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Airframe Test > Electrical System > Flashcards

Electrical System Flashcards

1
Q

What is Ohm’s Law?
What is the formula?

A

States that the current through a conductor is directly proportional to the voltage applied to that conductor and inversely proportional to the resistance of the conductor

E = I x R
E = Electromotive force in volts
I = Current flow in amps
R = Resistance measured in ohms

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2
Q

Describe a DC Generator

A
  1. transform mechanical energy into electrical
    energy
  2. produce direct current (DC)
  3. typically found on light aircraft
  4. requires a control circuit to generator
    maintains correct voltage and current
  5. normally maintains a nominal output voltage
    of 14 volts or 28 volts
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3
Q

What are the 3 mains parts (assemblies) of DC generators

A
  1. Field frame
  2. Rotating armature
  3. Brush assembly
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4
Q

What are the 2 functions of the field frame in a DC generator

A
  1. to hold windings needed to produce a
    magnetic field
  2. to act as a mechanical support for the other
    parts of the generator
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5
Q

Generators -
Things to Know
How do they work?

A
  1. Voltage is induced in the armature throughout
    the entire 360 degree rotation of the
    conductor
  2. The armature is the rotating portion of a DC
    generator
  3. Slip rings & brushes can be used to transfer
    electrical energy from the rotating loop to the
    stationary aircraft loads
  4. The slip rings are connected to the loop and
    rotate / usually a copper material
  5. The brushes are stationary and allow a
    current path to the electrical loads / made of
    a soft carbon substance
  6. AC voltage is supplied to the slip rings
  7. A commutator is used to change the AC to DC
    voltage
  8. By replacing the slip rings of the basic AC
    generator with two half cylinders ( the
    commutator), a basic DC generator is
    obtained
  9. the red side coil is connected to the red
    segment
  10. the amber side of the coil is connected to the
    amber segment
  11. the rotating parts of a DC generator (coil and
    commutator) are called an armature
  12. The red brush is always in contact with the
    coil side moving downward
  13. The amber brush is always in contact with
    the coil side moving upwards
  14. Commutator action causes the current to
    flow always in the same direction through
    the external circuit or meter
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6
Q

The rotating parts of a DC generator (coil and commutator) are called what?

A

Armature

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7
Q

What parts make up the Armature in the DC generator?

A

The coil and the commutator

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8
Q

Describe the construction of the field frame

A
  1. The actual electromagnetic conductor is
    wrapped around pieces of laminated metal
    called field poles
  2. The field poles are typically bolted to the
    inside of the frame and laminated to reduce
    eddy current losses; they also concentrate the
    lines of force produced by the field coils
  3. Field coils are made up of many turns of
    insulated wire / usually wound on a form that
    fits over the iron core of the pole
  4. DC current is fed to the field coils to produce
    an electromagnetic field.
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9
Q

Describe the armature of a generator

A
  1. consists of two primary elements
    a. the wire coils (called windings) wound
    around an iron core
    b. the commutator assembly
  2. Windings are evenly spaced around the
    armature and mounted on a steel shaft
  3. the armature rotates inside a magnetic field
    produced by the field coils
  4. the core of the armature acts as an iron
    conductor and is laminated to prevent the
    circulation of eddy currents
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10
Q

What are the 2 primary elements of the armature?

A
  1. wire coils (called windings) - wound around an
    iron core
  2. the commutator assembly
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11
Q

Describe the core of the armature

A

the core of the armature acts as an iron
conductor and is laminated to prevent the
circulation of eddy currents

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12
Q

Describe the commutator in a generator

A
  1. located at the end of an armature
  2. consists of copper segments divided by a thin
    insulator
  3. the insulator is made from mineral mica
  4. the brushes ride on the surface of the
    commutator forming the electrical contact
    between the armature coils and the external
    circuit
  5. A flexible, braided copper conductor called a
    pigtail, connects each brush to the external
    circuit
  6. commutator surface is highly polished to
    reduce friction
  7. never use oil or grease on a commutator
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13
Q

What are the brushes made of and why?

A
  1. high grade carbon
  2. brushes wear out and need regular attention
    or replacement
  3. the brush must be quite large to provide a
    current path for the armature windings
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14
Q

What are the 3 types of DC generators?

A
  1. series wound
  2. parallel (shunt) wound
  3. series parallel (compound wound)
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15
Q

What is the external circuit?

