Section 121.1101 - Purpose and definition(a) This subpart requires persons holding an air carrier or operating certificate under part 119 of this chapter to support the continued airworthiness of each airplane. These requirements may include, but are not limited to, revising the maintenance program, incorporating design changes, and incorporating revisions to Instructions for Continued Airworthiness.Amdt. 121-336, 72 FR 63411 , Nov. 8, 2007, as amended by Docket FAA-2018-0119, Amdt. 121-380, 83 FR 9173 , Mar. 5, 2018