Which of the following is NOT considered a common tool used in aircraft maintenance?

In the context of aircraft maintenance, a circular saw is not considered a common tool. Aircraft maintenance primarily involves working with various components and systems that require precision and care to ensure safety and functionality. Common tools in aircraft maintenance include items like a torque wrench, which is essential for applying a specified torque to fasteners; wire strippers, crucial for preparing electrical wiring; and pliers, which are versatile tools used to grip, twist, and cut wires or other materials.

On the other hand, a circular saw is primarily designed for cutting through heavy materials like wood or metal in a construction setting and is generally not used in aircraft maintenance due to the need for precision and the potential for causing structural damage. Therefore, the inclusion of a circular saw in the list of common tools used for maintaining aircraft is inappropriate, making it the correct answer to the question.