An applicant for a written, oral, or practical test for a certificate
and rating, or for an additional rating under this part, may apply for
(a) After 30 days after the date the applicant failed the test; or
(b) Before the 30 days have expired if the applicant presents a signed
statement from an airman holding the certificate and rating sought by the
applicant, certifying that the airman has given the applicant additional
instruction in each of the subjects failed and that the airman considers
the applicant ready for retesting.