49 CFR §389.11

Except as provided in § 389.39, Direct final rulemaking procedures, unless the Administrator, for good cause, finds a rule is impractical, unnecessary, or contrary to the public interest, and incorporates such a finding and a brief statement for the reason for it in the rule, a notice of proposed rulemaking must be issued, and interested persons are invited to participate in the rulemaking proceedings involving rules under an Act.