B2-7C #1 Upload

Knowledge Levels

• Basic knowledge regarding categories A, B1, and B2 are indicated in the allocation of knowledge levels which are indicated as 1, 2, or 3
• Category C applicants are required to meet either the category B1 or the category B2 basic knowledge levels

Level 1 Objectives:

• Applicants should be familiar with the basic elements of the subject.
• Applicants should be able to give a simple description of the whole subject, using common words and examples.
• Applicants should be able to use typical terms.

Level 2 Objectives:

• Applicants should be able to understand the theoretical fundamentals of the subject.
• Applicants should be able to give a general description of the subject using typical examples
• Applicants should be able to use mathematical formulae in conjunction with physical laws describing the subject.
• Applicants should be able to read and understand sketches, drawings and schematics describing the subject.
• Applicants should be able to apply their knowledge in a practical manner using detailed procedures.

Level 3 Objectives:

• Applicants should know the theory of the subject and interrelationships with other subjects.
• Applicants should be able to give a detailed description of the subject using theoretical fundamentals and specific examples.
• Applicants should understand and be able to use mathematical formulae related to the subject.
• Applicants should be able to read, understand and prepare sketches, simple drawings and schematics describing the subject.
• Applicants should be able to apply his knowledge in a practical manner using manufacturer's instructions.
• Applicants should be able to interpret results from various sources and measurements and apply corrective action where appropriate.

Electrical Measurement Instruments

• Devices are needed to measure electrical quantities to maintain modern devices
• Technicians need to measure current, voltage, resistance, and power.
• Electromagnetism is the most common principle used for electrical measurements.
• The strength of an electromagnetic field is proportional to the amount of current that flows in the coil.
• Voltage, resistance, and power all relate to a flow of current.

Common Electrical Measuring Instruments

• The most common electrical measurement tools to use are multimeters, meggers, ohmmeters
• Digital meters are most common meter in use, but occasionally analogy meters are required

Analogue Meters

• Allows trends to be identified in circuits by looking at a needle
• Indicate the interference induced into a wire by neighboring circuits.
• Analogue meters connect the circuit being testing to load so ghost voltages are voltage only and effectively cancelled out

D'Arsonval Meter Movement

• Analog meters often use the d'Arsonval meter movement principle
• A basic DC type of meter movement, which was used in electrical measurement
• Is a current-measuring device used in ammeters, voltmeters and ohmmeters
• The pointer deflects proportionately to the current through the coil
• Also functions as an ammeter, voltmeter, and ohmmeter.
• Reference magnetic field created by a horseshoe shaped permanent magnet with a cylindrical keeper to concentrate the field
• The current creates creates its own magnetic field that opposes the permanent magnetic field
• The two fields are placed in opposition until hairspring calibrate forces from the magnetic field cause rotation
• Zero adjustment is accomplished via a slotted screw on the case front

Permanent-Magnet Moving-Coil (PMMC) Meter Design

• The design is based on a D'Arsonval meter movement
• Wire coils wound on an aluminium frame or bobbin
• Bobbins supported by jeweled bearings to allow movement
• Hairsprings are used to revert the coil to the original position with no current present, and also used to make electrical connections to the coil
• When current runs through the coil, the magnetic field increases, causing the coil to move
• A reference scale is used to measure coil movement

Additional Meter Features

• An iron core is placed inside of the coil to concentrate the magnetic fields
• Curved pole pieces are attached to the permanent magnet to ensure a steady increase in coil turning force as the current increase

DC Ammeter

• A device that measures current
• Electric currents are measured in amperes (A) with smaller values measured in milliammeters or microammeters
• DC ammeters must be connected with the correct polarity "+" terminal should be connected toward the positive side, and - toward the negative side
• Current must pass through the load and the meter
• Always connect in series with the circuit path
• Connecting in parallel can damage the equipment

Ammeter Shunts

• To measure a range of currents greater than the full scale current of a meter, install a shunt in parallel
• Shunt is a type of resistor that is connected in parallel with a meter that increases the amount of current it can measure
• Load current flowing through a shunt produces a voltage drop proportional to the current
• Shunts are designed to carry a fixed high proportion of measured current
• Shunts may be in the ammeter or external to it, with remote external shunts used in high current cables

Ammeter Shunt Resistance

• A standard d'Arsonval meter movement may have a current sensitivity of 1 mA and a resistance of 50 Ω.
• A shunt resistor is required to measure more than 1 mA and bypass current that exceeds the 1-mA limitation of the meter movement.

