Section 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 [MICRO]g/m3 . 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 [MICRO]g/m3 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) | nvPM mass (mg/kN) | nvPM num (particles/kN) |
| TF, T3, T8 | 26.7 < rO [LESS THAN EQUAL TO] 200 | 4646.9 - 21.497 (rO) | 2.669 * 1016 - 1.126 * 1014 (rO). |
| rO > 200 | 347.5 | 4.170 * 1015 . |
(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) | nvPM mass (mg/kN) | nvPM num (particles/kN) |
| TF, T3, T8 | 26.7 < rO [LESS THAN EQUAL TO] 150 | 1251.1 - 6.914 (rO) | 1.490 * 1016 - 8.080 * 1013 (rO). |
| rO > 150 | 214.0 | 2.780 * 1015 . |
(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, 2024.89 FR 31087, 5/24/2024; 89 FR 37972, 5/24/2024