A
  1. the electrical load powered by the generator
  2. used for charging the aircraft battery and
    supplying power to all electrical equipment
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16
Q

Describe Series Wound DC Generators

A
  1. contains a field winding connected in series
    with the external circuit
  2. have very poor voltage regulation under
    changing load
  3. when aircraft electrical load increases - the
    voltage increases / when aircraft electrical
    load decreased - voltage decreases
  4. Since it has poor voltage and current
    regulation - it is never employed as an
    airplane generator
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17
Q

Describe Parallel (Shunt) Wound DC Generators

A
  1. a generator having a field winding connected
    in parallel with the external circuit
  2. In electrical terms, shunt means parallel
  3. Any increase in load causes a decrease in the
    output voltage . any decrease in load causes a
    increase in output voltage
    4.
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18
Q

In a Parallel (Shunt) Wound DC Generator, any increase in load causes a decrease in the
output voltage and any decrease in load causes a increase in output voltage. Why ?

A

This occurs since the field winding is connected in parallel to the load and armature, and all the current flowing in the external circuit passes only through the armature winding (not the field).

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19
Q

How can the output voltage of a shunt generator be controlled?

A

a rheostat inserted in series with the field windings

OUTCOME:
Field circuit resistance increases - field current reduced and generated voltage reduced

Field current resistance decreases - field current increases and generated voltage increases

** In actual aircraft, the field rheostat would be
replaced with an automatic control device,
such as a voltage regulator**

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20
Q

Describe a Compound Wound DC Generator

A
  1. employs two field windings
    a. one in series
    b. one in parallel with the load
  2. the output is relatively constant, even with
    changes in load
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21
Q

Generator Ratings
1. how are they rated
2. things to know

A
  1. generators are typically rated for their voltage
    and power output
  2. each generator is designed to operate at a
    specified voltage, approximately 14 or 28 volts
    (aircraft electrical systems are designed to
    operator at one of these two voltage values)
  3. aircrafts voltage depends on which battery is
    selected for the aircraft
  4. batteries are either 12 or 24 volts when fully
    charged
  5. the generator selected must have a voltage
    output slightly higher than the battery voltage
    • hence the 14 or 28 volt generator ratings
  6. the generator drive is usually geared to turn
    the generator between 1 1/8 and 1 1/2 times
    the engine crankshaft speed
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22
Q

What information is stamped on the generator nameplat?

A
  1. generator rating
  2. generator performance data
  3. direction of rotation
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23
Q

Why is it important to use a generator with the correct rotation?

A

the polarity of the output voltage will be reversed if a generator with the incorrect rotation is used

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24
Q

What is “coming in” speed?

A
  1. speed at which aircraft generators produce
    their normal voltage
  2. usually about 1500 rpm
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25
Q

In general, the inspection of the generator installed on an aircraft should include the following 6 items

A
  1. security of generator mounting
  2. condition of electrical connections
  3. dirt and oil in the generator
    • if oil is present - check engine oil seals
    • blow out any dirt with compressed air
  4. condition of generator brushes
  5. generator operation
  6. voltage regulator operation

always follow manufacturers instructions for
any given generator

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26
Q

What is the recommended procedure to seat brushes that do not make good contact with the slip rings or commutators?

A
  1. Lift the brush sufficiently to permit the
    insertion of a strip of extra-fine 000(triple
    aught) grit, or finer, sandpaper under the
    brush, rough side towards the carbon brush
  2. Pull sandpaper in direction of armature
    rotation
  3. Sand the brush only in the direction of
    rotation
  4. thoroughly clean any carbon dust from all
    parts of generator
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27
Q

What is the Generator control system?

A
  1. designed to keep the generator output within
    limits for all flight variables
  2. often referred to as voltage regulators or
    generator control units (GCU).
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28
Q

What are the 2 basic types of generator controls?

A
  1. electro-mechanical
  2. solid-state (transistorized)
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29
Q

Describe electro-mechanical general controls

A
  1. found on older aircraft
  2. tend to require regular inspection and
    maintenance
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30
Q

Describe solid-state generator controls

A
  1. more modern
  2. typically considered more reliable
  3. more accurate generator output control
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31
Q

What are the six functions of the generator control system?

A
  1. Voltage regulation
  2. Overvoltage protection
  3. Parallel generator operations
  4. Overexcitation protection
  5. Differential voltage
  6. Reverse current sensing
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32
Q

Voltage Regulation is a function of the generator control system - what does this mean/ what does it do?

