The board shall appoint a secretary, who shall not be a member of the board, to hold office at the pleasure of the board and shall fix his duties and compensation. The secretary shall not be engaged in any other business or employment during his tenure of office as secretary of the board. Before entering upon the duties of the office of secretary, he shall take and subscribe the constitutional oath of office. Officers and employees of the authority, and those members of the board as the board may determine, shall execute corporate surety bonds conditioned upon the faithful performance of their respective duties. A blanket form of surety bond may be used for this purpose if the board deems this procedure to be practical and prudent. The obligation of the sureties shall not extend to any loss sustained by the insolvency, failure or closing of any national or state bank, bank and trust company or trust company wherein funds of the authority have been deposited if the bank, bank and trust company or trust company has been approved by the board as a depository for these funds. The oaths of office and the surety bond or bonds shall be filed in the principal office of the authority.