Under what condition is the resistance of the current return path through an aircraft considered negligible?

The resistance of the current return path through an aircraft is considered negligible when the structure is adequately bonded. Adequate bonding ensures that there is a low-resistance electrical connection between various parts of the aircraft structure, allowing electrical currents to flow freely without significant loss or interference. This is crucial for ensuring the proper operation of electrical systems and for maintaining safety, as it helps prevent issues such as electromagnetic interference and ensures that the return path for electrical currents is stable and reliable.

Bonding is typically accomplished through the use of conductive materials and techniques that connect differing parts of the structure, such as wings, fuselage, and control surfaces. When bonding is effective, it minimizes the electrical resistance between the components, allowing the current to return through the structure with minimal energy loss. In contrast, if the structure is not adequately bonded or is painted (which can insulate surfaces and increase resistance), the return path might not provide the necessary performance. Therefore, bonding is a critical factor in ensuring the integrity of current return paths in aircraft electrical systems.