Any city may at any time and from time to time issue its revenue refunding bonds for the purpose of refunding any outstanding bonds issued under this act or issued for a purpose for which revenue bonds are issuable under this act whether issued before or after the effective date of this act, upon compliance with the provisions of this act applicable to an original issue of revenue bonds whether or not the bonds to be refunded shall have matured or are about to mature, and whether or not the principal of or interest on the refunding bonds shall exceed the principal of or interest on the bonds to be refunded, but the last stated maturity date of the refunding bonds shall be no later than ten years after the last stated maturity of the bonds to be refunded. Such revenue refunding bonds may be exchanged for outstanding bonds to be refunded or may be sold and the proceeds applied to the purchase, redemption or payment of the bonds to be refunded. If bonds, whether revenue or general obligation, of two or more issues or series are to be refunded with one issue or series of revenue refunding bonds, the limitation of this section with respect to the latest date of maturity of the refunding bonds will be met if the serial maturity dates or scheduled mandatory redemption dates of the refunding bonds may be stated, pro forma, in blocks of maturities or mandatory redemption dates applicable to the refunding of each such issue or series to be refunded which are within the limitation and if the proceeds of each such block will be sufficient together with other available funds and together with earnings thereon to the respective dates fixed for redemption or payment to effect the redemption or payment of the applicable bonds to be refunded.
For the purpose of ascertaining the sufficiency of revenues for the purpose of clause (5) of subsection (a) of section 7 of this act and of clause (iii) of subsection (a) of section 8 of this act and for the purpose of determining the outstanding net debt of the city if general obligation bonds of the city are refunded hereunder, the principal of and interest to payment or redemption date and redemption premium payable, if any, in respect of the bonds to be refunded shall no longer be deemed to be outstanding obligations of the city:
53 P.S. § 15910