Grounding and Bonding in Aircraft

TROUBLESHOOTING of Grounding and Bonding ISSUES: Visual Inspection: Visual inspection is the initial step in troubleshooting grounding and bonding issues. It involves inspecting bonding connec- tions, grounding conductors, and bonding points for physi- cal damage, loose connections, corrosion, or improper instal- lations. Visual inspection can often provide clues about potential issues that require further investigation.

Fault Isolation: If a grounding or bonding issue is suspected, fault isolation techniques are employed to identify the specific location or component causing the problem. This may involve selectively isolating or discon- necting different parts of the grounding or bonding system and performing resistance tests to identify the faulty component. Resistance Testing: Loop and joint resistance measure- ments are commonly used during troubleshooting to identify high-resistance or open-circuit conditions in bonding conductors or ground- ing connections. By measuring

the end-to-end resistance of flexible bond joints, devia- tions from expected values can indicate potential issues that require immediate maintenance. Effective loop, grounding, and bonding test procedures and troubleshooting techniques are essential for maintaining the integrity and functionality of aircraft electrical systems. These practices help ensure compliance with regula- tory requirements, identify and rectify potential issues, and guarantee the safety and reliability of the aircraft’s electrical infrastructure.

GROUNDING on Earth and in Flight

The ground system and Faraday cage/shield of an aircraft is designed to equalize electrical potential and provide a path to “ground” for electrical surges or spikes impacting aircraft during refuelling and other Turn-Around-Time activities on the ground. But what about when the aircraft is in flight? How does this same system help to protect the aircraft’s electrical systems, equipment, and occupants from electrical faults, surges, and potentially damaging lightning strikes without direct contact to the earth? During flight, the aircraft’s grounding system does not rely on a direct connection to the Earth as it does during Turn-Around-Time operations. Instead, it utilizes the low-resistance, conductive skin of the aircraft, augmented with lightning protection system components (arrestors, conductive strips, ground straps, and so on) to channel the discharge to aircraft extremities where it may be returned harmlessly to the atmosphere. Static wicks (see sidebar) aid in the safe discharge of both static electricity as well as these higher-power electrical currents.

QwikConnect • July 2023


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