View all text of Subpart A [§ 21.1 - § 21.9]
§ 21.8 - Approval of articles.
If an article is required to be approved under this chapter, it may be approved—
(a) Under a PMA;
(b) Under a TSO;
(c) In conjunction with type certification procedures for a product; or
(d) In any other manner approved by the FAA.