§ 1068.50 Adjustable parameters.

(a) The standard-setting part requires as a condition of certification that engines with adjustable parameters meet all the requirements of the standard-setting part for any setting in the practically adjustable range. This section defines these terms and describes general provisions that apply broadly across sectors. This section refers to engines, because most adjustable parameters are integral to the engine even in the case of equipment-based standards; this section also applies for equipment-based adjustable parameters. The provisions of this section apply starting with model year 2027 and are optional for earlier model years.

(b) You must use good engineering judgment for all decisions related to adjustable parameters. We recommend that you ask for preliminary approval for decisions related to new technologies, substantially changed engine designs, or new methods for limiting adjustability. The standard-setting part describes the information you must include in the application for certification related to adjustable parameters. Decisions related to adjustable parameters include the following:

(1) Determining which engine operating parameters qualify as adjustable parameters.

(2) Establishing the adequacy of the limits, stops, seals, programming limits, inducements, or other means used to limit adjustment, limit reprogramming, or ensure replenishment.

(3) Defining the practically adjustable range for each such parameter.

(c) For purposes of this section, “operating parameter” means any feature that can, by the nature of its design, be adjusted to affect engine performance. For example, while bolts used to assemble the engine are practically adjustable (can be loosened or tightened), they are not adjustable parameters because they are not operating parameters. Consider all programmable parameters not involving user-selectable controls to be a single, collective operating parameter.

(d) Operating parameters are considered adjustable parameters if they are practically adjustable by a user or other person by physical adjustment, programmable adjustment, or regular replenishment of a fluid or other consumable material. However, an operating parameter is not an adjustable parameter if—

(1) We determine it is permanently sealed or it is not practically adjustable using available tools, as described in paragraph (e) of this section; or

(2) We determine that engine operation over the full range of adjustment does not affect emissions without also degrading engine performance to the extent that operators will be aware of the problem.