In my experience the figure of ten thousand hours does not mean much and I work on a standard Bell medium twin civilian operations. Owning and maintaining a helicopter is like owning a 1910 Rolls Royce, you maintain to the approved maintenance schedule. Change the bits when due and be just as observant as when the machine was younger. That may be an over simplification and some types of helicopters or ones that did logging will have bits work loose or cracks. Find them and fix them.