Source: http://www.faa-aircraft-certification.com/far-47-15.html
Timestamp: 2019-04-18 20:46:31+00:00

Document:
(a) Number required. An applicant for aircraft registration must place a U.S. registration number (registration mark) on the Aircraft Registration Application, AC Form 8050–1, and on any evidence submitted with the application. There is no charge for the assignment of numbers provided in this paragraph. This paragraph does not apply to an aircraft manufacturer who applies for a group of U.S. registration numbers under paragraph (c) of this section; a person who applies for a special registration number under paragraphs (d) through (f) of this section; or a holder of a Dealer's Aircraft Registration Certificate, AC Form 8050–6, who applies for a temporary registration number under 47.16.
(1) Aircraft not previously registered anywhere. The applicant must obtain the U.S. registration number from the Registry by request in writing describing the aircraft by make, type, model, and serial number (or, if it is amateur-built, as provided in §47.33(b)) and stating that the aircraft has not previously been registered anywhere. If the aircraft was brought into the United States from a foreign country, the applicant must submit evidence that the aircraft has never been registered in a foreign country.
(2) Aircraft last previously registered in the United States. Unless the applicant applies for a different number under paragraphs (d) through (f) of this section, the applicant must place the U.S. registration number that is already assigned to the aircraft on the Aircraft Registration Application, and the supporting evidence. If there is no number assigned, the applicant must obtain a U.S. registration number from the Registry by making a written request that describes the aircraft by make, model, and serial number.
(ii) If foreign registration has not ended, the applicant's affidavit stating that the number will not be placed on the aircraft until foreign registration has ended.
(4) Duration of a U.S. registration number assignment. Authority to use the registration number obtained under paragraph (a)(1), (2), or (3) of this section expires 90 days after the date it is issued unless the applicant submits an Aircraft Registration Application and complies with §47.33 or §47.37, as applicable, within that period of time. However, the applicant may obtain an extension of this 90-day period from the Registry if the applicant shows that the delay in complying with that section is due to circumstances beyond the applicant's control.
(b) A U.S. registration number may not exceed five symbols in addition to the prefix letter “N”. These symbols may be all numbers (N10000), one to four numbers and one suffix letter (N 1000A), or one to three numbers and two suffix letters (N 100AB). The letters “I” and “O” may not be used. The first zero in a number must always be preceded by at least one of the numbers 1 through 9.
(c) An aircraft manufacturer may apply to the Registry for enough U.S. registration numbers to supply estimated production for the next 18 months. There is no charge for this allocation of numbers.
(d) Any available, unassigned U.S. registration number may be assigned as a special registration number. An applicant who wants a special registration number or wants to change the registration number of his aircraft may apply for it to the Registry. The fee required by §47.17 must accompany the application.
(f) The Registry authorizes a special registration number change on the Assignment of Special Registration Numbers, AC Form 8050–64. The authorization expires one year from the date the Registry issues an Assignment of Special Registration Numbers unless the special registration number is permanently placed on the aircraft. Within five days after the special registration number is placed on the aircraft, the owner must complete and sign the Assignment of Special Registration Numbers, state the date the number was placed on the aircraft, and return the original form to the Registry. The duplicate of the Assignment of Special Registration Numbers and the present Certificate of Aircraft Registration, AC Form 8050–3, must be carried in the aircraft as temporary authority to operate it. This temporary authority is valid until the date the owner receives the revised Certificate of Aircraft Registration showing the new registration number, but in no case is it valid for more than 120 days from the date the number is placed on the aircraft.
(h) A special registration number may be reserved for no more than 1 year. If a person wishes to renew his reservation from year to year, he must apply to the Registry for renewal and submit the fee required by §47.17 for a special registration number.
(i) Six months after first receipt of notice of aircraft sale or evidence of ownership from the last registered owner or successive owners, and an Aircraft Registration Application has not been received.
(ii) Six months after evidence of ownership authorized under §47.67 has been submitted, and the applicant has not met the requirements of this part.
(iii) Twelve months after a new owner has submitted evidence of ownership and an Aircraft Registration Application under §47.31, and the applicant or a successive applicant has not met the requirements of this part.
(j) At the time an assignment of registration number is cancelled, the number may be reserved for one year in the name of the last owner of record if a request has been submitted with the fee required by §47.17. If the request for reservation and fee are not submitted prior to cancellation, the registration number is unavailable for assignment for a period of five years.

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