(a) Number of locomotives to be tested. The manufacturer or remanufacturer shall test in-use locomotives, from an engine family selected by EPA, which have accumulated between one-half and three-quarters of the engine family's useful life. The number of locomotives to be tested by a manufacturer or remanufacturer will be determined by the following method:

(1) A minimum of 2 locomotives per engine family per year for each engine family that reaches the minimum age specified above provided that no locomotive tested fails to meet any applicable standard. For each failing locomotive, two more locomotives shall be tested until the total number of locomotives tested equals 10, except as provided in paragraph (a)(2) of this section.

(2) If an engine family has not changed from one year to the next and has certified using carry over emission data and has been previously tested under paragraph (a)(1) of this section (and EPA has not ordered or begun to negotiate remedial action of that family), then only one locomotive per engine family per year must be tested. If such locomotive fails to meet applicable standards for any pollutant, testing for that engine family must be conducted as outlined under paragraph (a)(1) of this section.

(b) At the discretion of the Administrator, a locomotive or locomotive engine manufacturer or remanufacturer may test more locomotives than the minima described above or may concede failure before locomotive number 10.

(c) The Administrator will consider failure rates, average emission levels and the existence of any defects among other factors in determining whether to pursue remedial action. The Administrator may order a recall pursuant to subpart H of this part before testing reaches the tenth locomotive.

(d) Collection of in-use locomotives. The locomotive manufacturer or remanufacturer shall procure in-use locomotives which have been operated for between one-half and three-quarters of the locomotive's useful life for testing under this subpart. The manufacturer or remanufacturer shall complete testing required by this section for any engine family before useful life of the locomotives in the engine family passes.