The following definitions apply to this part. Any terms not defined in this section have the meaning given in the Clean Air Act (42 U.S.C. §§ 7401–7671q). The definitions follow:

Aircraft has the meaning given in 14 CFR 1.1, a device that is used or intended to be used for flight in the air.

Aircraft engine means a propulsion engine that is installed on or that is manufactured for installation on an airplane for which certification under 14 CFR chapter I is sought.

Aircraft gas turbine engine means a turboprop, turbojet, or turbofan aircraft engine.

Airplane has the meaning given in 14 CFR 1.1, an engine-driven fixed-wing aircraft heavier than air, that is supported in flight by the dynamic reaction of the air against its wings.

Characteristic level has the meaning given in Appendix 6 of ICAO Annex 16 (incorporated by reference, see § 1031.210). The characteristic level is a calculated emission level for each pollutant based on a statistical assessment of measured emissions from multiple tests.

Date of manufacture means the date on which a manufacturer is issued documentation by FAA (or other recognized airworthiness authority for engines certificated outside the United States) attesting that the given engine conforms to all applicable requirements. This date may not be earlier than the date on which engine assembly is complete. Where the manufacturer does not obtain such documentation from FAA (or other recognized airworthiness authority for engines certificated outside the United States), date of manufacture means the date of final engine assembly.

Derivative engine for emissions certification purposes means an engine that is derived from and similar in type design to an engine that has a type certificate issued in accordance with 14 CFR part 33, and complies with the requirements of § 1031.130.

Designated EPA Program Officer means the Director of the Assessment and Standards Division, 2000 Traverwood Drive, Ann Arbor, Michigan 48105.

Emission index means the quantity of pollutant emitted per unit of fuel mass used.

Engine model means an engine manufacturer’s designation for an engine grouping of engines and/or engine sub-models within a single engine type certificate family, where such engines have similar design, including being similar with respect to the core engine and combustor designs.

Engine sub-model means a designation for a grouping of engines with essentially identical design, especially with respect to the core engine and combustor designs and other emission-related features. Engines from an engine sub-model must be contained within a single engine model. For purposes of this part, an original engine model configuration is considered a sub-model. For example, if a manufacturer initially produces an engine model designated ABC and later introduces a new sub-model ABC-1, the engine model consists of two sub-models: ABC and ABC-1.

Engine type certificate family means a group of engines (comprising one or more engine models, including sub-models and derivative engines for emissions certification purposes of those engine models) determined by FAA to have a sufficiently common design to be grouped together under a type certificate.

EPA means the U.S. Environmental Protection Agency.

Except means to routinely allow engines to be manufactured and sold that do not meet (or do not fully meet) otherwise applicable standards. Note that this definition applies only with respect to § 1031.20 and that the term “except” has its plain meaning in other contexts.

Exempt means to allow, through a formal case-by-case process, an engine to be certificated and sold that does not meet the applicable standards of this part.

Exhaust emissions means substances emitted to the atmosphere from exhaust discharge nozzles, as measured by the test procedures specified in § 1031.140.

FAA means the U.S. Department of Transportation, Federal Aviation Administration.

Good engineering judgment involves making decisions consistent with generally accepted scientific and engineering principles and all relevant information, subject to the provisions of 40 CFR 1068.5.

ICAO Annex 16 means Volume II of Annex 16 to the Convention on International Civil Aviation (see § 1031.210 for availability).

New means relating to an aircraft or aircraft engine that has never been placed into service.

Non-volatile particulate matter (nvPM) means emitted particles that exist at a gas turbine engine exhaust nozzle exit plane that do not volatilize when heated to a temperature of 350 °C.

Rated output (rO) means the maximum power or thrust available for takeoff at standard day conditions as approved for the engine by FAA, including reheat contribution where applicable, but excluding any contribution due to water injection. Rated output is expressed in kilowatts for turboprop engines and in kilonewtons for turbojet and turbofan engines to at least three significant figures.

Rated pressure ratio (rPR) means the ratio between the combustor inlet pressure and the engine inlet pressure achieved by an engine operating at rated output, expressed to at least three significant figures.

Round has the meaning given in 40 CFR 1065.1001.

Smoke means the matter in exhaust emissions that obscures the transmission of light, as measured by the test procedures specified in § 1031.140.

Smoke number means a dimensionless value quantifying smoke emissions as calculated according to ICAO Annex 16.

Spare engine means an engine installed (or intended to be installed) on an in-use aircraft to replace an existing engine. See § 1031.20.

Standard day conditions means the following ambient conditions: temperature = 15 °C, specific humidity = 0.00634 kg H2O/kg dry air, and pressure = 101.325 kPa.

Subsonic means relating to an aircraft that has not been certificated under 14 CFR chapter I to exceed Mach 1 in normal operation.

Supersonic airplane means an airplane for which the maximum operating limit speed exceeds a Mach number of 1.

System losses means the loss of particles during transport through a sampling or measurement system component or due to instrument performance. Sampling and measurement system loss is due to various deposition mechanisms, some of which are particle-size dependent. Determining an engine’s actual emission rate depends on correcting for system losses in the nvPM measurement.

Turbofan engine means a gas turbine engine designed to create its propulsion from exhaust gases and from air that bypasses the combustion process and is accelerated in a ducted space between the inner (core) engine case and the outer engine fan casing.

Turbojet engine means a gas turbine engine that is designed to create its propulsion entirely from exhaust gases.

Turboprop engine means a gas turbine engine that is designed to create most of its propulsion from a propeller driven by a turbine, usually through a gearbox.

Turboshaft engine means a gas turbine engine that is designed to drive a rotor transmission system or a gas turbine engine not used for propulsion.

We (us, our) means the EPA Administrator and any authorized representatives.