(c) (1) Paragraph (c) of this section applies to heavy-duty engines.
(2) Two types of service accumulation are applicable to heavy-duty engines, as described in paragraphs (c)(2)(i) and (ii) of this section. For Otto-cycle heavy-duty engines exhaust emissions, the service accumulation method used by a manufacturer must be designed to effectively predict the deterioration of emissions in actual use over the full useful life of the of the candidate in-use vehicles and must cover the breadth of the manufacturer's product line that will be covered by the durability procedure. Manufacturers not selecting Options 1 or 2 described in § 86.005-10(f) may certify Otto-cycle engines using the provisions contained in § 86.094-26(c)(2) rather than those contained in this paragraph (c)(2) for 2004 model year engine families certified using carry-over durability data, except for those engines used for early credit banking as allowed in § 86.000-15(k).
(i) Service accumulation on engines, subsystems, or components selected by the manufacturer under § 86.094-24(c)(3)(i). The manufacturer determines the form and extent of this service accumulation, consistent with good engineering practice, and describes it in the application for certification.
(ii) Dynamometer service accumulation on emission data engines selected under § 86.094-24(b)(2) or (3). The manufacturer determines the engine operating schedule to be used for dynamometer service accumulation, consistent with good engineering practice. A single engine operating schedule shall be used for all engines in an engine family-control system combination. Operating schedules may be different for different combinations.
(3) Exhaust emission deterioration factors will be determined on the basis of the service accumulation described in § 86.000-26(b)(2)(i) and related testing, according to the manufacturer's procedures.
(4) The manufacturer shall determine, for each engine family, the number of hours at which the engine system combination is stabilized for emission-data testing. The manufacturer shall maintain, and provide to the Administrator if requested, a record of the rationale used in making this determination. The manufacturer may elect to accumulate 125 hours on each test engine within an engine family without making a determination. Any engine used to represent emission-data engine selections under § 86.094-24(b)(2) shall be equipped with an engine system combination that has accumulated at least the number of hours determined under this paragraph. Complete exhaust emission tests shall be conducted for each emission-data engine selection under § 86.094-24(b)(2). Evaporative emission controls must be connected, as described in 40 CFR part 1065, subpart F. The Administrator may determine under § 86.094-24(f) that no testing is required.
(d) (1) -(d)(2)(i) [Reserved]. For guidance see § 86.094-26.