Unapproved aircraft parts are aircraft parts not approved by civil aviation authorities for installation on type certified aircraft. The Federal Aviation Administration (FAA) defines a "standard part" as a part produced in accordance with government regulations, and it defines an "approved part" as a "standard part" that is in accordance with specific a set of criteria and specifications. The FAA standards for approved parts are in FAR 21.305. In the United States parts may be approved through a Parts Manufacturer Approval (PMA), with type certification procedures through approval from the agency's approval, through Technical Standard Orders (TSOs), and from conforming to recognized specifications from the aviation industry.