Example

• To measure 10 mA with a 1-mA meter, the shunt should carry 9 mA while allowing 1 mA through the meter.
• Due to shunt and meter resistance being in parallel the voltage drop across them is the same: Esh = Em
• Using Ohms Law: ESH = ISH × RSH EM = IM × RM ISH × RSH =IM × RM Thus, RSH =IM /ISH X RM = 1mA × 50 Ω9 mA = 5.56 Ω

Multi-Range Ammeter

• Several shunt resistors and a switch are used to select desired max current
• An ammeter has different maximum current readings
• Ammeter has five ranges selected by a switch (100 μA; 1, 10 and 100 mA; 1 A)
• The 100µA position routes all current through the meter movement, while the shunt resistors aren't used
• The 1-mA position creates paths with the meter movement and shunt resistors (R1, R2, R3 and R4)
• Only some of the current will go through the meter movement and the shunt resistors
• More current flows through shunt resistors with less shunt resistance
• Meter movement has more current if the current exceeds range selected
• It is important that the shunt resistor is known accurately, since it is uses to protect a meter

Ammeter Range Selection

• Having a proper range selection switch
• Excessive current will damage the meter if the current being measured is larger than the scale
• Therefore, important to always start with the highest range when using an ammeter
• When the current can be measured on several ranges, use the range that creates a reading near the middle of the scale

Voltmeters

• Voltmeters measures the voltage between two points in an electric circuit
• It uses the same type of meter movement as the ammeter and a different circuit than one used on ammeters
• Analogue voltmeters move a point and scale proportionally to the voltage and digital shows a numerical display with an analogue to digital converter

Basic Multimeter Design

• Consist of multirange DC ammeter, voltmeter and ohmmeter packaged as one.
• Two categories exist; digital and analogue devices

Measuring Resistance, Voltage and Amperage in Circuit

• Switching to "A" indicates ammeter shunt is connected creating a parallel meter for reading as an ammeter
• Using "V" indicates multiplier is connected to series, allowing voltmeter to measure
• The range of the multiplier is determined by the value of the multiplier
• Setting the meter to"O" indicates the meter is connected with the battery in circle to measure ohms
• The lead polarity has is reversed to maintain proper direction through the meter.

Analogue Mutimeters

• Typically have a sensitivity of 20 000 Ω/V for measuring DC and 1000 Ω/V for measuring AC
• All analogue mutimeters have a 'Zero Q Adjust' knob/dial to zero the scale
• Analog meters are useful fore testing potentiometers and provide accurate indications for possible high resistance joints

Digital Multimeters

• A digital multimeter display indicates the measure quanity as a number and prevents parallax errors
• It's use by aircraft technicians includes being easy to use, compact, accurate auto-ranging and usable in any position if neccessary

Multimeter Usage

• It Is important that these process guidelines are followed correctly
• De-energise and discharge the circuit before doing anything
• Never apply power to a circuit while measuring resistance
• Connect the multimeter in series with the circuit before doing current measurements and in parallel for measuring voltage

Precautions on Using Mutimeters

• Ensure the mutimeter switched to AC before attempting AC circuits
• Observe proper DC polarity
• When finished with mutimeter, switch it to the OFF position or if there is no OFF position, switch the multimeter to the highest AC voltage position.
• Always start with the highest voltage or current range then finalise and scale the reading to the middle of the scale.
• Adjust O Ω reading after changing resistance and before measurement

Current Transformers

• Transformers scale primary currents to easier to measure secondary currents using various size and shape solutions
• In relation to the winders, ratios determine relation between the input and output currents
• AC current is generally connected in series with the load; the CT has a 1A or 5A secondary to the input of measure equipment

Transformer Connections

• Connect the transformers CT leads to a ammeter or short together and avoid high voltage with leads left unconnected
• CT enables metering equipment to measure above range of the meter
• DC magnetic fields don't oscillate and it is difficult to produce output
• DC currents are sensed via a DC magnetic field on a self transmitted AC magnetic
• AC signals sense how much DC influences the AC field.

