Aircraft Wiring Types and Installations
Modern aircraft wiring types rely heavily on having reliable electrical systems and subsystems for safe and effective operations. In turn, these systems rely on wiring that, if not properly installed, inspected, and maintained, can lead to potential and immediate danger to the aircraft.
At its most basic, a wire is a single, solid conductor, or a stranded conductor covered with an insulating material. Because of in-flight vibrations and flexing, most conductor wires should be round in shape. Cable is a term used in aircraft electrical installations to describe two or more separately insulated conductors in the same jacket, two or more separate conductors twisted together, one or more conductors covered with a metallic braided shield, or a single insulated center conductor with a metallic braided outer conductor.
The term “wire harness” is used to describe an array of insulated conductors bound together by lacing cord, metal bands, or other binding in an arrangement suitable for use in specific equipment in which the harness was designed, and can include terminations as well. Harness are frequently used in aircraft to connect electrical components.
The most common wire in light aircraft is MIL-W-5086A, a tin-coated copper conductor rated at 600 volts and temperatures of 105 degrees Celsius. Commercial and military aircraft use wire manufactured under MIL-W-22759 specification, compliant with current military and FAA requirements. The most critical factor for choosing wiring is matching the wire’s construction to the application environment. Wires are typically categorized as being suitable for either open wiring, or protected wiring applications. The wire temperature rating is a measure of the insulation’s ability to survive ambient temperatures and current-related temperatures.
Two important properties of insulation materials are insulation resistance, and dielectric strength. Insulation resistance is the resistance to current leakage through and over the surface of insulation materials, which can be measured with a megohmmeter/insulation meter. Dielectric strength is the ability of the insulator to withstand potential difference and is usually expressed in terms of voltage at which the insulation fails.
With more and more sensitive electronic devices being used in aircraft, proper shielding is essential. This involves applying a metallic covering to wiring and equipment to prevent electromagnetic interference, or EMI. EMI is caused by electromagnetic fields inducing high frequency voltages in wire and components, leading to system inaccuracies and failure.
Another consideration is SWAMP areas (Severe Wind And Moisture Problem). SWAMP areas, such as wheel wells, wing folds, pylons, and other exterior areas are subject to harsh environmental conditions, and wires in these areas require an exterior jacket to protect them.
At NSN Unlimited, owned and operated by ASAP Semiconductor, we can help you find all the electric wiring parts and systems for the aerospace, civil aviation, and defense industries. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at sales@nsnunlimited.com or call us at 1-480-504-1299.
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