(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.
Authority to use the identification number obtained under paragraph (a)(1) or (3) of this section expires 90 days after the date it is issued unless the applicant submits an Aircraft Registration Application, AC Form 8050-1, 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 FAA Aircraft Registry if he shows that his delay in complying with that section is due to circumstances beyond his control.

(b) A U.S. identification 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 FAA Aircraft Registry for enough U.S. identification numbers to supply his estimated production for the next 18 months. There is no charge for this assignment of numbers.
(d) Any unassigned U.S. identification number may be assigned as a special identification number. An applicant who wants a special identification number or wants to change the identification number of his aircraft may apply for it to the FAA Aircraft Registry. The fee required by §47.17 must accompany the application.
(e) [Reserved]
(f) The FAA Aircraft Registry assigns a special identification number on AC Form 8050-64. Within 5 days after he affixes the special identification number to his aircraft, the owner must complete and sign the receipt contained in AC Form 8050-64, state the date he affixed the number to his aircraft, and return the original form to the FAA Aircraft Registry. The owner shall carry the duplicate of AC Form 8050-64 and the present Certificate of Aircraft Registration 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 issued by the FAA Aircraft Registry.
(g) [Reserved]
(h) A special identification 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 FAA aircraft Registry for renewal and submit the fee required by §47.17 for a special identification number.
[Doc. No. 7190, 31 FR 4495, Mar. 17, 1966, as amended by Amdt. 47-1, 31 FR 13314, Oct. 14, 1966; Amdt. 47-5, 32 FR 13505, Sept. 27, 1967; Amdt. 47-7, 34 FR 2480, Feb. 21, 1969; Amdt. 47-13, 36 FR 16187, Aug. 20, 1971; Amdt. 47-15, 37 FR 21528, Oct. 12, 1972; Amdt. 47-16, 37 FR 25487, Dec. 1, 1972; Amdt. 47-17, 39 FR 1353, Jan. 8, 1974; Amdt. 47-22, 47 FR 12153, Mar. 22, 1982]