(a) At the start of each model year, the manufacturer or remanufacturer will begin to randomly select locomotives or locomotive engines from each engine family for production line testing at a rate of one percent. Each locomotive or locomotive engine will be selected from the end of the production line. Testing shall be performed throughout the entire model year to the extent possible.

(1) The required sample size for an engine family is the lesser of five tests per model year or one percent of projected annual production, with a minimum sample size for an engine family of one test per model year provided that no engine tested fails to meet applicable emission standards.

(2) Manufacturers and remanufacturers may elect to test additional locomotives or locomotive engines. All additional locomotives or locomotive engines must be tested in accordance with the applicable test procedures of this part.

(b) The manufacturer or remanufacturer must assemble the test locomotives or locomotive engines using the same mass production process that will be used for locomotives or locomotive engines to be introduced into commerce.

(c) No quality control, testing, or assembly procedures will be used on any test locomotive or locomotive engine or any portion thereof, including parts and subassemblies, that have not been or will not be used during the production and assembly of all other locomotives or locomotive engines of that family, except with the approval of the Administrator.