7.7 ( EWIS ) Flashcards
What is continuity testing ?
Testing a cable is serviceable
Before undergoing a continuity test,what should be done to The circuit ?
Disconnect battery
( if not, the power can damage test equipment )
Whats used to carry out a continuity test ?
Multi-meter
What must multi-meter be set to for a continuity test ?
Ohms range
( device should beep )
What is the two pieces of information a continuity test provides ?
- That there is an electrical link between two or more points on the circuit.
- That the resistance is within a specified value.
What will multi-meter read in an open circuit ?
1 or overload ( O/L )
What charge does an insulation have ?
Low current DC charge
What does an insulation test try and find ?
A current leak or damaged insulation.
what can damage to the insulator cause a wire to do ?
Cause it to short circuit
What is carried out before an insulator test ?
Visual, bonding and continuity test.
What does an insulator tester consist of ?
- Pointer
- Hand driven generator
- Connecting leads
Whats a bonding test used for ?
To see if all components, modules or LRU fitting on aircraft or circuit have the same potential to grounds.
What can good bonding prevent ?
Radio interference and induced noise.
What does bonding protect systems against ?
Build up of static discharge
What does good bonding ensure ?
- Safety of aircraft and its systems
- Minimises damage to structure
- Prevents passage of electrical currents which can cause dangerous malfunctions.
- prevents production of high potential differences within aircraft
What must be done to ensure a static charge doesn’t create a spark due to a difference in volts between two components ?
A conductive path must be provided to the earth.
What is grounding ?
Electrical connection of a conducting component to the primary structure for the return of current.
Where is the master grounding point on an aircraft ( where you take all readings ) ?
In avionics bay
Whats the three bonding techniques ?
- Equipment bonding
- Metallic surface bonding
- Static bonds
When bonding testing, what are you inspecting for ?
- Arcing
- Conduit bond
- Corrosion
- Free movement
Whats the 3 wire strippers ?
Single blade ( scalpel )
Double Blade.
Thermal
Most used crimping tools - M22520/2-01
AMP 59250 PIDG
What chapter is the ESPM ( Electrical service parts manual )
Chapt 20
Note : ESPM = AIRBUS
SWPM = BOEING
How much should b protruding out the end of a crimp ?
1/32 inch
How many indents does the two Daniel’s crimped put into the socket or pin ?
8 impressions
What must you check is on crimp tool before using it ?
Calibration tag
What does PIDG stand for ?
Pre insulated diamond grip
Whats the 4 advantages of using crimps ?
- Good conductivity
- Uniformity of operation
- Strength of connection
- Corrosion proof
How do you know if you have successfully crimped a PIDG terminal ?
Make sure crimp dots codes are visible on top of terminal and that wire strands are sticking out 1/32 inch.
How can you recognise which crimp tool to use ?
Colour coded handles on tool
Whats the purpose of an insulation adjusting pin ?
Allows various insulation diameters so it grips insulation well
When stripping a wire from crimping. How much insulation should you remove ?
Barrel length + 1/32 inch
What size gauge wires do you use a hydraulic crimp tool for ?
AWG - 2-8
( different dies can be fitted )
Does a hydraulic crimp tool have a release handle ?
Yes, release is on handle which you unthread.
What psi does a hydraulic crimp tool crimp to ?
2000 psi
How Can an electrical crimp machine be used ?
By hand or foot
( these also have release handles )
Whats the 3 ways you test a crimp tool ?
Visual inspection.
Tensile test or pull test
Volts drop test
Explain the tensile test or pull test on crimp ?
Crimp end onto wire with tool. Hang weight off of the crimped part to ensure its not to loose. If crimp stays on and secure, the crimp tool has passed.
Explain the voltage drop test on a crimp ?
Crimp wire with tool then send volts through end of cable and test how much volts comes out other end. If voltage drops to much IAW the max volts drop sheet then it’s failed.
What colour is the extraction side of rear release tool ?
White
Whats co-axial cables used for ?
Radio frequency’s
Is the co-axial cable grounded at both ends, one end or none ?
Both ends
Whats the two connectors found at the end of a co-axial cable ?
BNC - bayonet nut coupling
TNC - threaded nut coupling
Whats a TDR ?
Tester which tells you how far down any damage is on a wire.
What will the last two numbers on a cables surface tell you ?
Size / gauge of wire
How many strands does a small wire rang from ?
7-19
( larger wire has 19 or more )
What wire will you use where large amount of current must be carried for long distances ?
Aluminium wire
Where are airframe cables used ?
Where open airframe wiring is needed.
How long shall the insulation last on a fire resistant cable ?
5 minuets
How long shall the insulation last on a fire proof cable ?
15 minuets
What does a shielded cable stop from interfereing with the current ?
Stops magnetic field interfering
Whats hot stamping ?
Where a lazar prints the cable identification on insulation every 12-18 inches
Why is a hole drilled at the lowest point of a conduit ?
To allow moisture to exit
If you drill hole through bulkhead, what must be fitted ?
Grommet and p-clip clamp each side to hold in place.
Should you use tie straps on co-axial cables ?
No
What cable is used In LRUs ?
Interconnect cable
What is it called when two looms rub together and generate heat ?
Chafing
Whats the three types of EWIS inspections ?
General visual inspecion ( GVI )
Detailed inspection ( DET )
Zonal inspections
What can affect the heat disipotation of a wire ?
If dust builds up on surface.
How are splices placed to one another ?
Staggered
What must you use to clean dust or scarf off wires and cables ?
Lint-free cloth or vacuum
