A few decades ago the term maintenance was associated only with responding to faults or machine failures. In the 60s and 70s production centres contained very simple machinery with sufficient employees to repair any breakdowns. There was no thought of preventative or statusoriented maintenance and there was very little automation of systems. As systems grew more complex and stoppage costs increased, companies gradually began to plan cyclical maintenance activities to increase system availability, reduce costs and to increase the service life of their machinery.