Section 1036.580 - Infrequently regenerating aftertreatment devicesFor engines using aftertreatment technology with infrequent regeneration events that may occur during testing, take one of the following approaches to account for the emission impact of regeneration on criteria pollutant and greenhouse gas emissions:
(a) You may use the calculation methodology described in 40 CFR 1065.680 to adjust measured emission results. Do this by developing an upward adjustment factor and a downward adjustment factor for each pollutant based on measured emission data and observed regeneration frequency as follows:(1) Adjustment factors should generally apply to an entire engine family, but you may develop separate adjustment factors for different configurations within an engine family. Use the adjustment factors from this section for all testing for the engine family.(2) You may use carryover data to establish adjustment factors for an engine family as described in § 1036.235(d) , consistent with good engineering judgment.(3) Identify the value of F[cycle] in each application for the certification for which it applies.(4) Calculate separate adjustment factors for each required duty cycle.(b) You may ask us to approve an alternate methodology to account for regeneration events. We will generally limit approval to cases where your engines use aftertreatment technology with extremely infrequent regeneration and you are unable to apply the provisions of this section.(c) You may choose to make no adjustments to measured emission results if you determine that regeneration does not significantly affect emission levels for an engine family (or configuration) or if it is not practical to identify when regeneration occurs. You may omit adjustment factors under this paragraph (c) for N2O, CH4, or other individual pollutants under this paragraph (c) as appropriate. If you choose not to make adjustments under paragraph (a) or (b) of this section, your engines must meet emission standards for all testing, without regard to regeneration.(d) If your engine family includes engines with one or more emergency AECDs approved under § 1036.115(h)(4) , do not consider additional regenerations resulting from those AECDs when developing adjustments to measured values under paragraph (a) or (b) of this section. 88 FR 4487 , Jan. 24, 2023, as amended at 89 FR 29763 , Apr. 22, 2024 88 FR 4487 , 3/27/2023; As amended at 89 FR 29763 , 6/21/2024