40 CFR § 1051.740 - Are there special averaging provisions for snowmobiles?
For snowmobiles, you may only use credits for the same phase or set of standards against which they were generated, except as allowed by this section.
(a) Restrictions.
(1) You may not use any Phase 1 or Phase 2 credits for Phase 3 compliance.
(2) You may not use Phase 1 HC credits for Phase 2 HC compliance. However, because the Phase 1 and Phase 2 CO standards are the same, you may use Phase 1 CO credits for compliance with the Phase 2 CO standards.
(b) Special credits for next phase of standards. You may choose to generate credits early for banking for purposes of compliance with later phases of standards as follows:
(1) If your corporate average emission level at the end of the model year exceeds the applicable (current) phase of standards (without the use of traded or previously banked credits), you may choose to redesignate some of your snowmobile production to a calculation to generate credits for a future phase of standards. To generate credits the snowmobiles designated must have an FEL below the emission level of that set of standards. This can be done on a pollutant specific basis.
(2) Do not include the snowmobiles that you redesignate in the final compliance calculation of your average emission level for the otherwise applicable (current) phase of standards. Your average emission level for the remaining (non-redesignated) snowmobiles must comply with the otherwise applicable (current) phase of standards.
(3) Include the snowmobiles that you redesignate in a separate calculation of your average emission level for redesignated engines. Calculate credits using this average emission level relative to the specific pollutant in the future phase of standards. These credits may be used for compliance with the future standards.
(4) For generating early Phase 3 credits, you may generate credits for HC or CO separately as described:
(i) To determine if you qualify to generate credits in accordance with paragraphs (b)(1) through (3) of this section, you must meet the credit trigger level. For HC this value is 75 g/kW-hr. For CO this value is 200 g/kW-hr.
(ii) HC and CO credits for Phase 3 are calculated relative to 75 g/kW-hr and 200 g/kW-hr values, respectively.
(5) Credits can also be calculated for Phase 3 using both sets of standards. Without regard to the trigger level values, if your net emission reduction for the redesignated averaging set exceeds the requirements of Phase 3 in § 1051.103 (using both HC and CO in the Phase 3 equation in § 1051.103), then your credits are the difference between the Phase 3 reduction requirement of that section and your calculated value.