Can I fly an aircraft with the registration expired?
ANSWER: For U.S. registered aircraft, No. Refer to the following regulation:
FAR 91.203 - Certifications Required
(a) Except as provided in §91.715 (Special flight authorizations for foreign civil aircraft), no person may operate a civil aircraft unless it has within it the following:
(2) An effective U.S. registration certificate issued to its owner or, for operation within the United States, the second duplicate copy (pink) of the Aircraft Registration Application as provided for in §47.31(b), or a registration certificate issued under the laws of a foreign country.