In engineering, maintainability is the ease with which a product can be maintained in order to: * correct defects or their cause, * Repair or replace faulty or worn-out components without having to replace still working parts, * prevent unexpected working conditions, * maximize a product's useful life, * maximize efficiency, reliability, and safety, * meet new requirements, * make future maintenance easier, or * cope with a changing environment. In telecommunication and several other engineering fields, the term maintainability has the following meanings: