When any municipal airport improvement district of a city of the first class has paid out and fully retired its bonded indebtedness, and there remains a surplus of money or property in the district, the commissioners of the district, after payment of all obligations of the district, shall pay the surplus funds and transfer the property to the city, and the city shall use any such funds and property so received for the sole purpose of making improvements upon the municipal airport of the city.
Ark. Code § 14-89-1304