Clamp Meter

• Output of transformer often advantageous in adapting moving coil instruments via voltage and current
• Multi-range rectifier type used because of non linear accuracy range
• Rectifier and moving coil ammeter requires so little over used that few ampere turns require for use

Clamp Meter Measurement

• The meter encloses the conductor to be measured as designed with a magnet in the coil
• A strong spring trigger ensures that an adequate pressure releases the core

Multiple Functions of Clamp Meter

• The cable circled comprises with the primary winding and uses a single/ac or dual ac with dc in addition
• The Hall Effect type (AC or DC or both) is used to gauge AC only

Meter General Safety Precautions

• Meters have risk of electric shock from operating electric circuits
• Important when using electric measuring equipement to use equipment to meet safety standards, calibration and placed away horizontal surfaces
• Fused current inputs, inspect leads for wear using shielded connectors
• Select the proper function and a highher range to select

Avionics General Test Equipment (7.4) Learning Objectives

• Demonstrate the operation/function/use of avionics general test equipment at level 3
• Demonstrate compliance and calibration requirements of avionics general test equipment at level 3
• Demonstrate the appropriate safety precautions of avionics general test equipment at level 3
• Test Equipment needs to be capable of performing normal tests

Testing procedures

• First equipment must be approved by the manufacturer and within calibration
• Second the tester must compare specifications of equipment

Logic Probes

• Logic Probes sense to state conditions in logic circuits that are either high or low
• An IC logic prove can be tested by comparing it to a known functional IC.

Operation of Logic Probes

• Logic probe are used for troubleshooting since in can quickly test if the point is low, high open or pulsing. They usually are directly to the power, some with internal batteries
• IC failures show show as constant low and high levels; provide a method
• Red = High
• Green = Low
• Low lit dimly = high frequency pulse train

Oscilloscopes

• One of the most important measurement instrucments used for complex circuits
• Sophisticated voltmeter and two dimensional graph display
• Measures the voltage and frequency of an electrical signal
• Measures a video pulse appearing of selected test joint

Oscillosopes Accuracy

• Oscilloscopes may video pulses with accurate functions of the same way if scope operates
• Can be either be anode or digital

Video Pulses and CRT Display

• CRT displays controlled election beams
• AC voltmeter measures the output size of a the signal generator and is connected in parallel
• The voltmeter measures the dC value which is root mean squared voltage.

Decade Boxes

• Box that assembles of precision for resistance, coil and capacitance, it's used for load substituion
• Includes several sections which include sub-multiples and multiples of 10
• Turning the dial to a desired range is possible

Radio Frequency Testing

• A typical RF signal generator contains: Oscillator circuit
• modulator
• Output control

Modulation During RF Testing

• The internal/External source of mofication from a waveform to a generator
• Metal shielding is used to block the unit and has a representative block diagram
• Function will produce the signal on a generator

Radio Frequency

• The oscillator circuit is depended of the range of frequencies
• Low Frequency signal have groups of coil and use a variable capacitor.
• It use select switch on capacity to provide the LC circuit
• Modulation circuit also produced with an audio voltage by a oscillator

Adjusting Voltage in Radio Testing

• Calibrated networks are used to regulate the correct voltage to test
• Attenuators regulators and correct the frequency for test
• Attenuator network is resistors and have range selections in the circuit

RF Directional Wattmeter Functions

• A meter used for forward or reflected power
• Its insserted into the load or radio frequency range elements and then is rotated
• Typically if an impedance matches the power transmitter, all the power is irradiated out,
• Reflected back to the transmitter it is a reflected line

