14 C.F.R. § 302.6 – Responsive documents.

(a) Answers. Answers to applications, complaints, petitions, motions or other documents or orders instituting proceedings may be filed by any person. In hearing cases, answers may be filed by any party to such proceedings or any person who has a petition for intervention pending. Except as otherwise provided, answers are not required.
(b) Further responsive documents. Except as otherwise provided, a reply to an answer, reply to a reply, or any further responsive document is not authorized.
(c) Motions for leave to file otherwise unauthorized documents.
1. (1) The Department will accept otherwise unauthorized documents for filing only if leave has been obtained from the DOT decisionmaker or, if applicable, the administrative law judge, on written motion and for good cause shown.
2. (2) Such motions shall contain a concise statement of the matters relied upon as good cause and shall be attached to the pleading or other document for which leave to file is sought, or the written motion may be incorporated into the otherwise unauthorized document for which admission is sought. In such event, the document filed shall be titled to describe both the motion and the underlying documents.
3. (3) Where unauthorized responsive documents are not permitted, all new matter contained in an answer filed pursuant to paragraph (a) of this section shall be deemed controverted.
(d) Time for filing. Except as otherwise provided, an answer, motion, or other further responsive document shall be filed within seven (7) days after service of any document, order, or ruling to which the proposed filing is responsive and must be served on all parties to the proceeding.