14 C.F.R. § 16.219
(a) Request for subpoena. A party may apply to the hearing officer, within the time specified for such applications in the prehearing conference report, for a subpoena to compel testimony at a hearing or to require the production of documents only from the following persons:
(b) Issuance and service of subpoena.
(c) Motions to quash or modify subpoena.