What does the grade of a file indicate?

The grade of a file accurately refers to the distance between parallel rows of teeth, which directly affects the file's coarseness or fineness. The grade determines how much material the file can remove during use, with a finer grade having more closely spaced teeth, thus resulting in a smoother finish. Conversely, a coarser file, which has fewer teeth per inch, will remove material more aggressively but leave a rougher surface.

While other factors like the number of teeth per inch or the type of material can influence a file's performance, these do not define "grade" in the same context. The length of the file also does not affect its grade but can influence its application based on the workspace requirements. Understanding this definition is essential for selecting the appropriate file grade for specific tasks in aviation maintenance, ensuring efficiency and the quality of work performed.