(a) Under a Parts Manufacturer Approval issued under §21.303;
(b) Under a Technical Standard Order issued by the Administrator. Advisory Circular 20–110 contains a list of Technical Standard Orders that may be used to obtain approval. Copies of the Advisory Circular may be obtained from the U.S. Department of Transportation, Publication Section (M–443.1), Washington, D.C. 20590;
(c) In conjunction with type certification procedures for a product; or
(d) In any other manner approved by the Administrator.
[Amdt. 21–38, 37 FR 10659, May 26, 1972, as amended by Amdt. 21–50, 45 FR 38346, June 9, 1980]