questions 2 Flashcards
what do the initials PIDG stand for?
pre insulated diamond grip
when checking the insulation group using the AMP crimping tool, what position number should you start from?
position 3
prior to using a PTT, what must the tool be subject to?
- calibration check
- ratchet check
- go/no-go check
- insulation adjustment
crimping a red AMP crimp, how many dots/lines should be visible on the crimp?
one dot, two lines
moving a hydraulic crimping tool, what gives an indication that the dies have bottomed?
- internal bypass valve opens, reducing pressure
- dies should not accept 0.001” shim
what procedure should be used when crimping multi-contact connectors if some of the contact positions are not used?
blanked off using appropriate blanking plugs
what is eyeball crimping?
- not recommended
- contact inserted from underside with barrel facing operator
- align pot with inventors, clamp but do not crimp
- insert prepared conductor from rear and crimp
on a cable loom that has solder sleeves, what is the stagger distance for the sleeves?
between 4-6 inches from plug or receptacle
on a solder sleeve, what size cable is normally used for the tail?
22AWG
state the composition of soft solder
60% tin, 40% lead
explain the general purpose of heat sinks
- prevents heat sensitive components from being damaged
explain the difference between activated and non activated fluxes and other general areas of use
active fluxes contain active agents, used where more active cleaning agents are necessary
state and describe the difference between soft soldering and brazing
brazing performed at much higher temperatures
what factors should cables be protected against?
- mechanical damage
- damage from fluids/vapours
- heat damage
- sharp bends
what is the general rule (moisture) with regards to routing of cables to LRU’s?
ensure cables run downwards from component
what are the methods used for cable bending and support?
- wax string
- p-clips
- tie-wraps
- looming cord
what factors dictate the composition of a cable loom?
- overall diameter
- temperature conditions
- type of current
- type of system
which areas would you normally use conduit for conveying cables?
where possibility of exposure to fuel/hydraulic oil/ other harmful fluids
using a metal conduit in place of a plastic conduit, what additional task needs to be carried out and why?
conduit needs to be bonded to airframe (signal interference)
in a pressure bung, and several cables were no longer required, what procedure would you carry out?
cut cable 6-9” either side of bing and fir 3/4-1” plain sleeves at each end
what test needs to be carried out after the final installation of a cable pressure seal?
pressure test
in a ducted loom, how are the specific consumer systems identified?
appropriately coloured wax wiring/string
on a pressure bung that is having wires inserted, what is the general rule?
pull wires to desired length before removing tool
what is the purpose of bonding?
joining two or more conducting objects in such a way that an electrical current may flow easily from one to the other
define primary and secondary conductors and the sizes normally used
- primary conductors carry lightning strikes - 3/6mm squared
- secondary conductors - all other forms of bonding - 1mmsquared
where would you find a sacrificial plate?
between two dissimilar metals
what is the term inherent bonding?
adequate electrical path between parts and assemblies without any special action
how does a ground discharge method work?
- through nose wheel tire impregnated with electrically conducting compound or static discharge whip trailed from landing wheel assy
what are periodic inspections of bonding and earth assemblies carried out for?
signs of
- overheating
- corrosion
- resistance checks
what are the two testers used to measure bonding resistance?
- 250V insulation tester
- the bonding tester
which organisation states the maximum resistance values for primary bonding between extremities of the fixed portions of aircraft of non metallic or composite contstruction?
the CAA
what test should be carried out on earth terminal assemblies that are also used to carry electrical supplies?
millivolt drop test
when heat shrinking, where should the heat be applied to first?
centre of heat shrink, working outwards
what is the normal curing time for adhesive type s1006?
24H at room temp, 2-4 days for max strength
what psi air supply is required in a raychem thermopistol?
50psi
how long should you leave a raychem thermopistol to stabilise the temperature and also the time to elapse before disconnecting the air supply on completion?
- 15 min to stabilise
- 5 min before disconnecting
when a potting connector becomes unserviceable, what should it be replaced with?
one of the new EP connectors
what are the forces that exist in a basic meter movement?
- deflecting force (current in the coil)
- controlling force (spring strength)
- damping force (prevents hunting)
in older meters, how was hunting of the needle eliminated?
a small air dashpot connected to the movement
state the two types of meters
- moving iron
- moving coil
what principle do meters operate on?
motor principle, i.e. magnetic repulsion
what material are shunts used in current meters made from?
manganin
what principle is used in meters that measure resistance?
- measure the current flow through an unknown resistor
- instrument movement as a DC ammeter
- internal dry battery as a voltage source
what value would you expect to find on a perfect insulator using a megger?
infinity
what are the advantages and disadvantages of a moving coil meter?
advantage
- measures current and voltage
disadvantage
- cannot be used on AC
what is the main advantage of a moving iron type meter?
advantages
- cheap
- used on AC and DC
what aircraft systems would you not use a bonding tester on?
explosive or pyrotechnic systems (1A current more than 10mA required to set off)
what effect does power variations have on a ratiometer system?
accurate over small variations in supply voltage
state the general use of a clamp meter and its general description of operation
- measures current through enclosing
- transformer principle
on an oscilloscope waveform with a period of 4ms, calculate the frequency
- 1/time period
- 250Hz
state the correct sequence to carry out inspections on an aircraft
- Visual (very)
- Bonding (big)
- Continuity testing (cow)
- Insulation resistance check (in)
- Functional (field)
what equipment would be used to determine if a coaxial cable has insulation resistance damage?
time domain reflectometer
if modifications or repairs have been carried out in the vicinity of looms, what additional inspections/checks are carried out?
inspection for swarf/tooling/damage to wires in vicinity
using a bonding tester, which lead is connected first and why?
connect probe B first. then A. risk of damage otherwise
what test would be carried out on cables that have been stamped?
british standard test 16
how can the accuracy of a bonding tester be determined?
- checked periodically by measuring resistance of standard test resistors
- should be within 10% of resistor value
what methods could be used to carry out a continuity check?
- end to end
- short between two cables
- use aircraft structure
what specification is used to standardise documentation?
ATA 100
which manual shows a picture of aircraft components and gives the part number?
illustrated parts catalogue
which manual supplies information on aircraft wiring configuration?
wiring diagram manual
what are the two types of wiring diagram?
- schematic
- wiring diagram
how is the typical numbering system of chapters known?
- 24-20-14
- chapter
- sub-system
- unit/system
