14 C.F.R. § 21.310 – Inspections and tests.

(a) Each applicant for or holder of a PMA must allow the FAA to inspect its quality system, facilities, technical data, and any manufactured articles and witness any tests, including any inspections or tests at a supplier facility, necessary to determine compliance with this subchapter.
(b) Unless otherwise authorized by the FAA, the applicant or holder—
1. (1) May not present any article to the FAA for an inspection or test unless compliance with § 21.303(b)(2) through (4) has been shown for that article; and
2. (2) May not make any change to an article between the time that compliance with § 21.303(b)(2) through (4) is shown for that article and the time that the article is presented to the FAA for the inspection or test.