(a) Testing conducted under this subpart shall be conducted on locomotives; testing under this subpart shall not be conducted using an engine that is not installed in a locomotive at the time of testing.

(b) Locomotives tested under this subpart shall be tested using the locomotive test procedures outlined in subpart B of this part, except as provided in this section.

(c) The test procedures used for in-use testing shall be consistent with the test procedures used for certification, except for cases in which certification testing was not conducted with locomotive, but with a development engine, or other engine. In such cases, the Administrator shall require deviations from the certification test procedures as appropriate, including requiring that the test be conducted on a locomotive. The Administrator may allow or require other alternate procedures, with advance approval. For all testing conducted under this subpart, emission rates shall be calculated in accordance with the provisions of subpart B of this part that apply to locomotive testing.

(d) Any adjustable locomotive or locomotive engine parameter must be set to values or positions that are within the range specified in the certificate of conformity. If so directed by the Administrator, the manufacturer or remanufacturer will set these parameters to values specified by the Administrator.

(e) The Administrator may waive portions or requirements of the applicable test procedure, if any, that are not necessary to determine in-use compliance.