FAA Powerplant Written Practice Test

When is aluminum a preferred conductor in an aircraft environment?

1. When flexibility is required

2. When the intensity of corona is a concern

3. When weight is a critical factor

4. When cost is a primary consideration

The correct answer is: When the intensity of corona is a concern

Aluminum is often chosen as a conductor in aircraft environments primarily due to its strength-to-weight ratio, making it particularly advantageous when weight is a critical factor. In the context of electricity, the concern about corona discharge—a phenomenon that occurs in high voltage systems—arises when the electric field around conductors becomes strong enough to ionize the surrounding air, leading to energy loss and potential overheating. Aluminum's lower density compared to copper allows for longer runs of wire at a lower overall weight, reducing the aircraft's total mass and contributing to fuel efficiency. Additionally, aluminum's oxidation resistance can mitigate some concerns related to corona discharge in practical applications, as aluminum oxide provides a protective layer. Although flexibility and cost are relevant considerations in conductor choice, neither takes precedence in the same way as the implications of weight and corona discharge. Fire resistance or costs should not overshadow the fundamental electrical properties needed for the specific operational requirements of aircraft systems. Thus, while aluminum offers certain advantages in particular situations, its selection is most pronounced when addressing weight as a critical factor in the design of aircraft electrical systems.