7.7 Electrical Wiring Interconnection System (EWIS) Flashcards by Meg Bazeley

What 3 things should installation of wires conform to

1st is safety
2nd is ease of maintenance
3rd is cost effectiveness

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Where must plastic ties not be used

In unpressurised areas

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What minimum distance must be maintained with wire bundles from pipes carrying flammable liquids?
What distance from pipes that are not carrying anything harmful?

50mm from harmful
15mm from not harmful

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What’s the minimum bend radius for single wires and what’s the preferred bend radius

Minimum is 3 times the outside diameter of the wire and the preferred is 10 times the outside diameter of the wire

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What’s the minimum bend radius for a wire BUNDLE

6 times the outside diameter

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What’s the minimum bend radius of a coax cable

10 times the outside diameter

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How’s a wire checked to see if it’s been installed correctly into a connector

By tugging on it slightly

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What should be carried out each time a connected is disconnected and reconnected

A functional test and a visual check of connector

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Why’s is important to leave some slack before terminating a wire at a connector

to facilitate connector removal/replacement

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What’s a drip loop and why are they carried out

A drip low is a downwards loop that’s provided to allow any moisture to drip off at a low point on the wire instead of dripping into a connector or plug

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What’s important to remember about wires in a conduit

Not to be tied and must have a draw wire installed

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At what point should drainage holes be fitted in conduits

At the lowest point

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How’s a over braid shield identified

With a W number

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What’s an AP wire and under what conditions are they aloud to be fitted

Aromatic polyamide and they’re not aloud to be fitted to the aircraft and are only aloud on the aircraft if they was there on manufacturing

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What’s important that’s done with wires to ensure they’re protected

They’re separated to ensure that if one fails that they don’t fail together

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What are the dangers present with electricity?

Electric shocks
Burns
Fire
Explosion

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Why are drip loops installed

To prevent fluid contamination

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Why are drip loops installed

To prevent fluid contamination

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What are the 3 types of separation

Separation between power sources
Separation between redundant system circuits
Separations between emc circuits that aren’t compatible

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How are electrical circuits which are necessary for wire separation separated?
If the solution isn’t available what can be done?

They should be put into separate harnesses and if not achievable they’re put in the same one but with sleeves and shielded wire

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What are the six groups wires are grouped into?
It’s fucking aids but the old man said to remember

G-Generation
P-Powerdistribution
M-Miscellaneouscables
S-Sensitivecables
R-Audiocables
T/U/V-Coaxialcables

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When preparing to work on de-energised circuits ensure what?

-The external power is switched off
-The battery is disconnected
-Red safety tags are fitted

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What intervals are clamps placed at

Every 24 inches

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What does the damage out of voltage and amps?

Amps

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Where must rubber fillers not be used

In clamps carrying Coax cables

In what areas should you never use electric tools that deliver more than 0.02 millijoules of energy?

Fuel tanks or flammable vapour areas

What temperatures must plastic clamps not exceed

250 FAHRENHEIT (121 Celsius)

Where can metal clamps be used

Anywhere as long as the correct insulation is used

What must insulating tape be used on and why

AP wires to prevent damaging the insulation

If nylon clamps use a spacer what must also be fitted and what effect does this have on the use ability of it?

A washer ans can’t be used in fuel tanks in case they come loose

When would a suitable grommet be required to be fitted when wires are passing through a hole

If the gap between the wires and the hole is less than 1/4 of an inch

How can separation of wires also be achieved?

By clamping to structural tubing (not on tubing carrying anything)

How far must wire be separated from hot air ducts for airbus and Boeing

50mm airbus 1 inch for Boeing

What’s Boeings spacing requirements

That they must keep a minimum distance of 2 inches from fuel lines, hydraulic fluid lines, oxygen lines, control cables

What’s the preferred installation method of wire clamps

With the back resting On a structure and with the mounting screw Sitting above the wire

What tapes used for creating a sealant mould

Paper and vinyl tape Paper must be fitted with a string to remove the tape after the sealants cured

What’s used to fill the gaps between wires and cables

Using coils and star spacers

Why are wire bundles tied

To provide ease of installation, maintenance and inspection

What material is used for tying and what one requires to be waxed

Cotton, nylon and fibreglass Cotton is waxed ans us done to prevent moisture and mold

Where must ties not be used

In fuel tanks

At what intervals would ties be placed in normal conditions and in high vibration

They’d be positioned every 8 inches Positioned every 2 in high vibration areas

What can be done to prevent wire group breakouts or to protect wires

Installing additional wires with sleeving

What are not allowed in unpressurised areas?

