49 CFR §386.64

1. (a)Within 20 days following service of the Final Order, any party may petition the Agency Decisionmaker for reconsideration of the order. If a civil penalty was imposed, the filing of a petition for reconsideration stays the entire action, unless the Agency Decisionmaker orders otherwise.
2. (b)In the event a Notice of Default and Final Order is issued by the Field Administrator as a result of the respondent's failure to reply in accordance with § 386.14(a), the only issue that will be considered upon reconsideration is whether a default has occurred under § 386.14(c). The Final Order may be vacated where a respondent can demonstrate excusable neglect, a meritorious defense, or due diligence in seeking relief.
3. (c)Either party may serve an answer to a petition for reconsideration within 30 days of the service date of the petition.
4. (d)Following the close of the 30-day period, the Agency Decisionmaker will rule on the petition.
5. (e)The ruling on the petition will be the Final Agency Order. A petition for reconsideration of the Agency Decisionmaker's ruling will not be permitted.