Which of the following is a common wiring fault seen in aircraft electrical systems?

• A. Chafed insulation.
• B. Excessive lubrication.
• C. Loose or corroded connectors.
• D. Overheating fans.

Answer: (C)

In aircraft electrical systems, the reliability of every circuit depends on clean, secure connections. A common fault is a connector that is loose or corroded because it directly disrupts the path electricity takes. When a connection is loose, contact resistance increases, which can cause voltage drops, heat buildup, arcing, and intermittent or complete loss of power to critical systems. Corrosion on contact surfaces does the same in a more insidious way: it raises resistance and can create unreliable contacts that fail unexpectedly, especially under vibration and thermal cycling.

Chafed insulation is a valid wiring fault too—bare conductors can short to structure or rub through and cause faults. However, from a maintenance and inspection perspective, loose or corroded connectors are encountered most frequently and tend to produce a range of symptoms across many circuits, making them the most common and impactful wiring fault.

Excessive lubrication isn’t a wiring fault; it’s a mechanical condition that can contaminate connectors or attract dirt but doesn’t directly degrade the electrical path. Overheating fans relate to cooling or motor issues rather than a wiring contact problem, though improper wiring can contribute to overheating in some cases.