(a) Notification of Commission. In all cases where licenses are issued for projects already constructed, but which are not subject to the provisions of section 23(a) of the Act (49 Stat. 846; 16 U.S.C. 816), the licensee shall, within 6 months after the date of issuance of license, file with the Commission a letter, in quadruplicate.

(b) Contents of letter. The letter referred to in paragraph (a) of this section shall contain a statement to the effect that an inventory in detail of all property included under the license, as of the effective date of such license, has been completed. The letter shall also include a statement to the effect that actual legitimate original cost, or if not known, the estimated original cost, and accrued depreciation of the property, classified by prime accounts as prescribed in the Commission's Uniform System of Accounts, have been established.

(c) Licensee's books. The licensee's books of account for each project shall be maintained in such a fashion that each year's additions, betterments, and deletions to the project may be readily ascertained.

(d) Availability of information to the public. The information made available to the Commission in accordance with this section must be available for inspection and copying by the public when specifically requested.

(e) Compliance with the Act. Compliance with the provisions of this section satisfies the filing requirements of section 4(b) of the Federal Power Act (16 U.S.C. 797(b)).