(a) A charge on the revenue derived from the improvements and facilities of the authority may not be made if the principal or interest of any obligation issued under this chapter is unpaid.
(b) If the revenue derived from the improvements and facilities of the authority exceed the amount required for the payment of items under Section 8501.204(c), the board may pay the cost of improvements and replacements not covered by Section 8501.204(c)(1) and may establish a reasonable depreciation and emergency fund.