In Class 2 municipalities, the gross proceeds of the sale or sales of materials or supplies to any person for the use in fulfilling a contract for the painting, repair, conversion, modification, or reconditioning of aircraft of 30,000 pounds gross weight or greater shall be exempt from county sales and use tax; provided, however, that the exemption herein shall only apply to those materials and supplies which enter into and become a component part of such aircraft.
Ala. Code § 11-44C-94.1 (1975)