When a component of equipment experience a failure,the nature and cause of failure should be investigated and analyzed.Root cause analysis is important to determine the cause of breakdown so that steps can be taken to manage the cause and avoid them in future.In repairs and maintenance of equipment the Revalidation could be avoided but be sure to assess whether quality is affected and how much .where no significant change is made during maintenance of equipment a quality review confirms that process is consistently producing material meeting its specification ,there is no need for Revalidation .