Computing Forward and Reflected Power

Pf = Vf²/Z = If²Z, where Z is line impedance with forward P₁ = V²/Z = Ir2Z with reflected

• Power for test is calculated by forward power less the reflected power
• Most RF Wattmeter use standard 50 Ohm
• SWR test will be measured forward and reflected
• With a 3:1 SWR is a 3/greater than the maximum amplitude

Other Applications of the Wattmeter

• Can also defined in terms of current and Power wave
• Note to not permanently damage with high high SWR transmitter
• A diagram is used to measure the load and match in a 50 Ohm coaxial transmission lines

Bird Plug In Element

• To measure measurements plug an element and rotate and set the arrow to the load to measure forwad power and point is to the power for reflective power
• The meter is not zeroed, then the position can have presence can have a rest on zero

Attenuator

• An device that reduces the amplitude of power from a signal from distorting
• Amplifier has a gain an attenuator provides loss with less than 1 passive deviator network
• RF attenuator is an RF component that reduces the signal used typically in close tolerates typically less than 1
• Shunt Resistors provide various resistances by using a resistor and switing the resistors

Attenuator Probe Operation

• An attenuator probe contains and intneral high value resistor in series with the probe tip
• The probe gives the higher impedance than that of the oscilioscope and gives it higher impedence
• Schematic is created using in the probe
• Is important before and and can adjusted that cable that an is the correct impedence for the signal

Time-Domain Reflectometer Function

• Is used to measure the length for cable, coaxial, and parrellel conductors that two are conduct from one end
• TDR transmitt pulses that have shapes amplitude into ends, at a the speak the type the fautl and enables a accurate the fault

Volcity Propagation Testing

• V is a measure off signal travels,radio signal in its appoximatley 380,0088 M/Sec. and that
• V is statement of the speed of light and of the time and distance
• Used to inspect type of damages like: CRIMPT, frayED CABLE, open, short

Avionics Test Set

• The INav is design tested to function and calibrated of Comm
• The test sets to be used bench and tester
• The tester have a signal generating systems and has a good monitor VOR output with localizers
• The rf meter come with all necessary and the build in can create generation can create power.

Michelin 2210 tester

• Test signals with localizers for VOR MKR and Comm
• Has modulations for crystal
• Higher RF power to be precise

IFR 4000

• Compacy weigh light test unit. It's design tester transceivers

###ATC/DME Tester

• is design to tested in as well in aircraft used with operation signals in comprised with the pulse group PG
• It's comprised with a pre of approximately

Distance measuring equipment

• consists if portable units which typically operated on an internal batery. A tent set come it antenna and specify the distance ftrom AC
• The equipment has simulatored and used by transponder system, variable can

Pitot-Static Test -Sets

• Altitude indications, Alspeed indications,
• Vertical speed indications climb descent) -Air Data Copmuter operation
  • Transposed a simulated altitude -Cabin pressurization warnings -The possible presence of pitot and static ports systems

Static Dischargers

• and used used is a to to. a that within bonding.

Additional Information Notes on Aircraft Testing And Installation

• The racks had an additional set the wrong, to into that .The will is place place
• Use that in and in place the to nothing damaged as lock ben

Avionics Assembly and Disassembly Techniques

• Removal and refit of components are described in the Maintenance Manuel, or known as common sense knowledge
• The Maintenance Manual always used as the primary reference

Standared Gromets and Enviromental conditions.

• Is also table to help show various rating and what they can withstand
• A cu at 45⁰ can be inatall for gromets install, that install

Terminal Lugs and Boards

• Terminals are and what they support, terminals need to four are on to
• Terminal are on to where install a that is to must at at.

Connector and Plug Inspection

• Any join that conductors is used in sockets

Common Connector Failures:

• Contamination/corrosion. Bent pins Push in sockets
• Once connected use of locking devcie is pushed before
• They can't turn out

Wire Connections

• Wire needs to placed in a in to is this and without but an the be the to tool
• This what be to is or crew tool

Notes to be Mention on Wiring to Installation

• Precautions covered in Module 5 are to always do not.
• Do touch what the is and to have that, in have to