INS Flashcards
Errors of the DGI are:
Select one:
a. gimballing error, looping error, rolling error, rotor speed error, transport wander
b. gimballing error, random wander, apparent wander, rotor speed error, transport wander
c. acceleration error, turning error, altitude error, transport wander, rotor speed error
d. transport wander, apparent wander, latitude error, turning error, acceleration error
b. gimballing error, random wander, apparent wander, rotor speed error, transport wander
A directional gyro indicator is basically a:
Select one:
a. vertical axis earth gyro
b. vertical axis tied gyro
c. horizontal axis tied gyro
d. horizontal axis earth gyro
c. horizontal axis tied gyro
The maximum drift error sensed by an uncompensated DGI will be:
Select one:
a. 60° per hour
b. 45° per hour
c. 30° per hour
d. 15° per hour
d. 15° per hour
In an air driven directional gyro the air jets are attached to:
Select one:
a. the rotor axis
b. the instrument casing
c. the outer gimbal
d. the inner gimbal
c. the outer gimbal
Apparent wander may be corrected in a DGI by:
Select one:
a. correcting wander by means of air jets
b. attaching a bias weight to the inner gimbal which makes the gyro precess in azimuth in the same direction as apparent wander
c. causing the gyro to precess in a clockwise direction (in the Northern Hemisphere)
d. attaching a bias weight to the inner gimbal which makes the gyro precess in azimuth in the opposite direction to apparent wand
d. attaching a bias weight to the inner gimbal which makes the gyro precess in azimuth in the opposite direction to apparent wander
What type of gyroscope is fitted to a direction indicator?
Select one:
a. vertical axis & 2 degrees of freedom
b. horizontal axis & 2 degrees of freedom
c. vertical axis & 1 degree of freedom
d. horizontal axis & 1 degree of freedom
b. horizontal axis & 2 degrees of freedom
The latitude nut of a directional indicator (DI) is on the ………. gimbal and causes the gyroscope to precess around its ………. axis.
The correct words to complete the above sentence are:
Select one:
a. outer, horizontal
b. inner, vertical
c. inner, horizontal
d. outer, vertical
b. inner, vertical
In a DGI what error is caused by the easterly or westerly aircraft movement over the earth?
Select one:
a. real wander
b. Earth rate
c. transport wander
d. latitude error
c. transport wander
The spin axis of a directional gyro is maintained in ………. by means of ………. in an air driven gyro and by means of a ………. in an electrically driven gyro.
The correct words to complete the above sentence are:
Select one:
a. the yawing plane; air jets, wedge plate
b. the yawing plane; air jets, torque motor
c. the horizontal plane; air jets; wedge plate Incorrect
d. the vertical plane; air jets, torque motor
b. the yawing plane; air jets, torque motor
A directional gyro is valid only for a short period of time. The causes of this inaccuracy are:
- Earth rotation
- longitudinal accelerations
- a/c motion over the Earth
- mechanical defects
- gyro mass
The combination of correct statements is: Select one: a. all of them b. 1, 3 & 5 c. 1, 3 & 4 d. 1, 2 & 3
c. 1, 3 & 4
Does the DI (Directional Gyro Indicator) suffer from, Turning error and/or acceleration errors?
No
Total DGI error?
TD = Rw + Er + Ln + Tw
TW = easterly GS/60 x tan(lat) Er = -/+15 x sin(lat) LatNut = +/-15xsin(lat)
DGI
Drift due earth rate (ER) :
Northern hemisphere: -
Southernthern hemisphere: +
+/- 15 x sin(lat)
DGI
Drift due Latitude Nut (LN)
Northern hemisphere: +
Southernthern hemisphere: -
+/- 15 x sin(lat)
DGI
Drifte due Transport wander (TW) EAST:
Northern hemisphere: +
Southernthern hemisphere: -
TW = easterly GS/60 x tan(lat)
DGI
Drifte due Transport wander (TW) WEST:
Northern hemisphere: -
Southernthern hemisphere: +
TW = easterly GS/60 x tan(lat)
Acceleration during the take-off run causes the air driven artificial horizon to falsely indicate:
Select one:
a. the right wing going down due to pendulosity of the outer gimbal
b. the nose pitching up due to the action of the pendulous vanes
c. the right wing going down due to the action of the pendulous vanes
d. the nose pitching up due to pendulosity of the gyro housing
b. the nose pitching up due to the action of the pendulous vanes
When accelerating the electric artificial horizon:
Select one:
a. has a reduced roll error due to the pitch cut-out switch
b. has a reduced pitch error due to the roll cut-out switch
c. has a reduced pitch error due to the pitch cut-out switch
d. has a reduced roll error due to the roll cut-out switch
c. has a reduced pitch error due to the pitch cut-out switch
When turning through 90° at constant attitude and bank, a classic artificial horizon indicates:
Select one:
a. nose up and correct angle of bank
b. attitude and bank angle are correct
c. nose up and bank angle too high
d. nose up and bank angle too low
d. nose up and bank angle too low
An electrical artificial horizon employs ………. and ……….. to maintain its position in relation to ………..