A

a. regulation unit takes sample of generator
output and compares to a known reference

b. makes adjustments to generator field
current when necessary

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33
Q

Overvoltage Protection is a function of the generator control system - what does this mean/ what does it do?

A

a. compares sampled voltage to a reference
voltage
b. used to open relay that controls the field
excitation current
c. typically found on more complex generator
control systems

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34
Q

Parallel Generator Functions is a function of the generator control system - what does this mean/ what does it do?

A

a. on multiengine aircraft
b. ensures all generators operate within limits
c. compares voltages between 2 or more
generators and adjusts voltage regulation
accordingly

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35
Q

Overexcitation Protection is a function of the generator control system - what does this mean/ what does it do?

A
  1. The overexcitation circuit often works in
    conjunction with the overvoltage circuit to
    control the generator

when one generator in a parallel system fails, one of the generators can become overexcited and tends to carry more if its share of the load - this causes the generator to produce too much current

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36
Q

Differential Voltage is a function of the generator control system - what does this mean/ what does it do?

A

this function is designed to ensure all generator voltage values are within a close tolerance before being connected to the bus.

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37
Q

Reverse Current Sensing is a function of the generator control system - what does this mean/ what does it do?

A
  1. Monitors the system for a reverse current
  2. Reverse current indicates that current is
    flowing to the generator and not from the
    generator
  3. If this occurs, the system opens the generator
    relay and disconnects the generator from the
    bus
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38
Q

What is a starter generator

A
  1. high output generator found on turbine
    powered corporate type aircraft
  2. it is a generator and starter combined into
    one unit
  3. performs 2 tasks: engine starting and
    generation of electrical power
  4. unit contains two sets of field wingdings
    one field is used to start the engine
    one field is used for the generation of
    electrical power
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39
Q

Wiring Diagrams
- what is it used for
- what information is included
- where are they found

A
  1. wiring diagrams are included in most aircraft
    service manuals
  2. information included:
    a. size of wire
    b. type of terminals to be used
  3. identifies each component in a system by its
    part number, serial number, and any changes
    made during the production run of the aircraft

Wiring Diagrams are often used for
troubleshooting electrical malfunctions

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40
Q

Block Diagrams
- what is it used for?
- what is included?

A
  1. used as an aid for troubleshooting complex
    electrical and electronic systems
  2. consists of individual blocks that represent
    several components, such as a printed circuit
    board
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41
Q

Pictorial Diagrams
- what is it used for
- when is it used

A
  1. pictures of components are used instead of
    conventional electrical symbols found in
    schematic diagrams
  2. helps the maintenance technician visualize
    the operation of a system
42
Q

Schematic Diagrams
- what is it used for
- when used

A
  1. used to illustrate a principle of operation
  2. it does not show parts as they actually appear
    or function
  3. it indicates the location of components with
    respect to each other
  4. best utilized for troubleshooting
43
Q

What is a wire?

A

a single, solid conductor or a stranded conductor covered with an insulating material

44
Q

The term “cable” as used in aircraft electrical installations includes
Hint: there are 4

A
  1. two or more separately insulated conductors
    in the same jacket
  2. two or more separately insulated conductors
    twisted together (twisted pair)
  3. One or more insulated conductors covered
    with a metallic braided shield (shielded cable)
  4. A single insulated center conductor with a
    metallic braided outer conductor
    (radio frequency cable)
45
Q

What is a wire harness?

A

The term “wire harness” is used when a array of insulated conductors are bound together by lacing cord, metal bands, or other binding suitable for use only in specific equipment for which the harness was designed

46
Q

What is the standard wire used in light aircraft?

A

MIL-W-5086A - uses a tin-coated copper conductor rated at 600 volts and temperatures of 105 degrees Celcius - then coated with various insulating coatings

47
Q

What is the standard wire used in commercial and military aircraft?

A

use wire manufactured under MIL-W-22759 - which complies with military and FAA requirements

48
Q

What is the most important consideration in the selection of aircraft wire?

A

matching the wire’s construction to the application environment

ADDITIONAL INFO:
a) wires are typically categorized as being
suitable for either open wiring or protecting
wiring systems

b) wire temperature rating is a measure of the
insulation’s ability to withstand the
combination of ambient temperature and
current-related conductor temperature rise

49
Q

What is a conductor?

A

a material that allows electrons to move freely from one atom to another within the material

50
Q

What are the 2 most commonly used conductors?

A
  1. copper
  2. aluminum
51
Q

What are the advantages and disadvantages of using Copper as a conductor?

