FAA Powerplant Written Practice Test

What tool is used to polish commutators or slip rings?

1. Coarse sandpaper

2. Very fine sandpaper

3. Grinding wheel

4. Metal file

The correct answer is: Very fine sandpaper

Polishing commutators or slip rings is a delicate task that requires a tool that can provide a smooth surface without causing damage. Very fine sandpaper is specifically designed for this purpose because it helps to remove surface imperfections and oxidation while leaving an even finish. Using very fine sandpaper reduces the risk of creating scratches or grooves that could affect the electrical conductivity or mechanical fit of the component. Coarse sandpaper, in contrast, is too abrasive and could lead to unnecessary removal of material or damage to the surface. It may create scratches that are too deep, potentially leading to operational issues. A grinding wheel can also be overly aggressive for this type of work, potentially removing too much material and compromising the function of the commutator or slip ring. Lastly, while a metal file can be used for some applications, it lacks the smoothness and ease of use that very fine sandpaper provides when it comes to achieving a polished finish. Therefore, very fine sandpaper is preferred for polishing these components effectively.