Select the line of phrases given below that would complete the above statement correctly:
Select one:
a. mercury switches, torque motors, the local vertical
b. fast erect buttons, micro switches, local longitude
c. a precession circuit, a torque motor, azimuth
d. an erection chamber, pendulous vanes, space
a. mercury switches, torque motors, the local vertical
A gravity erector system corrects errors on a:
Select one:
a. turn co-ordinator
b. turn indicator
c. artificial horizon
d. DGI
c. artificial horizon
The air driven artificial horizon uses ………. gyroscope which is maintained ………. by means of ……….
The words which correctly complete the above sentence are:
Select one:
a. a free horizontal, case levelling
b. an Earth vertical, torque motors
c. an Earth vertical, pendulous vanes
d. a space vertical, torque motors
c. an Earth vertical, pendulous vanes
An artificial horizon has:
Select one:
a. 1 degree of freedom and a horizontal axis
b. 2 degrees of freedom and a vertical axis
c. 2 degrees of freedom and a horizontal axis
d. 1 degree of freedom and a vertical axis
b. 2 degrees of freedom and a vertical axis
A standby artificial horizon must have the following properties:
- a remote gyro
- its own power supply
- only to be used in emergency
- its own gyro
- one for each certified pilot
The combination regrouping all the correct statements is: Select one: a. 1, 2, 3, 4 & 5 b. 1, 3 & 5 c. 2, 3 & 4 d. 2 & 4
d. 2 & 4
An artificial horizon with an air driven gyroscope, (spinning anti-clockwise seen from above), is subjected to acceleration during a take-off run. As a result the instrument indications will falsely show:
Select one:
a. the right wing going up and the nose going down
b. the right wing going down and the nose going up
c. the right wing going up and the nose going up
d. the right wing going down and the nose going down
b. the right wing going down and the nose going up
During the take-off run, the air driven artificial horizon will indicate:
Select one:
a. a right turn due to the pendulosity of the outer gimbal
b. a right turn due to the action of the pendulous vanes
c. a nose-up attitude due to the action of the pendulous vanes
d. a nose-up attitude due to the pendulosity of the inner gimbal
c. a nose-up attitude due to the action of the pendulous vanes
Residual deviation Accuracy limits:
Direct reading compass +/- 10
Remote reading compass: +/- 1
Deviation increases:
with magnetic lattitude due to dip
Magnetic induction in softiron
increases with magnetic latitude
The contribution to deviation from longitudinal “B” aircraft magnetism is a function of…
a function of the sine of the heading
The contribution to deviation from lateral “C” aircraft magnetism is a function of…
a function of the cosine of the heading
The aims of compass swing are:
To observe and determine the deviations between magnetic north and compass north on a series of heading
To correct and remove as much deviation as possible
To record the residual deviation wich is left after the compass has been adjusted
A turn indicator consists of
a rate gyre with one gimbal around the vertical axis (Horizontal spin axis axis)
A skidding turn is a result of ………. bank, and the ball will appear to move in the ………….. direction
little, opposite
A slipping turn is a result of ………. bank, and the ball will appear to move in the ………….. direction
much, same
Which of the following factors will affect a turn indicator:
- angle of bank
- aircraft speed
- aircraft weight
Select one:
a. 2 & 3
b. all 3
c. 1 & 3
d. 1 & 2
d. 1 & 2
Under normal operating conditions, when an aircraft is in a banked turn, the rate of turn indicator is a valuable gyroscopic flight control instrument; when it is associated with an1 attitude indicator it indicates:
- The angular velocity of the aircraft about the yaw axis
- The bank of the aircraft
- The direction of the aircraft turn
- The angular velocity of the aircraft about the real vertical
The combination of correct statements is:
Select one:
a. 2, 4
b. 1, 3
c. 1, 2
d. 3, 4
b. 1, 3
In a left turn while taxiing, the correct indications on a turn and slip indicator are:
Select one:
a. needle left, ball right
b. needle right, ball left
c. needle right, ball right
d. needle left, ball left
a. needle left, ball right
The rate of turn shown on a turn indicator depends upon:
- bank angle
- aeroplane speed
- aeroplane weight
The combination regrouping the correct statements is:
Select one:
a. 2, 3
b. 1, 2
c. 1, 2, 3
d. 1, 3
b. 1, 2
Which of the following is true regarding the turn co-ordinator?
