(a) Unless sooner terminated under paragraph (d) of this section, a designation as an Aviation Medical Examiner is effective for 1 year after the date it is issued, and may be renewed for additional periods of 1 year in the Federal Air Surgeon's discretion. A renewal is effected by a letter and issuance of a new identification card specifying the renewal period.

(b) Unless sooner terminated under paragraph (d) of this section, a designation as a Flight Standards and Aircraft Certification Service Designated Representative is effective for one year after the date it is issued and may be renewed for additional periods of one year in the Administrator's discretion.

(c) Unless sooner terminated under paragraph (d) of this section, a designation as a Designated Airworthiness Representative is effective until the expiration date shown on the Certificate of Authority.

(d) A designation made under this subpart terminates --

(1) Upon the written request of the representative;

(2) Upon the written request of the employer in any case in which the recommendation of the employer is required for the designation;

(3) Upon the representative being separated from the employment of the employer who recommended him for certification;

(4) Upon a finding by the Administrator that the representative has not properly performed his duties under the designation;

(5) Upon the assistance of the representative being no longer needed by the Administrator; or

(6) For any reason the Administration considers appropriate. (Secs. 313(a), 314, 601, 603, 605, and 1102, Federal Aviation Act of 1958, as amended (49 U.S.C. 1354(a), 1355, 1421, 1423, 1425, and 1502); sec. 6(c) Department of Transportation Act (49 U.S.C. 1655(c)))