The council may issue certificates of indebtedness or capital notes to purchase equipment to be owned and used by the council and having an expected useful life of at least as long as the terms of the certificates or notes. The certificates or notes shall be payable in not more than five years and shall be issued on such terms and in such manner as the council may determine, and for this purpose the council may secure payment of the certificates or notes by resolution or by trust indenture entered into by the council with a corporate trustee within or outside the state, and by a mortgage in the equipment financed. The total principal amount of the notes or certificates issued in a fiscal year should not exceed one-half of one percent of the tax capacity of the metropolitan area for that year. The full faith and credit of the council shall be pledged to the payment of the certificates or notes, and a tax levy shall be made for the payment of the principal and interest on the certificates or notes, in accordance with section 475.61, as in the case of bonds issued by a municipality. The tax levy authorized by this section must be deducted from the amount of taxes the council is otherwise authorized to levy under section 473.249.