Regulations last checked for updates: Jun 02, 2024

Title 14 - Aeronautics and Space last revised: May 28, 2024
§ 34.20 - Applicability.

The provisions of this subpart are applicable to all aircraft gas turbine engines of the classes specified beginning on the dates specified in § 34.21.

§ 34.21 - Standards for exhaust emissions.

(a) Exhaust emissions of smoke from each new aircraft gas turbine engine of class T8 manufactured on or after February 1, 1974, shall not exceed a smoke number (SN) of 30.

(b) Exhaust emissions of smoke from each new aircraft gas turbine engine of class TF and of rated output of 129 kN (29,000 lb) thrust or greater, manufactured on or after January 1, 1976, shall not exceed

SN = 83.6 (rO) −0.274 (rO is in kN).

(c) Exhaust emission of smoke from each new aircraft gas turbine engine of class T3 manufactured on or after January 1, 1978, shall not exceed a smoke number (SN) of 25.

(d) Gaseous exhaust emissions from each new aircraft gas turbine engine shall not exceed:

(1) For Classes TF, T3, T8 engines greater than 26.7 kN (6,000 lb) rated output:

(i) Engines manufactured on or after January 1, 1984:

Hydrocarbons: 19.6 g/kN rO.

(ii) Engines manufactured on or after July 7, 1997:

Carbon Monoxide: 118 g/kN rO.

(iii) Engines of a type or model of which the date of manufacture of the first individual production model was on or before December 31, 1995, and for which the date of manufacture of the individual engine was on or before December 31, 1999 (Tier 2):

Oxides of Nitrogen: (40 + 2(rPR)) g/kN rO.

(iv) Engines of a type or model of which the date of manufacture of the first individual production model was after December 31, 1995, or for which the date of manufacture of the individual engine was after December 31, 1999 (Tier 2):

Oxides of Nitrogen: (32 + 1.6(rPR)) g/kN rO.

(v) The emission standards prescribed in paragraphs (d)(1)(iii) and (iv) of this section apply as prescribed beginning July 7, 1997.

(vi) The emission standards of this paragraph apply as prescribed after December 18, 2005. For engines of a type or model of which the first individual production model was manufactured after December 31, 2003 (Tier 4):

(A) That have a rated pressure ratio of 30 or less and a maximum rated output greater than 89 kN:

Oxides of Nitrogen: (19 + 1.6(rPR)) g/kN rO.

(B) That have a rated pressure ratio of 30 or less and a maximum rated output greater than 26.7 kN but not greater than 89 kN:

Oxides of Nitrogen: (37.572 + 1.6(rPR) − 0.2087(rO)) g/kN rO.

(C) That have a rated pressure ratio greater than 30 but less than 62.5, and a maximum rated output greater than 89 kN:

Oxides of Nitrogen: (7 + 2(rPR)) g/kN rO.

(D) That have a rated pressure ratio greater than 30 but less than 62.5, and a maximum rated output greater than 26.7 kN but not greater than 89 kN:

Oxides of Nitrogen: (42.71 + 1.4286(rPR) − 0.4013(rO) + 0.00642(rPR × rO)) g/kN rO.

(E) That have a rated pressure ratio of 62.5 or more:

Oxides of Nitrogen: (32 + 1.6(rPR)) g/kN rO.

(2) For Class TSS Engines manufactured on or after January 1, 1984:

Hydrocarbons: 140 (0.92) rPR g/kN rO.

(e) Smoke exhaust emissions from each gas turbine engine shall not exceed:

(1)(A) For Class TF of rated output less than 26.7 kN (6,000 lbf) manufactured on or after August 9, 1985, and before July 18, 2012:

SN = 83.6(rO)−0.274 (rO is in kN) not to exceed a maximum of SN = 50.

(B) For Classes TF, T3, and T8 of rated output less than 26.7 kN (6,000 lbf) manufactured on or after July 18, 2012, and before January 1, 2023:

SN = 83.6(rO)−0.274 or 50.0, whichever is smaller.

(C) For Classes TF, T3, and T8 of rated output of 26.7 kN (6,000 lbf) or less manufactured on or after January 1, 2023:

SN = 83.6(rO)−0.274 or 50.0, whichever is smaller.

(2) For Classes T3, T8, TSS, and TF of rated output greater than or equal to-26.7 kN (6,000 lbf) manufactured on or after January 1, 1984, and before January 1, 2023:

SN = 83.6(rO)−0.274 (rO is in kN) not to exceed a maximum of SN = 50.

