Module 7.7 Flashcards
what is continuity testing ?
checking that an electrical system is connected and servicable
when continuity testing why must the power be off?
damage can be caused when measuring the system or to the multimeter or aircraft system.
what should the meter be set to if the resistance is unknown?
highest setting then work down
what will a multimeter need in an open circuit?
1 or 1/2
Ain’t got a scooby
what must be known on a continuity test?
the expected reading
what should be done with parallel components?
isolate them
what should be done before a continuity test?
visual inspection
what two parts of info does a continuity test provide?
that there is an electrical link and the resistance of said link
on an aircraft, how could continuity test be conducted?
connecting to the airframe structure
on an analogue multimeter, what do they not require?
no battery, ohm requires it
why does a megger have a higher voltage than the system?
test at 3x the working voltage
what should be done to an LRU before insulation tests?
disconnect to the LRU
what does good bonding allow?
safe path for current flow
what resistance should a bonding check produce?
less than 0.05 ohm for primary, 0.02 ohm for comms and nav
what does bonding protect from?
static build up
what does good bonding allow?
ensures safety of aircraft and occupants
where would the master point be?
avionics bay. one for AC one for DC
where would dual grounding cables be used and why?
fuel tanks for resistance
what must never be done after stripping a wire?
touching it with your fingers
what are the most common types of electrical tooling?
Daniels(pins and sockets) and AMP/PIDG
how can a crimp be checked?
go/no go gauges
where would all standard electrical practices be found?
chapter 20
how long should the wire be stripped for the PIDG crimp?
half the barrel + 1/32
how much wire should protude from a crimp and why?
1/32
daniels tools produce an 8 compression crimp. what does this ensure?
maximum tensile strength
how much gap should the insulation and the barrel have?
1/32’’
what are the benefits of crimps?
-good conductivity
-uniformity of connection
-strength of connection
- corrosion proof
what is a way of checking the tool has crimped correctly?
Dot code
how are crimp tools distinguished?
colour of the handles
what is the purpose of the insulation adjusting pins?
change how tight the grip is around the insulation
what gauge of wire would you use a hydraulic crimping tool?
2 to 8 gauge
what is the main difference between hydraulic and normal crimp?
hydraulic not latched, so it can be released during crimping (safety feature)
what occurs when a hydraulic tool reaches the correct PSI?
it will release at roughly 2000 PSI
how is an electrical crimping tool activated?
trigger or foot pedal
how are crimp tools tested?
tensile test or pull test
what will occur if the crimp is correct?
the cable will snap before the crimp fails
what is the volt drop test?
pass current through and measure the drop between part A and part B. Making sure that the drop is in allowance limits
what colour is the extraction tool for rear release?
white
what are copper losses?
loss due to internal resistance
what are electrical losses?
losses due to heating
where are coax cables grounded?
grounded at both ends
what are the differences between BNC and TNC?
TNC are threaded
how can coax cables be tested?
continuity test e.c.t
what does a TDR do?
tells how far along damage inside the cable is
what do the last two digits of code on a cable signify?
wire gauge
what amount of strands are cables typically made up of?
7 or 19
when would aluminium be used in wires?
on cables with large current along a long distance
where are interconnect cables used?
interconnecting of equipment in racks
how long should a fire resistant cable last under a fire environment?
5 mins
where is an equipment cable used?
inside LRU’s and should not be touched
what can be said about the insulation on thin walled cables?
thinner and high spec insulation
how long should a fireproof cable last under a fire environment?
15 mins
how do twisted cables minimise magnetic inteference?
they cancel each other out
power feed cables are what gauge?
2 to 8
what will happen to a coax if the bend radius is not adhered to?
the dielectric will be damaged
conduits have what at the bottom to allow for drainage?
a hole
when passing through a bulk-head what is required?
a grommet plus P clips to secure
what must cable breakouts not do?
must not cross over the loom
what should you secure coax with?
don’t tie
what should be done to secure in high voltage areas
P clamps are the most common method
where should looms be ran in relation to piping?
looms should be above piping
what heating tool can be used on an aircraft?
hot air gun
what are the three types of inspection?
-general vision inspections
-detailed inspections
-zonal inspections
what can be used to aid in a GVI?
mirror, torch, magnifying glass ect
what does dust not allow?
heat disapation
what should be done to splices in the same area?
staggered
detailed inspections take place more often in what environment?
high vibration
when cleaning a cloth to clean looms, what must it be?
clean, dry and lint free.
