19 C.F.R. § 10.15
Fabricated components which are not products of the United States are excluded from the exemption. In addition, the exemption is not applicable to any component exported from the Customs territory of the United States:
Example. Partially completed components of an electric motor are imported in several separate shipments and are entered under a temporary importation bond to be manufactured into finished motors under the provisions of subheading 9813.00.05, HTSUS (19 U.S.C. 1202 ) . The components are completed and assembled into finished electric motors. The finished motors are exported and are assembled abroad into electric fans which are subsequently imported into the United States. Irrespective of the fact that the assembly of the motors might involve such a substantial change that the motor could be considered a product of the United States, no exemption may be given for the value of the electric motors, since they were exported after manufacture or production in the United States under the provision of subheading 9813.00.05, HTSUS (19 U.S.C. 1202 ).
19 C.F.R. §10.15