(3) For Class TP of rated output equal to or greater than 1,000 kW manufactured on or after January 1, 1984:

SN = 187(rO)−0.168 (rO is in kW).

(4) For Class TSS manufactured on or after January 1, 2023:

SN = 83.6(rO)−0.274 (rO is in kN) not to exceed a maximum of SN = 50.

(f) The standards set forth in paragraphs (a), (b), (c), (d), and (e) of this section refer to a composite gaseous emission sample representing the operation cycles and exhaust smoke emission emitted during operation of the engine as specified in the applicable sections of subpart G of this part, and measured and calculated in accordance with the procedures set forth in subpart G.

(g) Where a gaseous emission standard is specified by a formula, calculate and round the standard to three significant figures or to the nearest 0.1 g/kN (for standards at or above 100 g/kN). Where a smoke standard is specified by a formula, calculate and round the standard to the nearest 0.1 SN. Engines comply with an applicable standard if the testing results show that the engine type certificate family's characteristic level does not exceed the numerical level of that standard, as described in § 34.60.

[Doc. No. 25613, 55 FR 32861, Aug. 10, 1990; 55 FR 37287, Sept. 10, 1990, as amended by Amdt. 34-3, 64 FR 5559, Feb. 3, 1999; Amdt. 34-4, 74 FR 19127, Apr. 28, 2009; Amdt. 34-5, 77 FR 76851, Dec. 31, 2012; Amdt. No. 34-7, 89 FR 31087, Apr. 24, 2024]
§ 34.23 - Exhaust Emission Standards for Engines Manufactured on and after July 18, 2012.

The standards of this section apply to aircraft engines manufactured on and after July 18, 2012, unless otherwise exempted or excepted. Where a gaseous emission standard is specified by a formula, calculate and round the standard to three significant figures or to the nearest 0.1 g/kN (for standards at or above 100 g/kN). Where a smoke standard is specified by a formula, calculate and round the standard to the nearest 0.1 SN. Engines comply with an applicable standard if the testing results show that the engine type certificate family's characteristic level does not exceed the numerical level of that standard, as described in § 34.60.

(a) Gaseous exhaust emissions from each new aircraft gas turbine engine shall not exceed:

(1) [Reserved]

(2) Except as provided in §§ 34.9(b) and 34.21(c), for Classes TF, T3 and T8 engines manufactured on and after July 18, 2012, and for which the first individual production model was manufactured on or before December 31, 2013 (Tier 6):

Tier 6 Oxides of Nitrogen Emission Standards for Subsonic Engines

Class Rated pressure ratio—rPR Rated output rO
(kN)
NOX
(g/kN)
TF, T3, T8rPR ≤ 3026.7 < rO ≤ 89.038.5486 + 1.6823 (rPR) − 0.2453 (rO) − (0.00308 (rPR) (rO)).
rO > 89.016.72 + 1.4080 (rPR).
30 < rPR < 82.626.7 < rO ≤ 89.046.1600 + 1.4286 (rPR) − 0.5303 (rO) + (0.00642 (rPR) (rO)).
rO > 89.0−1.04 + 2.0 (rPR).
rPR ≥ 82.6rO 26.732 + 1.6 (rPR).

(3) Engines exempted from paragraph (a)(2) of this section produced on or before December 31, 2016 must be labeled “EXEMPT NEW” in accordance with § 45.13 of this chapter. No exemptions to the requirements of paragraph (a)(2) of this section will be granted after December 31, 2016.

(4) For Class TSS Engines manufactured on and after July 18, 2012:

Gaseous Emission Standards for Supersonic Engines

Class Rated output
rO 1 (kN)
NOX
(g/kN)
CO
(g/kN)
TSSAll36 + 2.42 (rPR)4,550 (rPR) −1.03

1 rO is the rated output with afterburning applied.