Select one:
a. its gyro is offset by 30° to the longitudinal axis of the aircraft
b. it gives angle of bank and rate of turn
c. it responds to rate of turn only
d. it has a tied gyroscope
d. it has a tied gyroscope
In a turn at constant angle of bank, the rate of turn is:
Select one:
a. independent of weight and proportional to TAS
b. dependent on weight and proportional to TAS
c. independent of weight and inversely proportional to TAS
d. dependent on weight and inversely proportional to TAS
c. independent of weight and inversely proportional to TAS
A turn indicator has which of the following:
- a vertical spin axis
- a rate gyro
- an Earth gyro
- one degree of freedom
- no degrees of freedom
Select one:
a. 2 and 4
b. 1 and 5
c. 2 and 5
d. 3 and 5
a. 2 and 4
he properties of a turn indicator are:
- one degree of freedom
- two degrees of freedom
- two springs connected to the aircraft frame
- spin axis in the longitudinal plane
- spin axis parallel to the yaw axis
- spin axis horizontal
The combination of correct statements is:
Select one:
a. 1 & 4
b. 1 & 6
c. 2 & 6
d. 2 & 5
b. 1 & 6
A compass swing is used to:
Select one:
a. align compass north with true north
b. align compass north with magnetic north
c. align magnetic north with true north
d. get true north and lubber line aligned
b. align compass north with magnetic north
Joint Airworthiness Requirements (JARs) state the maximum possible deviation after compensation of coefficients A, B and C are:
Select one:
a. One degree for a direct reading magnetic compass and eleven degrees for a slaved compass
b. One degree for a remote indicating compass and ten degrees for a direct reading magnetic compass
c. Eleven degrees for a direct reading magnetic compass and one degree for a remote indicating compass
d. Three degrees for a remote indicating compass and one degree for a direct reading magnetic compass
b. One degree for a remote indicating compass and ten degrees for a direct reading magnetic compass
An aircraft’s compass must be swung:
Select one:
a. if the aircraft has been in the hangar for a long time and has been moved several times
b. after a change of theatre of operations at the same magnetic latitude
c. every maintenance inspection
d. if the aircraft has been subjected to hammering
d. if the aircraft has been subjected to hammering
Aircraft magnetism caused by hard iron:
Select one:
a. varies directly with magnetic latitude
b. varies indirectly with magnetic latitude
c. is not usually influenced by the Earth’s magnetic field
d. is maximum on east and west
c. is not usually influenced by the Earth’s magnetic field
Earthrate formula:
-/+15 x sin(lat)
NH -
SH +
- Zero at magnetic equator
- Counter acted by LN
Transport wander:
eastern GS/60 x tan(lat)
NH -
SH +
*zero at north south
(Flying with the earth rotation)
A servo-assisted altimeter is more accurate than a simple altimeter because the small movements of:
the capsules are detected by a very sensitive electro-magnetic pick-off.
A temperature sensor has a recovery factor of 0,95. The temperature measured is equal to:
static air temperature (SAT) + 95% of the ram rise.
A turn indicator is an instrument which indicates rate of turn. Rate of turn depends upon: 1: bank angle 2: aeroplane speed 3: aeroplane weight The combination regrouping the correct statements is:
1, 2.
