40 CFR 91.119 - Certification procedure
(a) Use of special test procedures by EPA. The Administrator may establish special test procedures for any engine that the Administrator determines is not susceptible to satisfactory testing under the specified test procedures set forth in subpart E of this part.
(b) Use of alternative test procedures by an engine manufacturer. (1) A manufacturer may elect to use an alternative test procedure provided that it yields results equivalent to the results from the specified test procedure in subpart E, its use is approved in advance by the Administrator, and the basis for equivalent results with the specified test procedures is fully described in the manufacturer's application.
(2) An engine manufacturer electing to use alternate test procedures is solely responsible for the results obtained. The Administrator may reject data generated under test procedures which do not correlate with data generated under the specified procedures.
(3) A manufacturer may elect to use the test procedures in 40 CFR part 1065 as an alternate test procedure without getting advance approval by the Administrator or meeting the other conditions of paragraph (b)(1) of this section. The manufacturer must identify in its application for certification that the engines were tested using the procedures in 40 CFR part 1065. For any EPA testing with engines subject to standards under this part, EPA will use the manufacturer's selected procedures for mapping engines, generating duty cycles, and applying cycle-validation criteria. For any other parameters, EPA may conduct testing using either of the specified procedures.
(4) Where we specify mandatory compliance with the procedures of 40 CFR part 1065, manufacturers may elect to use the procedures specified in 40 CFR part 86, subpart N, as an alternate test procedure without advance approval by the Administrator.