14 C.F.R. § 11.11
A final rule with request for comment is a rule that the FAA issues in final (with an effective date) that invites public comment on the rule. We usually do this when we have not first issued an ANPRM or NPRM, because we have found that doing so would be impracticable, unnecessary, or contrary to the public interest. We give our reasons for our determination in the preamble. The comment period often ends after the effective date of the rule. A final rule not preceded by an ANPRM or NPRM is commonly called an "immediately adopted final rule." We invite comments on these rules only if we think that we will receive useful information. For example, we would not invite comments when we are just making an editorial clarification or correction.
14 C.F.R. §11.11