8 CFR § 205.1 Automatic revocation.
(a) Reasons for automatic revocation. The approval of a petition or self-petition made under section 204 of the Act and in accordance with part 204 of this chapter is revoked as of the date of approval:
(1) If the Secretary of State shall terminate the registration of the beneficiary pursuant to the provisions of section 203(e) of the Act before October 1, 1991, or section 203(g) of the Act on or after October 1, 1994;
(2) If the filing fee and associated service charge are not paid within 14 days of the notification to the remitter that his or her check or other financial instrument used to pay the filing fee has been returned as not payable; or
(3) If any of the following circumstances occur before the beneficiary's or self-petitioner's journey to the United States commences or, if the beneficiary or self-petitioner is an applicant for adjustment of status to that of a permanent resident, before the decision on his or her adjustment application becomes final:
(i) Immediate relative and family-sponsored petitions, other than Amerasian petitions. (A) Upon written notice of withdrawal filed by the petitioner or self-petitioner with any officer of the Service who is authorized to grant or deny petitions.
(B) Upon the death of the beneficiary or the self-petitioner.
(C) Upon the death of the petitioner, unless:
( 1 ) The petition is deemed under 8 CFR 204.2(i)(1)(iv) to have been approved as a Form I–360, Petition for Amerasian, Widow(er) or Special Immigrant under 8 CFR 204.2(b); or
( 2 ) U.S. Citizenship and Immigration Services (USCIS) determines, as a matter of discretion exercised for humanitarian reasons in light of the facts of a particular case, that it is inappropriate to revoke the approval of the petition. USCIS may make this determination only if the principal beneficiary of the visa petition asks for reinstatement of the approval of the petition and establishes that a person related to the principal beneficiary in one of the ways described in section 213A(f)(5)(B) of the Act is willing and able to file an affidavit of support under 8 CFR part 213a as a substitute sponsor.
***I don't see a deadline***