A

ADVANTAGES:
1. has a higher conductivity
2. it is more ductile
3. has relatively high tensile strength
4. can be easily soldered
DISADVANTAGES:
1. more expensive than aluminum
2. heavier than aluminum

52
Q

What are the advantages and disadvantages of using Aluminum as a conductor?

A

ADVANTAGES:
1. lightness makes possible long spans
2. large diameter reduces corona
DISADVANTAGES:
1. has only about 60% of the conductivity of
copper

NOTE: Copper is used extensively

53
Q

Plating
What is it?
Why is it done?

A
  1. Bare copper develops a surface oxide coating,
    which is a poor conductor of electricity
  2. So, all aircraft wiring has a coating of tin,
    silver, or nickel that have slower oxidation
    rates
54
Q

Describe Tin-coated copper plating

A
  1. a very common plating material
  2. can be successfully soldered without highly
    active fluxes
  3. can be used up to the limiting temperature of
    150 degrees Celcius
55
Q

Describe Silver coated plating

A
  1. used where temperatures do not exceed 200
    degrees C (392 degrees F)
56
Q

Describe Nickel-coated plating

A
  1. nickel coated wire retains its properties up to
    260 degrees Celcius
  2. soldered terminations require the use of
    different solder sleeves and or flux other than
    those used with tin or silver plated conductor
57
Q

What are the two fundamental properties of insulation materials?

A
  1. insulation resistance
  2. dielectric strength
58
Q

Describe insulation resistance

A
  1. the resistance to current leakage through and
    over the surface of insulation materials
  2. can be measured with a
    megohmmeter/insulation tester
  3. data obtained this way may not show the true
    condition of the insulation
  4. clean, dry insulation with cracks or other
    faults might show a high value of insulation
    resistance, but would not be suitable for use
59
Q

Describe Dielectric strength

A
  1. the ability of the insulator to withstand
    potential difference
  2. usually expressed in terms of the voltage at
    which the insulation fails because of the
    electrostatic stress
  3. maximum dielectric strength values can be
    measured by raising the voltage of a test
    sample until the insulation breaks down
60
Q

What characteristics are considered when choosing conductor insulation material?

A

Characteristics should be based on environment, such as:
1. abrasion resistance
2. arc resistance
3. corrosion resistance
4. cut-through strength
5. dielectric strength
6. flame resistant
7. mechanical strength
8. smoke emission
9. fluid resistance
10. heat distortion

61
Q

What types of insulation materials are no longer used in aircraft?

A
  1. PVC/Nylon
  2. Kapton
  3. Teflon

can still be found on older aircraft

62
Q

Describe wire shielding

A
  1. the process of applying a metallic covering to
    wiring and equipment to eliminate
    electromagnetic interference (EMI)
63
Q

What caused Electromagnetic Interference (EMI)?

A

EMI is caused when electromagnetic fields (radio waves) induce high frequency (HF) voltages in a wire or component

64
Q

Wire Size Selection - Things to know

A
  1. wire is manufactured in sizes according to a
    standard known as the American wire gauge
    (AWG)
  2. wire diameter becomes smaller as the gauge
    number becomes larger
  3. typical wire sizes range from 40 to 0000
65
Q

Wire Sizes - Things to know
** Go over Pg 9-69 in Vol 1

A
  1. wires containing less than 19 strands must
    not be used
  2. use high strength alloy conductors in small
    gauge wires to increase mechanical strength
  3. wires smaller than #20 should be provided
    with additional clamps and grouped with at
    least 3 wires. Should also have additional
    support at terminations (connector grommets,
    strain relief clamps, shrinkable sleeving, or
    telescoping bushings)
  4. insulated conductor does not easily dissipate
    heat - too protect the insulation from too
    much heat, the current through the conductor
    must be maintained below a certain value -
    allowance must be made for the influence of
    external heating on the allowable conductor
    current
66
Q

What is the maximum allowable operating temperature of insulated conductors?

