9801.00.30.00—Any aircraft engine or propeller, or any part or accessory of either, previously imported, with respect to which the duty was paid upon such previous importation, if (1) reimported without having been advanced in value or improved in condition by any process of manufacture or other means while abroad, after having been exported under loan, lease or rent to an aircraft owner or operator as a temporary replacement for an aircraft engine being overhauled, repaired, rebuilt or reconditioned in the United States, and (2) reimported by or for the account of the person who exported it from the United States