14 CFR §13.214

1. (a)Filing and service. A party must file the amendment with the FAA Hearing Docket and must serve a copy of the amendment on the administrative law judge, if assigned, and on all parties to the proceeding.
2. (b)Time.
   1. (1)Not later than 15 days before the scheduled date of a hearing, a party may amend a complaint or an answer without the consent of the administrative law judge.
   2. (2)Less than 15 days before the scheduled date of a hearing, the administrative law judge may allow amendment of a complaint or an answer only for good cause shown in a motion to amend.
3. (c)Responses. The administrative law judge must allow a reasonable time, but not more than 20 days from the date of filing, for other parties to respond if an amendment to a complaint, answer, or other pleading has been filed with the FAA Hearing Docket and served on the administrative law judge and other parties.