FAA Powerplant Written Practice Test

What materials should be used to tie aircraft wire groups or bundles when supports are more than 12 inches apart?

1. Waxed cotton cord, nylon cord, or fiberglass cord

2. Steel wire, rubber bands, or electrical tape

3. Twist ties, plastic zip ties, or duct tape

4. Silicone string, metal wire, or cotton thread

The correct answer is: Waxed cotton cord, nylon cord, or fiberglass cord

Using waxed cotton cord, nylon cord, or fiberglass cord is the correct choice for tying aircraft wire groups or bundles with supports more than 12 inches apart due to several important considerations in aircraft maintenance and safety. These materials are preferred because they offer good durability, resistance to environmental factors, and flexibility during thermal expansion and contraction. Waxed cotton cords provide some degree of cushioning and are less likely to abrade against the wire insulation. Nylon cords are strong and resistant to moisture and chemicals, which makes them suitable for the challenging conditions that aircraft wiring may face. Fiberglass cord is recognized for its non-conductivity and lightweight properties, adding to its suitability in an aircraft environment where electrical safety is paramount. The other options provide materials that may not meet the necessary standards for safety, durability, and thermal performance required in aviation applications. For example, steel wire might introduce a risk of short-circuiting, rubber bands can degrade over time and lose elasticity, and electrical tape may not provide the structural integrity needed for longer spans. Therefore, the selected choice effectively addresses the requirements for secure and reliable tie-off of wire bundles in aircraft systems.