Maintenance includes those tasks required to maintain or restore the airworthiness of an aircraft and its systems, components, and structures. Regulators require that an operator establish a maintenance and inspection program to accomplish those tasks, carried out by certified personnel. Engineering departments have primary responsibility for deciding how to establish and implement such programs. There is a growing trend for airlines, particularly startups or low-cost carriers (LCC), to forego the expense of setting up full-service maintenance departments, opting instead to outsource some or all of these services.