119.61—Duration and surrender of certificate and operations specifications.
(b)
Operations specifications issued under this part, part 121, or part 135 of this chapter are effective unless—
(3)
The certificate holder does not conduct a kind of operation for more than the time specified in § 119.63 and fails to follow the procedures of § 119.63 upon resuming that kind of operation; or
(c)
Within 30 days after a certificate holder terminates operations under part 135 of this chapter, the operating certificate and operations specifications must be surrendered by the certificate holder to the certificate-holding district office.