A

the maximum allowable operating temperature of insulated conductors varies with the type of conductor insulation being used

67
Q

Current Carrying Capacity - Things to Know

A
  1. in some cases, the wire may be capable of
    carrying more current than is recommended
    for the contacts of the related connector - in
    this case, it is the contact rating that dictates
    the maximum current to be carried by a wire
  2. wires of larger gauge may need to be used to
    fit within the crimp range of connector
    contacts - this gives a family of curves
    whereby the bundle derating factor may be
    obtained
  3. first must determine the maximum current
    that a given sized wire can carry without
    exceeding the allowable temperature
    difference
68
Q

Describe the maximum operating temperature

A
  1. rated temperature may be based on the
    ability of either the conductor or the insulation
    to withstand continuous operation without
    degradation
69
Q

Describe Single Wire in Free Air

A
  1. first must determine the maximum current
    that a given sized wire can carry without
    exceeding the allowable temperature
    difference
  2. The curves are based upon a single copper
    wire in free air
70
Q

Describe Wires in a Harness

A
  1. when wires are bundled into harnesses, the
    current derived for a single wire must be
    reduced
  2. the amount of current derating is a function of
    the number of wires in the bundle and the
    percentage of the total wire bundle capacity
    that is being used
71
Q

Describe Harness at Altitude

A
  1. since heat loss from the bundle is reduced
    with increased altitude, the amount of current
    should be derated
  2. This gives a curve whereby the altitude-
    derating factor may be obtained
72
Q

Describe Aluminum Conductor Wires

A
  1. sizes should be selected on the basis of
    current ratings
  2. the use of sizes smaller than #8 is
    discouraged
  3. termination hardware specifically designed for
    use with aluminum conductor wiring should
    be used
    WHEN NOT TO USE ALUMINUM WIRE
  4. aluminum wire should not be attached to
    engine mounted accessories
  5. aluminum wire should not be used in areas
    having corrosive fumes, severe vibration,
    mechanical stresses or where frequent
    disconnection is needed
  6. do not use aluminum wire for runs less than 3
    feet
73
Q

Computing Current Carrying Capacity

A

See Volume 1 - Pgs 9-71 - 9-75
there are 2 examples of how this is computed

74
Q

Allowable Voltage Drop = Things to know

A
  1. the voltage drop in the main power wires
    from the generation source or the battery to
    the bus should not exceed 2 percent of the
    regulated voltage when the generator is
    carrying rated current or the battery is being
    discharged at the 5-minute rate
  2. when checking a circuit, the input voltage
    should be maintained at a constant value
75
Q

What is the formula used to check voltage drop?

A

VD = resistance/ft x length x current

VD = voltage drop

76
Q

What 2 major requirements must be met when selecting the correct size of electrical wire?

A
  1. the wire size should be sufficient to prevent
    an excessive voltage drop while carrying the
    required current over the required distance.
  2. the size should be sufficient to prevent
    overheating of the wire carrying the required
    current
77
Q
A
78
Q

What information must be known in order to select the correct size electrical wire?
Hint: there are 7

A
  1. the wire length in feet
  2. the number of amperes of current to be
    carried
  3. The allowable voltage drop permitted
  4. the required continuous or intermittent
    current
  5. the estimated or measured conductor
    temperature
  6. is the wire to be installed in conduit and/or
    bundle?
  7. is the wire to be installed as a single wire in
    free air?
79
Q

Describe the placement of identification markings on electrical wires

A
  1. ID markings should be placed
    a. at each end of the wire and
    b. at 15 inch maximum intervals along the
    length
  2. wires less than 3 inches do not need to be
    identified
  3. wires 3-7 inches should be identified in center
    of the wire
80
Q

What are the 2 methods of marking wire or cable?

A
  1. Direct Marking
  2. Indirect Marking
81
Q

Describe Direct Marking
See Vol 1 - Pg 9-77 for picture)

A

accomplished by printing the cable’s outer covering

82
Q

Describe Indirect Marking
(See Vol 1 - Pg 9-77 for picture)

A
  1. accomplished by printing a heat-shrinkable
    sleeve and installing the printed sleeve on the
    wire or cables outer covering.
  2. indirectly marked wire and cable should be
    identified with printed sleeves at each end at
    intervals not longer than 6 feet.
  3. the individual wires inside a cable should be
    identified within 3 inches of their termination
83
Q

What methods are used for mark directly on the wire?

A
  1. hot stamp marking
    a. can damage insulation of newer types of
    wire using thin insulators - can cause arcing
  2. ink jet printers
  3. laser jet printers
84
Q

Identification sleeves are normally used for identifying which types of wire and cable?

A
  1. unjacketed shielded wire
  2. thermocouple wire
  3. coaxial cable
  4. multiconductor cable
  5. high temperature wire
85
Q

Identification Sleeves - Additional Things to Know

A
  1. for sleeving exposed to temp over 400
    degrees F - materials such as silicone
    fiberglass should be used
  2. Polyolefin sleeving should be used in areas
    where resistance to solvent and synthetic
    hydraulic fluids is necessary
  3. in most cases, identification tape can be used
    in place of sleeving
86
Q

What is open wiring?