(b) Gaseous exhaust emissions from each new aircraft gas turbine engine shall not exceed:

(1) For Classes TF, T3 and T8 engines of a type or model of which the first individual production model was manufactured after December 31, 2013 (Tier 8):

Tier 8 Oxides of Nitrogen Emission Standards for Subsonic Engines

Class Rated pressure ratio—rPR Rated output rO
(kN)
NOX
(g/kN)
TF, T3, T8rPR ≤ 3026.7 < rO ≤ 89.040.052 + 1.5681 (rPR) − 0.3615 (rO) − (0.0018 (rPR) (rO)).
rO > 89.07.88 + 1.4080 (rPR).
30 < rPR < 104.726.7 < rO ≤ 89.041.9435 + 1.505 (rPR) − 0.5823 (rO) + (0.005562 (rPR) (rO)).
rO > 89.0−9.88 + 2.0 (rPR).
rPR ≥ 104.7rO ≥ 26.732 + 1.6 (rPR).

(c) Engines (including engines that are determined to be derivative engines for the purposes of emission certification) type certificated with characteristic levels at or below the NOX standards of § 34.21(d)(1)(vi) of this part (as applicable based on rated output and rated pressure ratio) and introduced before July 18, 2012, may be produced through December 31, 2012, without meeting the NOX standard of paragraph (a)(2) of this section.

[Doc. No. 34-5, 77 FR 76851, Dec. 31, 2012, as amended by Amdt. 34-5A, 78 FR 63017, Oct. 23, 2013; 78 FR 65554, Nov. 1, 2013; Amdt. No. 34-7, 89 FR 31087, Apr. 24, 2024]
§ 34.25 - Non-volatile particulate emissions standards (nvPM).

The standards of this section apply to an aircraft engine of Class TF, T3, or T8 with a rated output greater than 26.7 kN that is manufactured after January 1, 2023. Where a maximum nvPMMC standard is expressed as a formula, calculate and round the standard to the nearest 1.0 µg/m 3. Where an nvPMmass standard is expressed as a formula, calculate and round the standard to three significant figures or to the nearest 0.1 mg/kN. Where an nvPMnum standard is expressed as a formula, calculate and round the standard to three significant figures. Engines comply with an applicable standard if the test results show that the engine type certificate family's characteristic level does not exceed the numerical level of the nvPM standard when tested as described in subpart H of this part.

(a) Except as provided in paragraph (b) or (c) of this section;

(1) The characteristic level for the maximum nvPMMC expressed in units of µg/m 3 must not exceed the following:

nvPMMC = 10(3+2.9r0-0.274) and

(2) The characteristic level for nvPM mass expressed in [mg/kN] and for nvPM number expressed in [particles/kN] must not exceed the following:

Table 1 to Paragraph (a)(2)

Class Rated output
(rO)
(kN)
nvPMmass
(mg/kN)
nvPMnum
(particles/kN)
TF, T3, T826.7 < rO ≤ 2004646.9 − 21.497 (rO)2.669 × 10 16 − 1.126 × 10 14 (rO).
rO > 200347.54.170 × 10 15.

(b) For a change in type design by the type design holder, when the application for an amended type certificate is filed after January 1, 2023:

(1) If the engine qualifies as a derivative engine in accordance with § 34.48 of this part, no testing is required for the engine to use the same nvPM certificated parameters (nvPMmass, nvPMnum, and maximum nvPMMC) as the engine it is derived from; or

(2) If the engine does not qualify as a derivative engine in accordance with § 34.48 of this part, the applicant must demonstrate compliance with each requirement in paragraph (a) of this section.

(c) For issuance of an original type certificate when an application for type certification is filed after January 1, 2023, the applicant must demonstrate that the engine does not exceed:

(1) For maximum nvPMMC: as prescribed in paragraph (a)(1) of this section; and

(2) For the characteristic level for nvPMmass expressed in units of [mg/kN], and for nvPMnum expressed in units of [particles/kN], the following:

Table 2 to Paragraph (c)(2)

Class Rated output
(rO)
(kN)
nvPMmass
(mg/kN)
nvPMnum
(particles/kN)
TF, T3, T826.7 < rO ≤ 1501251.1 − 6.914 (rO)1.490 × 10 16 − 8.080 × 10 13 (rO).
rO > 150214.02.780 × 10 15.

(d) For engines type certificated after January 1, 2023 and prior to May 24, 2024, compliance with this part must be demonstrated no later than August 22, 2024.

[Doc. No. FAA-2023-2434, Amdt. No. 34-7, 89 FR 31087, Apr. 24, 2024, as amended by Amdt. No. 34-7A, 89 FR 37972, May 7, 2024]
authority: 42 U.S.C. 4321
source: Docket No. 25613, 55 FR 32861, Aug. 10, 1990, unless otherwise noted.
cite as: 14 CFR 34.23