71 Pa.C.S. § 5951

The required interest charges payable, the maintenance of reserves in the fund, and the payment of all annuities and other benefits granted by the board from the system under the provisions of this part relating to the establishment and administration of the system are hereby made obligations of the Commonwealth. All income, interest, and dividends derived from deposits and investments of the system authorized by this part shall be used for the payment of the said obligations of the Commonwealth and shall not be used for any obligation of the plan or trust.