(a) Notification of Commission. In every case arising under section 23(a) of the Federal Power Act that requires the determination of the fair value of a project already constructed, the licensee shall, within six months after the date of issuance of a license, file with the Commission a letter, in quadruplicate.

(b) Contents of letter. The letter referred to in paragraph (a) shall contain a statement to the effect that an inventory and appraisal in detail, as of the effective date of the license, of all property subject thereto and to be so valued has been completed. The letter shall also include a statement to the effect that the 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 projects 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.