Duration.

§ 21.77 Duration. (a) Unless sooner surrendered, superseded, revoked, or otherwise terminated, provisional type certificates and amendments thereto are effective for the periods specified in this section. (b) A Class I provisional type certificate is effective for 24 months after the date of issue. (c) A Class II provisional type certificate is effective for twelve months after the date of issue. (d) An amendment to a Class I or Class II provisional type certificate is effective for the duration of the amended certificate. (e) A provisional amendment to a type certificate is effective for six months after its approval or until the amendment of the type certificate is approved, whichever is first. [Doc. No. 5085, 29 FR 14566, Oct. 24, 1964, as amended by Amdt. 21-7, 30 FR 14311, Nov. 16, 1965]