14 CFR 49.13 – Signatures and acknowledgements
(a) Each signature on a conveyance must be signed in a manner acceptable to the Administrator.
(b) Paragraphs (b) through (f) of § 47.13 of this chapter apply to a conveyance made by, or on behalf of, one or more persons doing business under a trade name, or by an agent, corporation, partnership, coowner, or unincorporated association.
(c) No conveyance or other instrument need be acknowledged, as provided in 49 U.S.C. § 44107(c), in order to be recorded under this part. The law of the place of delivery of the conveyance determines when a conveyance or other instrument must be acknowledged in order to be valid for the purposes of that place.
(d) A power of attorney or other evidence of a person’s authority to sign for another, submitted under this part, is valid for the purposes of this section, unless sooner revoked, until—
(1) Its expiration date stated therein; or
(2) If an expiration date is not stated thereon, for not more than 3 years after the date—
(i) It is signed; or
(ii) The grantor (a corporate officer or other person in a managerial position therein, where the grantor is a corporation) certifies in writing that the authority to sign shown by the power of attorney or other evidence is still in effect.