ELECTRICAL WIRING INTERCONNECTION SYSTEM (EWIS) Flashcards
An ____ is any wire, wiring device, or combination of these, including termination devices, installed in any area of the aircraft for the purpose of transmitting electrical energy between two or more intended termination points
EWIS
is the process of electrically connecting conductive objects to either a conductive structure or some other conductive return path for the purpose of safely completing either a normal or fault circuit
Grounding
_______ is the resistance to current leakage through and over the surface of insulation materials
Insulation resistance
________ can be measured with a megohmmeter insulation tester without damaging the insulation, and data so obtained serves as a useful guide in determining the general condition of the insulation
Insulation resistance
Mixing return currents from various sources should be _____ because noise is coupled from one source to another and can be a major problem for digital systems.
avoided
_______ is the electrical connecting of two or more conducting objects not otherwise adequately connected.
Bonding
______ low-impedance paths to aircraft structure are normally required for electronic equipment to provide radio frequency return circuits and for most electrical equipment to facilitate reduction in EMI. The cases of components that produce electromagnetic energy should be grounded to structure.
Equipment bonding
_______-—all conducting objects on the exterior of the airframe must be electrically connected to the airframe through mechanical joints, conductive hinges, or bond straps capable of conducting static charges and lightning strikes. Exceptions may be necessary for some objects, such as antenna elements, whose function requires them to be electrically isolated from the airframe. Such items should be provided with an alternative means to conduct static charges and/or lightning currents, as appropriate.
Metallic surface bonding
_______—all isolated conducting parts inside and outside the aircraft, having an area greater than 3 square inches and a linear dimension over 3 inches, that are subjected to appreciable electrostatic charging due to precipitation, fluid, or air in motion, should have a mechanically secure electrical connection to the aircraft structure of sufficient conductivity to dissipate possible static charges. A resistance of less than 1 ohm when clean and dry generally ensures such dissipation on larger objects. Higher resistances are permissible in connecting smaller objects to airframe structure
Static bonds
Testing of Bonds and Grounds
The resistance of all bond and ground connections should be tested after connections are made before re-finishing
The resistance of each connection should normally not exceed ________. A high quality test instrument, an AN/USM-21A or equivalent, is required to accurately measure the very low resistance values
0.003 ohm
Bonding jumpers should be made as ____1___, and installed in such a manner that the resistance of each connection does not exceed ____2___. The jumper should not interfere with the operation of movable aircraft elements, such as surface controls, nor should normal movement of these elements result in damage to the bonding jumper
- short as practicable
- .003 ohm
COPPER WIRE TERMINALS
Solderless crimp-style, copper wire, terminal lugs may be used which conform to MILT-7928. ______ should not be used between the tongues of terminal lugs.
Spacers or washers
The tongue of the aluminum terminal lugs, or the total number of tongues of aluminum terminal lugs when stacked, _______ when terminated on terminal studs.
should be sandwiched between two flat washers
Coaxial cables with _______ should not be used
solid center conductors
Identification markings should be placed ____1___ and at __2___ maximum intervals along the length of the wire.
- at each end of the wire
- 15-inch
