14 CFR §11.31

1. (a)A direct final rule will take effect on a specified date unless FAA receives an adverse comment within the comment period—generally 60 days after the direct final rule is published in the Federal Register. An adverse comment explains why a rule would be inappropriate, or would be ineffective or unacceptable without a change. It may challenge the rule's underlying premise or approach. Under the direct final rule process, we do not consider the following types of comments to be adverse:
   1. (1)A comment recommending another rule change, in addition to the change in the direct final rule at issue. We consider the comment adverse, however, if the commenter states why the direct final rule would be ineffective without the change.
   2. (2)A frivolous or insubstantial comment.
2. (b)If FAA has not received an adverse comment, we will publish a confirmation document in the Federal Register, generally within 15 days after the comment period closes. The confirmation document tells the public the effective date of the rule.
3. (c)If we receive an adverse comment, we will advise the public by publishing a document in the Federal Register before the effective date of the direct final rule. This document may withdraw the direct final rule in whole or in part. If we withdraw a direct final rule because of an adverse comment, we may incorporate the commenter's recommendation into another direct final rule or may publish a notice of proposed rulemaking.