49 CFR §389.33

1. (a)Unless the Administrator otherwise specifies, no public hearing, argument, or other proceeding is held directly on a petition before its disposition under this section.
2. (b)Grants. If the Administrator determines that the petition contains adequate justification, he/she initiates rule making action under this Subpart B.
3. (c)Denials. If the Administrator determines that the petition does not justify rule making, he/she denies the petition.
4. (d)Notification. Whenever the Administrator determines that a petition should be granted or denied, the Office of the Chief Counsel prepares a notice of that grant or denial for issuance to the petitioner, and the Administrator issues it to the petitioner.