M7 B1 - B2
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- Created by: Bikboi
- Created on: 02-10-24 10:34
What do avionics systems contain?
Built in test equipment (BITE)
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How are BITEs limited?
Cannot perform self tests and can indicate a system is serviceable when it is not.
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How are power measurements achieved?
Wattmeter
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How is power calculated?
V x I
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How is wattmeter movement also referred to?
Dynamometer movement
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What is dynamometer movement?
Similar to moving coil movement as lightweight coil is attached to pointer
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What is used instead of a permanent magnet within a wattmeter?
Stationary Coil
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What does the stationary coil of a wattmeter provide?
Magnetic field
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What is energised by the moving coil of a wattmeter?
Voltage
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What is energised by the stationary coil of a wattmeter?
Current
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What ensures that full voltage is not applied to a wattmeter?
Moving coil connected in series with a range resistor
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Where is the safe rating of a wattmeter displayed?
On the instrument in volts and amperes
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What is the DC equivalent to frequency in an AC circuit?
There is no equivalent to frequency within DC circuits
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When is frequency measurement important?
Systems designed to run efficiently at only one frequency
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What is a tank circuit?
Parallel inductor and capacitor
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What form of circuit is used within a frequency meter?
Tank
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What are the adjustment knobs used for on a resonant frequency meter?
Calibrated to show resonant frequency and read when maximum indication is shown on meter
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What type of filter circuit is a resonant frequency meter?
Tunable
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What condition must a bridge circuit be in before being read?
Balanced for a null condition
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What technique is used by a frequency counter?
Digital counting
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What does a frequency counter consist of?
Accurate clock signal source, Gate circuit and a digital counter
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What is used to display indication of a frequency counter?
LED or LCD
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When are pulses counted by a frequency counter?
When gate circuit is open
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What controls the time that the gate circuit is open for?
Accurate clock signal
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How is frequency calculated within a frequency counter?
Pulse count divided by time
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How is a frequency counter counting technique referred?
Direct digital counter
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What is the most accurate and easy to use method of frequency measurement?
Frequency counter
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How can the frequency range of a frequency counter be extended?
Prescaler between input and counter
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What is a prescaler?
A digital circuit (Binary counter) that divides frequency by a constant
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What is the limit of a frequency counter?
1 GHz
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How is the limit of a frequency counter determined?
Maximum speed of digital logic
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What are oscilloscopes used for?
Time related voltage waveforms and frequency/voltage measurements
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What is the most important use of an oscilloscope?
Display of time related voltage waveforms
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What is used to project electrons between deflecting plates in an oscilloscope?
Grids form an electron gun
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What is used on a screen of an oscilloscope to a produce luminous spot that remains when electrons are moved/interrupted?
Phosphorescent material
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What is the intensity of an oscilloscope determined by?
Quantity of electrons and their velocity
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What is the potential at G1 in oscilloscopes?
Negative with respect to the cathode
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What is the potential at G1 relative to?
Quantity of electrons
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What controls the brightness of the illuminated spot?
Quantity of electrons
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What is used to accelerate the electrons in an oscilloscope?
G2 and G3
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What is used to focus the electron stream?
Electrostatic field set up by difference between G2 and G3
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How is the position of the spot on an oscilloscope determined?
Voltages applied to X and Y deflecting plates
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How is horizontal movement in an oscilloscope achieved?
Proportional to X plate potential difference
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What determines the vertical movement of an oscilloscope?
Y plate potential difference
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What establishes the potential difference across X and Y plates?
X and Y amplifiers
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What is the graphical representation formed on an oscilloscope?
Voltage as a function of the other voltage
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How must signal waveforms be displayed?
Function of time
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What does a timebase circuit supply?
Voltage that varies linearly with time
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What is timebase circuit usually supplied to?
X plates and the signal to be observed is applied to Y plates (Vertical)
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What is the (T1) sweep in relation to time base?
The time it takes the spot to move linearly from left to right on the screen
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What is the (T2) fly back time in relation to time base?
The time it takes the spot to turn to start a new cycle which is usually much shorter than the sweep
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What can occur during the fly back time?
Blank screen generated by a negative pulse applied to G1 (Control grid) via timebase
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If T1 (Sweep) is the same as or a multiple of the periodic time on the Y plates, what is obtained?
Stationary display of voltage variations with time
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How can the time for one complete cycle be described?
Width of 1 cycle / time base (horizontal deflection)
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What do pitot/static systems supply to the aircraft?
Static and dynamic air pressures to aircraft instruments
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What maintenance stage should leak checks be carried out?
All instruments connected
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How do test sets measure instruments?
They are pressure generators and simulate aircraft conditions
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How are pitot/static system test sets also referred to?
Air data test sets or air data test equipment
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What is the most basic type of pitot/static test set?
Hand held units (Bryans leak test)
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Why must pressure be applied to equipment at correct rates?
Equipment can be damaged by pressures applied at incorrect rates
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When must connection/disconnection of test sets be completed?
Ambient conditions
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What requirement must modern test sets meet?
RVSM (Reduced Vertical Separation Minimal)
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What are pitot/static system test sets used in conjunction with?
ATC/TCAS and ADS-B tests
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What is the most ideal point to connect a pitot/static system test set?
A point that can be readily inspected after being returned to stand configuration
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When must a leak check be carried out?
Whenever system is disturbed
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What are the 2 types of leak check carried out?
Check system operation and ensure system doesn't lose pressure.
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What is used for low pressure leak checks?
Pitot/Static leak checks
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What is the purpose of the low pressure pitot static leak check?
Quick verification of system integrity
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If any suspicion of a leak if found during low pressure leak check, what must be carried out?
Full range leak check
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What are the required items for a low pressure leak check?
Air speed indicator and handpump to create pressure and vacuum
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What is the airspeed indicator used for in a low pressure leak check?
Reference to ensure correct pressure (pitot) / vacuum (static) is being generated
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When are air data test sets used?
High range checks and calibration of instruments and systems
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What is an additional function of an air data test set?
ATC transponder mode C altitude reporting function tests
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What is contained in an air data test set?
Pressure pump and vacuum pump (hand operated or electrically operated)
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How are pumps within digital air data test sets controlled?
Programme
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What is contained within the assembly of an air data test set?
Calibrated altimeter, Vertical speed indicator and airspeed indicator
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How are indications represented on a digital test set?
Digitally
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Other cards in this set
Card 2
Front
How are BITEs limited?
Back
Cannot perform self tests and can indicate a system is serviceable when it is not.
Card 3
Front
How are power measurements achieved?
Back
Card 4
Front
How is power calculated?
Back
Card 5
Front
How is wattmeter movement also referred to?
Back
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