be carried ot without autopilot?
- CAT II & CAT III approaches
- ETOPS
- Reduced Vertical Separation Minima
187
What is the function of the outer loop in an autopilot system?
Control the inner loop to stabalise
188
In an autopilot what is used to control the speed in the
| climb?
Pitch control
189
In an autopilot what is used to control the speed in the glide path and altitude hold modes?
the autothrottle
190
Which look is used to controls stablity?
inner loop
191
With mach tuck where does the centre of pressure move?
rearwards
192
When does Mach trim system operate?
At high mach numbers e.g 0.7 - 1.0
193
What does mach trim change?
the horizontal stabilizer
194
What are the EUROCAE software failure levels?
Level A - Catastrophic
Level B - Hazardous
Level C - Major
Level D - Minor
Level E - No effect
195
The flight data recorders must preserve the conversation and aural warnings of the last :
30mins
196
flight data recording system must be able to store the recorded data for a minimum of the last
25 hours
197
How is a TCAS II resolution advisory represented?
a red square
198
What audio warning doesTCAS II provide?
"climb" "descend"
199
How is a traffic advisory represented in TCAS II
Solid amber circle
200
In radio altimeter what is the height measurement based on?
A frequency modulation wave between 4200-4400MHz, for which the frequency difference between the transmitted wave and the received wave after ground reflection indicates true height.
201
What is the maximum range of the radio altimeter
0-2500ft
202
The solid white or cyan diamond denotes ?
The solid white or cyan diamond denotes traffic inside 6nm and 1200ft OR inside 6nm with no altitude data. In this example we have altitude data.
203
What signals to radio altimeters use?
use continuous wave (CW) NOT pulsed signals and have an operating frequency range between 4200MHz and 4400MHz. (SHF)
204
GMWS Minimum operating range?
50' - 2500'
205
The radio altimeter uses which wavelengths?
4200-4400MHz is a Super High Frequency and is Centimetric in length.
206
When is the stall warning required?
The higher of 5KT CAS above the level flight stalling speed or 105% of the level flight stalling speed for the aircraft configuration at the time
207
When is a take off warning created?
if the aircraft is not in the correct configuration for take off; incorrect flap or trim setting (stabiliser not in the correct position), parking brake on
208
What frequency band does the radio altimeter use?
SHF or Centimetric
209
What radio band does the radio altimeter use?
4200-4400MHz
210
How many antenna does a radio altimeter use?
2 - one for transmission and one for reception
211
What are the inputs to the GPWS
The inputs to GPWS are easily recalled by the mnemonic 'Royal Air Force Navigator'
R - radio altimeter
A - air data computer (includes vertical speed and pressure altitude)
F - flaps/gear (configuration)
N - Nav receiver (ILS glideslope deviation)
212
GPWS height span?
2,500' - 50'
213
What are the TCAS inputs
The TCAS computer receives inputs from: Transponders (Pressure Altitude from mode C), Rad alt (Prevents an RA below 1000') and a/c configuration (flaps/gear).
214
What is the use of the Radio altimeter in TCAS II?
The Rad alt input to TCAS gradually inhibits RA's until at 1000' and below RA's are prevented.
215
Your TCAS determines the bearing of the intruding aircraft by:
TCAS II uses a directional antenna to determine the relative bearing of an intruder.
216
What is currently the best air to ground radio system to use when flying over the North pole?
HF
217
What frequencies can Datalink communications can use?
Datalink communications can use: SATCOM, HF COM or VHF COM. Satcom is the fastest data transmission, then VHF, and lastly HF.
218
What is CPDLC?
CPDLC is a Pilot/ATC data link.
219
What is the nature of CPDLS communications?
If the communication is regarding the piloting of the a/c, then it will be a CPDLC .
220
What kind of pressure does an aneroid capsule measure?
absolute pressure.