Plastic ties

Wire bundles in the fuselage must be clamped when?

At every frame

What size wires are plastic ties not aloud to be used on

Wires bigger than 10 awg

What’s preferred, wire replacement or splicing

Replacement

What’s the maximum amount of splices aloud per wire

3 other than the wires stated in production

What’s important to remember about positioning of splices

They must be staggered

What’s an indication of heat damage on a wire

Change in colour

How many wire splices may be done in one section

No more than 2 per section

Where can’t splices be used

In fuel tanks In conduits In clamps Within 12 inches of termination device In harnesses that are frequently bent

What cables are not permitted for repair due to there critical impedance

Low range altimeters Guide slope Coax cable that’s already repaired

What causes a high proportion of aircraft failures

Poor connections

What’s a superchamp used for and what’s it’s not aloud to be used on

Used for stripping wire ans forbidden on crimping

What determines whether to install pins or sockets at a connector

By establishing which side of the disconnect is live or hot

What are the two general groups of connectors

Split shell and assembled

What are the 5 groups of AN connector and what are they made from

A,B,C,D,K A,B,C,D are aluminium K is steel which makes it fireproof

What’s the most common connector type

Assembled

What’s the additional aid given for number contact configurations to aid in counting correctly

Every 10th contact is circled

What are the order in which letters are used for indemnifying contact holes in a connector

Upper case Then lower case Then double uppercase letter

Where do letter contact configuration start

Start outside finish inside

What must be done to unused contact holes

They must be fitted with Teflon or nylon seal plugs

What are coaxial cables used for

Interconnecting the components in the circuits transporting high frequencies

What are polarisation keys used for

To prevent the wrong computer being fitted into the wrong shelf

What does the keying code on the polarisation key also form

The last two digits on the connnector part number

What’s soft solder made from

Tin lead alloy

What’s soft solder used for

Electrical applications

What’s silver solder made up from

Silver solder

What’s the purpose of a flux

To remove the oxide from the surface being soldered to provide a good flow of solder into the joint

What can happen if the connector is moved around while the solders setting

It can lead to a poor dry joint

What does PIDG stand for

Pre insulated diamond grip

How many unstripped wires are aloud per end cap

Only one

What does CAU stand for

Circular area unit

How is conductor crimp and barrel compatibility determined

Based on CAU

How are phase a,b and c identification sleeves identified

A red B yellow C blue

What’s the maximum number of terminals per stud

What’s the maximum amount uninsulated and insulated terminals can be bent in restricted places? And for installation on a terminal block?

90 degrees in a restricted place 30 degrees on a terminal block

How many times can a terminal be bent

1 time

How many contacts can a terminal module accommodate

10 or twenty one contacts

What’s bonding

process of obtaining the necessary electrical conductivity between the component metallic parts of the aircraft.

Why must non conducting paints and anodising films be removed prior to bonding

TO ensure a low resistance for bonding leads

How many grounds must be installed in fuel vapour areas

Two

As a general rule what should the resistance values be for grounding

0.0025

What are the usual voltages used for testing insulation

250 or 500V

When should insulation testing only be carried out

When the wires disconnected from there system at both ends

What machines used to test continuity

Ohmmeter and multimeter

When must continuity tests only be carried out

On circuits with no power applied

What’s used to test coax cable

TDR (time domain reflectometry

What’s Boeing use for there wiring manual

Swpm

What’s airbus use as there waiting manual

Espm

What’s a GVI

General visual inspection and it’s done at touching distance unless specified

What’s a DET

detailed inspection that allows tactile examination to determine condition

What are the 3 vibration levels

1 = not high vibration 2 & 3 are high vibration

What’s a SWAMP area

Severe weather and moisture prone

Why is it important to clean up swarf and dust

Because they are flame catalysts

What’s required to ensure electrical equipment stays in good condition

An annual clean up

Why’s cleaning of electrical equipment important

As damage may also be detected during the process

What are the three types of contamination

Fluid Environmental Solid

What are conduits 2 subgroups

Open and closed conduits

What are regulations must be followedwith conduits

No ties A drainage hole must be installed at the lowest point A draw/pull wire must be installed

What knot do we do

Clove hitch and square knot