Regulations last checked for updates: May 14, 2024

Title 40 - Protection of Environment last revised: May 10, 2024
§ 1031.60 - Subsonic turbojet and turbofan engines above 26.7 kN thrust.

The following standards apply to new turbofan or turbojet aircraft engines with rated output above 26.7 kN thrust that are installed in subsonic aircraft:

(a) Smoke. (1) Tier 0. Except as specified in (a)(2) of this section, engines of a type or model with rated output at or above 129 kN, and for which the date of manufacture of the individual engine after January 1, 1976 and is before January 1, 1984 may not have a characteristic level for smoke number exceeding the following emission standard:

SN = 83.6·rO 0.274

(2) JT8D and JT3D engines. (i) Engines of the type JT8D for which the date of manufacture of the individual engine is on or after February 1, 1974, and before January 1, 1984 may not have a characteristic level for smoke number exceeding an emission standard of 30.

(ii) Engines of the type JT3D for which the date of manufacture of the individual engine is on or after January 1, 1978 and before January 1, 1984 may not have a characteristic level for smoke number exceeding an emission standard of 25.

(3) Tier 0 in-use. Except for engines of the type JT8D and JT3D, in-use engines with rated output at or above 129 kN thrust may not exceed the following smoke number standard:

SN = 83.6·rO 0.274

(4) JT8D in-use. In-use aircraft engines of the type JT8D may not exceed a smoke number standard of 30.

(5) Tier 1. Engines of a type or model for which the date of manufacture of the individual engine is on or after January 1, 1984 and before January 1, 2023 may not have a characteristic level for smoke number exceeding an emission standard that is the lesser of 50 or the following:

SN = 83.6·rO 0.274

(6) Tier 10. Engines of a type or model for which the date of manufacture of the individual engine is on or after January 1, 2023 may not have a characteristic level for the maximum nvPM mass concentration in µg/m 3 exceeding the following emission standard:

nvPMMC = 10(3 + 2.9 * rO^−0.274)

(b) LTO nvPM mass and number. An engine's characteristic level for nvPM mass and nvPM number may not exceed emission standards as follows:

(1) Tier 11 new type. The following emission standards apply to engines of a type or model for which an application for original type certification is submitted on or after January 1, 2023 and for engines covered by an earlier type certificate if they do not qualify as derivative engines for emission purposes as described in § 1031.130:

Table 1 to § 1031.60(b)(1)—Tier 11 New Type nvPM Standards

Rated output (rO)
in kN
nvPMmass
in milligrams/kN
nvPMnum
in particles/kN
26.7 < rO ≤ 1501251.1−6.914·rO1.490·10 16−8.080·10 13·rO
rO > 150214.02.780·10 15

(2) Tier 11 in-production. The following emission standards apply to engines of a type or model for which the date of manufacture of the individual engine is on or after January 1, 2023:

Table 2 to § 1031.60(b)(2)—Tier 11 In-Production nvPM Standards

Rated output (rO)
in kN
nvPMmass
in milligrams/kN
nvPMnum
in particles/kN
26.7 < rO ≤ 2004646.9−21.497·rO2.669·10 16−1.126·10 14·rO
rO > 200347.54.170·10 15

(c) HC. Engines of a type or model for which the date of manufacture of the individual engine is on or after January 1, 1984, may not have a characteristic level for HC exceeding an emission standard of 19.6 g/kN.

(d) CO. Engines of a type or model for which the date of manufacture of the individual engine is on or after July 7, 1997, may not have a characteristic level for CO exceeding an emission standard of 118 g/kN.

(e) NOX. An engine's characteristic level for NOX may not exceed emission standards as follows:

(1) Tier 0. The following NOX emission standards apply to engines of a type or model for 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 after December 31, 1999, and before December 31, 2003:

NOX = 40+2·rPR g/kN

(2) Tier 2. The following NOX emission standards apply to engines of a type or model for 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 on or after December 31, 1999, and before December 31, 2003:

NOX = 32+1.6·rPR g/kN

(3) Tier 4 new type. The following NOX emission standards apply to engines of a type or model for which the date of manufacture of the first individual production model was after December 31, 2003, and before July 18, 2012:

Table 3 to § 1031.60(e)(3)—Tier 4 New Type NOX Standards

If the rated pressure
ratio (rPR) is—
and the rated
output (kN) is—
the NOX emission standard (g/kN) is—
(i) rPR ≤ 30(A) 26.7 < rO ≤ 8937.572 + 1.6·rPR−0.2087·rO
(B) rO > 8919 + 1.6·rPR
(ii) 30 < rPR < 62.5(A) 26.7 < rO ≤ 8942.71 + 1.4286·rPR−0.4013·rO + 0.00642·rPR·rO
(B) rO > 897 + 2·rPR
(iii) rPR ≥ 82.6All32 + 1.6·rPR

(4) Tier 6 in-production. The following NOX emission standards apply to engines of a type or model for which the date of manufacture of the individual engine is on or after July 18, 2012:

Table 4 to § 1031.60(e)(4)—Tier 6 In-Production NOX Standards

If the rated pressure
ratio (rPR) is—
and the rated
output (kN) is—
the NOX emission standard (g/kN) is—
(i) rPR ≤ 30(A) 26.7 < rO ≤ 8938.5486 + 1.6823·rPR−0.2453·rO − 0.00308·rPR·rO
(B) rO > 8916.72 + 1.4080·rPR
(ii) 30 < rPR < 82.6(A) 26.7 < rO ≤ 8946.1600 + 1.4286·rPR−0.5303·rO + 0.00642·rPR·rO
(B) rO > 89−1.04 + 2.0·rPR
(iii) rPR ≥ 82.6All32 + 1.6·rPR

(5) Tier 8 new type. The following NOX standards apply to engines of a type or model for which the date of manufacture of the first individual production model was on or after January 1, 2014; or for which an application for original type certification is submitted on or after January 1, 2023; or for engines covered by an earlier type certificate if they do not qualify as derivative engines for emission purposes as described in § 1031.130:

Table 5 to § 1031.60(e)(5)—Tier 8 New Type NOX Standards

If the rated pressure
ratio (rPR) is—
and the rated
output (kN) is—
the NOX emission standard (g/kN) is—
(i) rPR ≤ 30(A) 26.7 < rO ≤ 8940.052 + 1.5681·rPR−0.3615·rO−0.0018·rPR·rO
(B) rO > 897.88 + 1.4080·rPR
(ii) 30 < rPR < 104.7(A) 26.7 < rO ≤ 8941.9435 + 1.505·rPR−0.5823·rO + 0.005562·rPR·rO
(B) rO > 89−9.88 + 2.0·rPR
(iii) rPR ≥ 104.7All32 + 1.6·rPR
source: 87 FR 72351, Nov. 23, 2022, unless otherwise noted.
cite as: 40 CFR 1031.60