A
  1. electrical wire installed in aircraft without
    special enclosing means
87
Q

What is the advantage of open wiring?

A

ease of maintenance and reduced weight

88
Q

Describe a wire harness

A
  1. wire are often installed in bundles
  2. wire bundles are called wire harnesses
  3. often made in the factory on a jig board so
    wire bundles could be preformed to fit into
    the aircraft, so each harness for a particular
    aircraft installation is identical in shape and
    length
  4. wire harness can be covered by a shielding
    (metal braid) to avoid EMI.
  5. don’t group/bundle electrically unprotected
    wiring
  6. wire bundles should be less than 75 wires or 1
    1/2 - 2 inches in diameter
89
Q

Why should wiring be installed with sufficient slack?

A

So that the bundles and individual wires are not under tension

90
Q

Give 3 examples when parallel wires must be twisted

A
  1. wiring in the vicinity of magnetic compass or
    flux valve
  2. three-phase distribution wiring
  3. certain other wires (usually radio wiring) as
    specified on engineering drawings
91
Q

Spliced Connections in Wire Bundles -
Things to know

A
  1. splicing of power wires, coaxial cables,
    multiplex bus, and large gauge wire must have
    approved data
  2. splicing of electrical wire should be kept to a
    minimum
  3. splicing of electrical wire should be avoided in
    locations subject to extreme vibrations
  4. splicing of individual wires in a group/bundle
    should have engineering approval and splices
    should be located to allow periodic
    maintenance
  5. splicing individual wires - use a self insulated
    splice connector
  6. splicing in swamp areas - use environmentally
    sealed splices that conform with MIL-T-7928
  7. there should be no more than one splice in
    any one wire segment between 2 connectors
  8. splices in bundles must be staggered
92
Q

When is splicing wire permitted?

A

as long as it does not affect the reliability and the electromechanical characteristics of the wiring

93
Q

As a rule there should only be one splice in any one wire segment between 2 connectors - what are the exceptions to this rule?

A
  1. when attaching to the spare pigtail lead of a
    potted connector
  2. when splicing multiple wires to a single wire
  3. when adjusting wire size to fit connector
    contact crimp barrel size
  4. when required to make an approved repair
94
Q

The minimum radius of bends in wire groups/bundles must not be less than?

A

10 times the outside diameter of the largest wire or cable

Note: where the wire is suitably supported - the radius may be 3 times the diameter of the wire or cable.

95
Q

RF cables (coaxial and triaxial) are bent at a radius of ?

A

No less than 6 times the outside diameter of the cable.

96
Q

Wiring - Protection Against High Temperature
- Things to Know

A
  1. wiring must be routed away from high
    temperature equipment and lines to prevent
    deterioration of insulation
  2. wires must be rated so the conductor
    temperature remains within the wire
    specification max
  3. separate wires from high temperature
    equipment, such as resistors, exhaust stacks,
    and heating ducts to prevent insulation
    breakdown
  4. don’t use cables with soft plastic insulation,
    such as polyethylene in high temperature
    areas as these materials are subject to
    deterioration and deformation at elevated
    temperatures
97
Q

Wiring - Protection Against Solvents and Fluids
- Things to Know

A
  1. must separate wire and lines from equipment
    containing oxygen, oil, fuel, hydraulic fluid, or
    alcohol
  2. wiring must be routed above these lines and
    equipment with a minimum separation of 6
    inches or more
98
Q

What is a drip loop?

A
  1. an area where the wire(s) are made to travel
    downward and then up to the connector
  2. fluids and moisture will flow along the wires to
    the bottom of the loop and be trapped there
    to drip or evaporate without affecting
    electrical conductivity in the wire, junction, or
    connected device
99
Q

Protection of Wires in Wheel Well Areas
- Things to Know

A
  1. wires located on landing gear and in the wheel
    well area can be exposed to many hazardous
    conditions
  2. wiring and protective tubing must be
    inspected frequently
  3. replace wiring at first sign of wear
  4. wires should be routed so that fluid flows
    away from the connectors
  5. wiring in wheel wells are other external areas
    must be given extra protection in the form of
    harness jacketing and connector strain relief
  6. conduits or flexible sleeving used to protect
    wiring must be equipped with drain holes
100
Q
A

Airframe Test (11 decks)

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