General

what is considered the basic building block of all matter

the atom

what is the most important law applicable to the study of electricity

ohms law

how is ohms law expressed as an equation

e=ixr , i = e/r , r=e/i

what are the elements of ohms law

voltage (e) , current ( i ) , resistance ( r)

what are four sources of electrical energy

thermal, light, pressure, chemical

what does a basic DC electrical circuit consist of

source (battery) , resistance or load (light bulb) , conductors (wires)

what represents capacitance in an AC circuit

a capacitor

what is the function of a capacitor

to store electricity

what is ther unit of measurement for capacitance

farad

what is the standard unit of measurement for frequency

hertz

what is the basic component that only allows current to flow in one direction

a diode

what is inductance

when voltage is induced by magnetic flux lines in a coil in an AC circuit

what is one advantage of AC circuits over DC circuits in an aircraft

space and weight can be saved

what is the definition of a short circuit

an unintentionally low resistance path between a componet/ conductor and ground

what is an example of an inductor in a magneto

the coil

what is impendance

ohms

what causes opposition to the flow of current in an AC circuit

inductive and capacitance reactance

what is the unit of measurement for impedance

ohms

what is the general purpose of a resistor

to limit current

how may the value of a small, fixed resistor be determined

by the color bands on the resistor

what are 2 things that happen when current flows through a conductor

a magnetic field is generated, and the conductor heats up.

what is the common name for the lines of the force that make up a field surrounding a magnet

magnetic flux lines

what is magnetism

the property of an object to attract certain metallic substances

What is the difference between permanent and temporary magnets

Permanent magnets retain magnetism and temporary does not

What is the concept that describes the relationship between electricity and magnetism

Electromagnetism

What are the four factors that affect the resistance of an electrical conductor

Wire gauge, length, temp and material

What is the unit of measurement of power in a DC circuit

The watt / amps times volts is watts 746 watts is 1 hp

What is a kilowatt

1000 watts

In a DC circuit what occurs when voltage is increased while resistance remains constant

There will be an increase in current

What are the three types of DC electrical circuits

Series, parallel, complex

A 24 volt lead acid battery has how many cells

12 cells, each cell is 2 volts

What is the most frequent cause of damage to solid state components and integrated circuits

ESD from human body due to careless handling

What are the units that battery capacity is measured in

Ampere hours

What should be the specific gravity of the electrolyte in a fully charged lead acid battery

1.275 and 1.300

What instrument is used to determine the specific gravity of electrolyte in a lead acid battery

A hydrometer

Why can a hydrometer NOT be used to determine the charge of a nickel-cadmium battery

The electrolyte specific gravity does not change with the state of charge

When using a hydrometer to check the charge of a lead acid battery at what temp must a correction factor be applied to the reading

Adjustments must be made if the temp of the electrolyte is above 90 or below 70 degrees

What is the effect of temp on specific gravity of the electrolyte when checking a lead acid battery

Battery temp changes from electrolyte density only when greater than 90 or less than 70 degrees

What is electromagnetic induction

It is the transfer of electrical energy by means of a magnetic field ( lines of flux)

How are battery compartments protected against corrosion

They are coated with special corrosion resistant paint (bituminous paint)

What should be the correct electrolyte level in a properly serviced battery

3/8 inches above plates

What are paralleling generators and how is load distributed

Two or more generators operated at same time to supply a load shared equally

Describe a no trip circuit breaker

Impossible to manually hold the circuit closed when excessive current is flowing. ( it pops when hot and won’t reset till cool)

Can you store nicad and lead acid batteries together

No fumes from lead acid contaminate nicad battery

Why should nicad and lead acid not be serviced in same area

Electrolyte and fumes from lead acid contaminate nicad battery

What could cause a nicad battery to fail to deliver its rated capacity

Cell imbalance or faulty cells

What is the result of an imbalanced cell in a nicad battery

When a cell has low resistance current increases causing it to heat up

What happens to the specific gravity of the electrolyte in a lead acid battery when temp changes