After the initial 90 degrees of a turn at constant pitch and bank, a classic artificial horizon indicates:
too much nose-up and too little bank.
An aircraft takes-off on a runway with an alignment of 045degrees; the compass is made for the northern hemisphere. During rolling take-off, the compass indicates:
a value below 045degrees.
At a low bank angle, the measurement of rate-of-turn actually consists in measuring the:
yaw rate of the aircraft.
Due to the rotation of the earth, the apparent drift of a horizontal free gyroscope at a latitude of 45degreesN is:
11degrees per hour to the right.
During a descent at a constant Mach number below the tropopause in ISA conditions:
IAS and TAS increase.
Given: Pt = total pressure Ps = static pressure Pd = dynamic pressure:
Pt = Pd + Ps
If the static source of an altimeter becomes blocked during a descent the instrument will:
continue to display the reading at which the blockage occurred
In a standard atmosphere and at the sea level, the calibrated airspeed (CAS) is:
equal to the true airspeed (TAS).
Machmeter readings are subject to:
Instrument error
position error
induced error
The apparent wander of a directional gyro is 15degrees/h:
At the North pole
The artificial horizon uses a gyroscope with: (note: the degree(s) of freedom of a gyro does not take into account its rotor spin axis.)
two degrees of freedom, and its rotor spin axis is continuously maintained to local vertical by an automatic erecting system.
The error induced by the location of the static pressure source is known as the:
position error.
The flux valve of a gyromagnetic compass:
1 - feeds the error detector
2 - feeds the direct indicating compass
3 - gives the earth’s magnetic field direction
The combination regrouping all of the correct statements is:
1, 3.
The limits of the white scale of an airspeed indicator are:
VSO for the lower limit and VFE for the upper limit
The parameter that determines the relationship between EAS and TAS is:
density altitude.
The velocity of sound at the sea level in a standard atmosphere is:
661 kt
In a gyromagnetic compass, the direction of the earth’s magnetic field is given by the:
flux valve.
On the airspeed indicator of a twin-engine aeroplane, the blue radial line corresponds to the:
best single-engine rate of climb.
The most significant advantages of an air data computer (ADC) are:
- Position error correction
- Hysteresis error correction
- Remote data transmission capability
- Gimballing errors correction
The combination regrouping all the correct statements is:
1,3
A direct reading thermometer consists of…..
two metals of different coefficients of expansion and are bonded together.
- Invar
- Brass
A remote reading thermometer works on which principle
change in electrical resistance in certain material
(whetstone bridge)
electrical fluctuaions does not affect readout
TAT probe air stagnation is preventet
using eng bleed air, to ‘suck’ in fresh air to measure
Air temperautur gauges
1) Instrument error
2) environmental error (solar heating, icing)
3) Heating error (friction heating on leading edges)
Aspirated TAT probe is
uses bleed air to prevent freezing
A remote reading thermometer depends upon ………. to indicate changes in temperature.
The words to correctly complete the sentence are:
change of electrical resistance with temperature
A direct reading aircraft thermometer usually consists of a bimetallic helix protruding into the airstream. Movement of the pointer over the temperature scale will depend upon:
Different coefficients of expansion of the two metals
Aircraft air temperature thermometers are shielded to protect them from:
solar radiation
SAT accurate formula?
EXAM
TAT / 1 + 0.2 x 0.9 x M2
temp in kelvin
The ADC (air data computer) takes in following measurements:
- PITOT
- STATIC
- AOA
- TAT
and calculates the rest
Given: Ts is the static temperature (SAT), Tt is the total temperature (TAT), Kr is the recovery coefficient and M is the Mach number. The total temperature can be expressed approximately by the formula:
Tt = Ts(1 + 0.2Kr.M²)
The difference between static air temperature and total air temperature is known as:
the ram rise
At a true airspeed of 500 knots, the ram rise will be approximately:
25°C
Use CRP-5
Total Air Temp is always ………. than Static Air Temp and the difference varies with ……….
