49 CFR §601.33

1. (a)In general. Each petition received under § 601.32 is referred to the head of the office responsible for the subject matter of that petition. 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 the petition contains adequate justification, he/she initiates rulemaking action under subpart C of this part or grants the exemption, as applicable.
3. (c)Denials. If the Administrator determines the petition does not justify rulemaking or granting the exemption, he/she denies the petition.
4. (d)Notification. Whenever the Administrator determines that a petition should be granted or denied, and after consultation with the Office of Regulation and Legislation in the case of denial, the office concerned and the Office of Chief Counsel prepare a notice of that grant or denial for issuance to the petitioner, and the Administrator issues it to the petitioner.