(a) Requirements for Tier 1 engines rated at or above 37 kW. A manufacturer may use averaging to offset an emission exceedance of a nonroad engine family caused by a NOX FEL above the applicable emission standard. NOX credits used in averaging may be obtained from credits generated by another engine family in the same model year, credits banked in a previous model year, or credits obtained through trading.

(b) Requirements for Tier 2 and later engines rated at or above 37 kW and Tier 1 and later engines rated under 37 kW. A manufacturer may use averaging to offset an emission exceedance of a nonroad engine family caused by an NMHC + ;NOX FEL or a PM FEL above the applicable emission standard. Credits used in averaging may be obtained from credits generated by another engine family in the same model year, credits banked in previous model years that have not expired, or credits obtained through trading. The use of credits shall be within the restrictions described in paragraph (c) of this section, §89.206(b)(4) and §89.203(b)(5)(ii).

(c) Averaging sets for emission credits. The averaging and trading of NOX emission credits, NMHC + NOX emission credits, and PM emissions credits will only be allowed between engine families in the same averaging set. The averaging sets for the averaging and trading of NOX emission credits, NMHC + NOX emission credits, and PM emission credits for nonroad engines are defined as follows:

(1) Eligible engines rated at or above 19 kW, other than marine diesel engines, constitute an averaging set.

(2) Eligible engines rated under 19 kW, other than marine diesel engines, constitute an averaging set.

(3) Marine diesel engines rated at or above 19 kW constitute an averaging set. Emission credits generated from marine diesel engines rated at or above 19 kW may be used to address credit shortfalls for eligible engines rated at or above 19 kW other than marine diesel engines.

(4) Marine diesel engines rated under 19 kW constitute an averaging set. Emission credits generated from marine diesel engines rated under 19 kW may be used to address credit shortfalls for eligible engines rated under 19 kW other than marine diesel engines.

[63 FR 57007, Oct. 23, 1998]