It varies with temp of electrolyte reading high or low

What is led

Light emitting diode

What is SLA battery

Sealed lead acid battery

What is basic unit of measure for inductance

Henry

What prevents reverse current flow in a DC alternator

Reverse current cutout

How many wires may be installed on a single terminal lug

Four

How do you identify wire types

Lettering on the insulation

Name functions of multimeter

volts amps ohms

How would a technician connect a multimeter in a circuit

Series

Name 2 types of resistors

Variable and fixed

What are 2 materials that conductors are made out of

Aluminum and copper

What component steps electricity up or down

Transformer

Describe a capacitor

2 plates with a dielectric in the middle

What is an inverter

An inverter changes electricity from DC power to AC power

What is diff between the conventional current flow theory and electron flow

CCFT is a visualization of current as flowing positive to negative, in actual practice electrons flow negative to positive ( electron theory )

What is kirchoffs voltage law

Algebraic sum of all voltages around a closed path or loop is zero

What is right hand motor rule

When the index finger of the right hand is pointed in the direction of the magnetic field and the second finger in the direction of current flow (thumb indicates direction current carrying wire moves)

What property is essential for metals used in making wire and tubing

Property of ductility

What is a nondestructive testing method for detecting surface cracks

Dye penetrant inspection

List steps of dye penetrant

1. Clean surface

2. Apply penetrant

3. Remove penetrant with water

4. Dry part

5. Apply developer

6. Inspect results

What are two types of self locking nuts

All metal, and fiber lock, or elastic stop nuts

What is the general rule for using self locking nuts

Do not use at joints which are subject to rotation

What type of cable is used in primary control systems

Extra flexible 7×19 cable

How can the correct “grip length” of a bolt be determined

Grip length should be total thickness of material being joined together.

The length of an standard bolts are measured in what fraction

8ths of an inch

What does the triangle mean on the head of a steel bolt

That it is a close tolerance bolt

What numbers are used for close tolerance bolts

An 173-186 for hex NAS 80 -86 for countersunk

What is the difference between a standard bolt and a close tolerance bolt

Close tolerance bolt is machined to more precise dimensions and used in high performance applications

A sold rivet diameter is always measured in what fraction

32nds of an inch

Describe a rivnut

Threaded body that is expanded to aircraft structure

What is the purpose of a channel nut and nut plate

Both nuts allow a screw or bolt to be installed without needing to hold nut with wrench

What are common materials for cotton pins to be made from

Low carbon steel and stainless steel

What is the smallest cable that can be used in primary control systems

1/8 inch in diameter

What should be the depth of penetration when making a fillet weld

25-50 percent

What precision measuring instruments are used to measure outside dimensions

Outside micrometer and vernier calipers

What term describes a metal that is based on iron

Ferrous alloy

What should be the width of the weld bead and depth of penetration when making a butt weld

3 to 5 times the thickness of the base metal and 100 percent penetration

What system is used to identify AN type aircraft bolts

Code markings on head of nut

What is the difference between a close tolerance bolt and regular AN bolt

Close tolerance bolts are for severe vibrations and load reversals and machined more precise and must be driven by hammer

What are steps for solution heat treating aluminum alloys

The alloy must be to a predetermined temp, heat soaked for a specific period, and rapidly quenched to low temp

In what state is aluminum alloy immediately after solution heat treating and quenching

Soft state, so material must be naturally aged, or precipitation hardened

What is done to prevent certain aluminum alloys from becoming hard after heat treating and quenching

Rivets are stored in fridge at temp lower than 32 degrees ( remain soft for 7 days / “ice box rivets” )

What do rivet head markings indicate

alloy of rivet

Why is alloy steel that is responsive to heat treatment usually less suitable for welding

Because it’s tendency to become brittle and loose it’s ductility around the weld

Why should steel be normalized after welding or machining

Remove internal stress of metal

What are two methods of case hardening

Carburizing and nitriding

What are the characteristics of a cold weld

Cold weld has improper penetration and cold laps caused by insufficient heat. Rough and irregular

What tools are used to measure outside dimensions only shafts, thickness of sheet metal stock, diameter of drills

outside micrometer or caliper

What should be used to make a visual inspection of a weld

A magnifying glass of at least 10x

Name some types of non destructive testing used on nonferrous materials

Eddy current, dye penetrant, xray , coin tap, visual inspection

Which NDT method can be performed without removing the surface coatings such as primer, paint, and anodized films and is effective in detecting surface and subsurface corrosion

Eddy current

What is most common type of corrosion

Surface corrosion