7.7 Electrical Wiring Interconnection System (EWIS) Flashcards
What 3 things should installation of wires conform to
1st is safety
2nd is ease of maintenance
3rd is cost effectiveness
Where must plastic ties not be used
In unpressurised areas
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
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
What’s the minimum bend radius for a wire BUNDLE
6 times the outside diameter
What’s the minimum bend radius of a coax cable
10 times the outside diameter
How’s a wire checked to see if it’s been installed correctly into a connector
By tugging on it slightly
What should be carried out each time a connected is disconnected and reconnected
A functional test and a visual check of connector
Why’s is important to leave some slack before terminating a wire at a connector
to facilitate connector removal/replacement
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
What’s important to remember about wires in a conduit
Not to be tied and must have a draw wire installed
At what point should drainage holes be fitted in conduits
At the lowest point
How’s a over braid shield identified
With a W number
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
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
What are the dangers present with electricity?
Electric shocks
Burns
Fire
Explosion
Why are drip loops installed
To prevent fluid contamination
Why are drip loops installed
To prevent fluid contamination
What are the 3 types of separation
Separation between power sources
Separation between redundant system circuits
Separations between emc circuits that aren’t compatible
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
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
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
What intervals are clamps placed at
Every 24 inches
What does the damage out of voltage and amps?
Amps
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
4
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
