The definitions of this section apply to this subpart.

Agency means the Environmental Protection Agency.

Certified equipment or Retrofit/Rebuild Equipment means equipment certified in accordance with the certification regulations contained in this subpart.

Emission related parts means those parts installed for the specific purpose of controlling emissions or those components, systems, or elements of design which must function properly to assure continued emission compliance.

Engine configuration means the set of components, tolerances, specifications, design parameters, and calibrations related to the emissions performance of the engine and specific to a subset of an engine family having a unique combination of displacement, fuel injection calibration, auxiliary emission control devices and emission control system components.

Engine rebuild means an activity, occurring over one or more maintenance events, involving:

(1) Disassembly of the engine including the removal of the cylinder head(s); and

(2) The replacement or reconditioning of more than one major cylinder component in more than half of the cylinders.

Engine replacement means the removal of an engine from the coach followed by the installation of another engine.

In-use compliance period for purposes of in-use testing means a period of 150,000 miles.

Maintenance event means a single maintenance activity for which the engine is removed from service. Once the engine is returned to service, the maintenance event is considered done.

Major cylinder component means piston assembly, cylinder liner, connecting rod, or piston ring set.

MOD Director means Director of Manufacturers Operations Division, Office of Mobile Sources—Office of Air and Radiation of the Environmental Protection Agency.

Office Director means the Director for the Office of Mobile Sources—Office of Air and Radiation of the Environmental Protection Agency or an authorized representative of the Office Director.

Operator means transit authority, state, city department, or private or public entity controlling the use of one or more urban buses.

Original engine configuration means the engine configuration at time of initial sale.

Original equipment part means a part present in or on an engine at the time an urban bus is originally sold to the ultimate purchaser.

Scheduled maintenance means those maintenance events required by the equipment certifier in order to ensure that the retrofitted engine will maintain its emissions performance over the in-use compliance period.

Urban bus has the meaning set forth in §86.091-2 of this chapter.

Written instructions for proper maintenance and use means those maintenance and operation instructions specified in the warranty as being necessary to assure compliance of the retrofit/rebuild equipment with applicable emission standards for the in-use compliance period.