(1) In the discretion of the governing body of the authority, any series of bonds issued pursuant to the authorization of section 12b may be secured by a trust indenture by and between the authority and a corporate trustee, which may be any trust company or bank having the powers of a trust company within or without the state, but no trust indenture shall convey or mortgage the project or any part of the project. Either the resolution providing for the issuance of bonds or the trust indenture may contain the provisions for the security and payment of the bonds and for the protection and enforcement of the rights and remedies of the bondholders as deemed advisable by the governing body of the authority, not in violation of the constitution of this state, including specifically covenants setting forth the following:

    (a) The duties of the authority in relationship to the construction, maintenance, operation, repair, and insurance of the project.

    (b) The pledge of revenues of the project or any part of the project.

    (c) Limitations on the amount of money derived from the operation of the project that may be expended for operating, administrative, or other specified expenses of the authority.

    (d) The safeguarding and application of the fund from which the cost of the project is to be paid and of the revenues pledged to the payment of the bonds, all of which may be deposited in as received and paid out by those banks as provided in the resolution or indenture.

    (e) Provisions for the employment of consulting engineers to supervise the construction of the project, and to supervise its maintenance and operation, to which consulting engineers may be delegated all rights and duties with respect to the project deemed advisable by the governing body of the authority and the appointment of which consulting engineers shall be subject to the approval by the purchasers or holders of the bonds as provided in the resolution or indenture.

    (f) Rights and remedies of the bondholders and the trustee, if any, and the restrictions thereon as may be considered advisable.

    (g) Any other and additional provisions ordinarily found in trust agreements securing bond issues protecting and enforcing the rights and security of the holders of the bonds and designed to make the bonds more attractive and salable at the best available prices.

    (2) The resolution or trust indenture shall contain a provision requiring an annual audit of the books and records of the authority, or any fiscal agent or trustee specified in the resolution or trust indenture by a certified public accountant or accountants to be selected by the governing body of the authority and approved by the manager or managers of the account purchasing the bonds.

    (3) Any bank or trust company designated as trustee or as depositary for any funds, notwithstanding any provision of law to the contrary, is authorized to pledge as collateral security for moneys deposited in such bank or trust company direct obligations of, or obligations the principal and interest of which are unconditionally guaranteed by the government of the United States, or other marketable securities eligible as security for the deposit of trust funds under regulations of the federal reserve board and having a market value, exclusive of accrued interest, at least equal to the amount of the deposit; or in lieu of the collateral security as to all or any part of the deposit, there may be lodged with the trustee, or with the governing body of the authority in case of moneys deposited or remaining on deposit with the trustee, and remain in full force and effect as security for the moneys deposited, the indemnifying bonds of a surety company or companies qualified as surety for deposits of the government of the United States and qualified to transact business in this state, in a sum at least equal to the amount of moneys deposited with such bank or trust company, if such indemnity bond or bonds be approved by the governing body of the authority. All expenses incurred in carrying out the provisions appearing in any trust indenture or bond resolution and the cost of any surety bond furnished may be treated as part of the cost of maintaining and operating the project. The resolution or trust indenture may contain such other provisions as the governing body of the authority may deem reasonable and proper for the security of the bondholders, including, but without limitation, covenants prescribing all happenings or occurrences that constitute events of default and the terms and conditions upon which bonds may become or be declared to be due before maturity and as to the rights, liabilities, powers, and duties arising upon the breach by the authority of any of its duties and obligations.

    (4) Nothing contained in the 1958 amendments to this act shall be construed to authorize the issuance of other than revenue bonds.