Grounding and Bonding in Aircraft

Establishing Common Refer- ence Points: Bonding connects metallic components to a common electrical potential, minimizing resistance differ- ences between conductive components, and thereby reducing the generation of static electricity that may potentially ground to EWIS wiring in the form of EM or RF interference. Forming EMI Shielding Paths: Shielding techniques, such as EWIS cable screens and cable bay enclosures, create effective EMI shielding paths, which help direct and dissi- pate electromagnetic fields away from sensitive elec- tronic components, minimizing their impact. This is accom- plished by bonding these EWIS components to the MBN. Minimizing Ground Loops: Proper bonding techniques help prevent the formation of ground loops. By ensuring that interconnected components have low-resistance connec- tions to obtain near-perfect ground potential, bonding reduces the circulating currents

connections. These additional bonding components are used throughout the MBN, especially when connecting components are subject to conditions of high vibration or movement, such as in aircraft wings. Critical equipment such as sensors and communications antenna often employ both faying surfaces and auxiliary ground straps to ensure robust dissipation of electrostatic energy. The use of multiple bonding methods provides redundancy and helps maintain reliable electrical connections, essential for the proper func- tioning and safety of passengers as well as avionic and other mission-critical systems. Bonding and EMI Mitigation Electromagnetic interference (EMI) refers to the disturbance caused by unwanted elec- tromagnetic fields that can negatively impact the perfor- mance of electronic systems. Bonding in aircraft systems plays a vital role in mitigat- ing EMI in the following ways:

V 1

R 1

V 2

V out



I 1

Simplified circuit illustrating a ground loop

that can cause ground loops, further minimizing EMI risks. Electrostatic discharge: A final additional consideration in bonding’s role in EMI mitiga- tion is the facilitation of safe electrostatic discharge from aircraft wings and other extrem- ity surfaces which accumulate a buildup of static electricity from friction contact with air, rain, or dust. A static discharge system consisting of components known as static discharg- ers, or static wicks, is fitted in the trailing edges of the wings to discharge the buildup of static electricity on the airframe safely into the atmosphere (see sidebar for more information).

QwikConnect • July 2023


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