The words to correctly complete the sentence are:
warmer, TAS
Total air temperature is:
The maximum temperature attainable by the air when brought to rest, adiabatically
CAS (RAS) is
errors
IAS corrected for:
- Instrument
- Position error
TAS is
CAS corrected for:
- density error
- Compressibility error (TAS>300kt)
An aircraft is flying at a constant CAS. If the ambient temperature ………. , the TAS will ………. due to ……….
The words to complete the above statement are:
rises, rise, decreasing density
When descending through an isothermal layer at a constant calibrated airspeed (CAS), the true airspeed (TAS) will
decrease
density
Compressibility error is caused by a false ………. of ………. pressure, requiring a ………. correction to the CAS to obtain EAS.
The words to correctly complete the sentence above are:
increase, dynamic, negative
increased pressure, overread AS
An aircraft maintaining a constant CAS and altitude is flying from a cold airmass into warmer air. The effect of the change of temperature on the speed will be:
TAS will increase
VLO
the maximum speed at which the landing gear may be retracted or extended
VLE
Max speed with landing gear extended
A pitot blockage of both the ram air input and the drain hole with the static port open causes the airspeed indicator to:
react like an altimeter
During a climb after take-off from a contaminated runway the total pressure probe of the airspeed indicator is blocked. The pilot finds that indicated airspeed:
increases steadily
The full International Standard Atmosphere (ISA) is assumed in the calibration of:
The pressure altimeter only
A vibrator may be fitted to an altimeter to overcome:
friction
The single most significant item which makes a servo altimeter more accurate is:
electromagnetic pick-off
On board an a/c, true altitude is shown from:
pressure altitude
Position/pressure error is
a result of turbulent airflow and suction around the source
If the static source to an altimeter becomes blocked during a climb, the instrument will:
continue to indicate the reading at which the blockage occurred
An aircraft maintaining a constant CAS and FL is flying from a warm air mass into a colder air mass. The effect of the change of temperature on the TAS and true altitude will be:
TAS will decrease and true altitude will decrease
What will the altimeter read if the layers beneath the aircraft are all colder than standard?
read higher than the real altitude
The value of mach 1 varies with
temperature
The ______ air, the _______ speed of sound
colder, lower
Local Speed of Sound formula
38.95 x Temp(K) ‘squared’
Mach meter errors
- Instrument error
- Position/pressure error
- Manouvre induced error
Mach meter PITOT leak
under read in climb
Mach meter STATIC leak
under read in climb
What is the speed of sound at 30,000 ft and -40°C?
595 kt
The machmeter consists of:
an airspeed indicator with an altimeter capsule
An aircraft is flying at FL390, temperature 207°A, at Mach 0.85. The TAS of the aircraft is:
476 kt
The mach number is the:
true airspeed (TAS) divided by the local speed of sound
At FL350 with an ISA deviation of -12, the true airspeed when flying at M0.78 is:
436 kt
Cruising at FL390, M0.84 is found to give a TAS of 499 kt. The ISA deviation at this level will be:
+17
Remember tropopause height 36000’
What is the speed of sound at 25,000 ft and -28°C?
610 kt
Sound propagates through the air at a speed which only depends on:
LSS
Temperature
C T M relation in an inversion
C M T
due to rising temp with alt
C TM relation in an isothermal layer
C T/M
An aircraft, flying at a constant altitude and Mach No, enters a warmer air mass. As a result:
the TAS will increase and the CAS remain the same
An aircraft is descending at a constant Mach No through an isothermal layer. The CAS of the aircraft will:
Increase
If an aircraft climbs at constant Mach No in ISA conditions, what happens to the TAS and the CAS?
Select one:
a. TAS decreases and CAS increases
b. TAS decreases and CAS decreases
c. TAS increases and CAS increases
d. TAS remains constant and CAS decreases
b. TAS decreases and CAS decreases
The indications of a machmeter are independent of:
Temperature
For an aircraft climbing at a constant Mach number below the tropopause in ISA conditions, the CAS will:
fall due to the decreasing density and decreasing TAS
Ways to increase rigidity in a gyo…
- Increase rotor mass
- increase the rotor diameter
- Concentrate the rotor mass around the perimeter of the rotor
- Increase the speed of rotation
Precessios in a gyro is…..
Any appliede for will effect the rotor 90 in the direction of rotation
