§ 87.23 - Exhaust emission standards for Tier 6 and Tier 8 engines.

§ 87.23 Exhaust emission standards for Tier 6 and Tier 8 engines.

This section describes the emission standards that apply for Tier 6 and Tier 8 engines. The standards of this section apply for aircraft engines manufactured on or after July 18, 2012, except where we specify that they apply differently by year, or where the engine is exempt from one or more standards of this section. Except as specified in paragraph (d) of this section, these standards apply based on the date the engine is manufactured. 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 § 87.60. The tier of standards identified for an engine relates to NO_X emissions and that the specified standards for HC, CO, and smoke emissions apply independent of the changes to the NO_X emission standards.

(a) New turboprop aircraft engines with rated output at or above 1,000 kilowatts must comply with a smoke standard of 187 · rO^−0.168.

(b) New supersonic engines must comply with the standards shown in the following table:

Table 1 to § 87.23 - Smoke and Gaseous Emission Standards for New Supersonic Engines

Rated output	Smoke number	HC (g/kN rated output)	NOX (g/kN rated output)	CO (g/kN rated output)
rO <26.7 kN		140 · 0.92rPR	36 + 2.42 · rPR	4550 · rPR−1.03
rO ≥26.7 kN	83.6 · rO−0.274 or 50.0, whichever is smaller	140 · 0.92rPR	36 + 2.42 · rPR	4550 · rPR−1.03

(c) New turbofan or turbojet aircraft engines that are installed in subsonic aircraft must comply with the following standards:

(1) The applicable smoke, HC, and CO standards are shown in the following table:

Table 2 to § 87.23 - Smoke, HC, and CO Standards for New Subsonic Turbofan or Turbojet Engines

Rated output (kN)	Smoke standard	Gaseous emission standards (g/kN rated output)
		HC	CO
rO <26.7 kN	83.6 · rO−0.274 or 50.0, whichever is smaller
rO ≥26.7 kN	83.6 · rO−0.274 or 50.0, whichever is smaller	19.6	118

(2) The Tier 6 NO_X standards apply as described in this paragraph (c)(2). See paragraph (d) of this section for provisions related to models introduced before these standards started to apply and engines determined to be derivative engines for emissions certification purposes under the requirements of this part.

Table 3 to § 87.23 - Tier 6 NO_X Standards for New Subsonic Turbofan or Turbojet Engines With Rated Output Above 26.7 kN

If the rated pressure ratio is -	and the rated output (in kN) is -	The NOX emission standard (in g/kN rated output) is -
rPR ≤30	26.7 <rO ≤89	38.5486 + 1.6823·rPR − 0.2453·rO − 0.00308·rPR·rO
	rO >89	16.72 + 1.4080·rPR
30 <rPR <82.6	26.7 <rO ≤89	46.1600 + 1.4286·rPR − 0.5303·rO + 0.00642·rPR·rO
	rO >89	−1.04 + 2.0·rPR
rPR ≥82.6	all	32 + 1.6·rPR

(3) The Tier 8 NO_X standards apply as described in this paragraph (c)(3) beginning January 1, 2014. See paragraph (d) of this section for provisions related to models introduced before January 1, 2014 apply and engines determined to be derivative engines for emissions certification purposes under the requirements of this part.

Table 4 to § 87.23 - Tier 8 NO_X Standards for New Subsonic Turbofan or Turbojet Engines With Rated Output Above 26.7 kN

If the rated pressure ratio is -	and the rated output (in kN) is -	The NOX emission standard (in g/kN rated output) is -
rPR ≤30	26.7 <rO ≤89	40.052 + 1.5681·rPR − 0.3615·rO − 0.0018·rPR·rO
	rO >89	7.88 + 1.4080·rPR
30 <rPR <104.7	26.7 <rO ≤89	41.9435 + 1.505·rPR − 0.5823·rO + 0.005562·rPR·rO
	rO >89	−9.88 + 2.0·rPR
rPR ≥104.7	all	32 + 1.6·rPR

(d) This paragraph (d) specifies phase-in provisions that allow continued production of certain engines after the Tier 6 and Tier 8 standards begin to apply.

(1) Engine type certificate families certificated with characteristic levels at or below the Tier 4 NO_X standards of § 87.21 (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 Tier 6 NO_X standards of paragraph (c)(2) of this section. This also applies for engines that are covered by the same type certificate and are determined to be derivative engines for emissions certification purposes under the requirements of this part. Note that after this production cutoff date for the Tier 6 NO_X standards, such engines may be produced only if they are covered by an exemption under § 87.50. This production cutoff does not apply to engines installed (or delivered for installation) on military aircraft.

(2) Engine type certificate families certificated with characteristic levels at or below the Tier 6 NO_X standards of paragraph (c)(2) of this section with an introduction date before January 1, 2014 may continue to be produced. This also applies for engines that are covered by the same type certificate and are determined to be derivative engines for emissions certification purposes under the requirements of this part.

(3) An engine manufacturer may produce up to six newly manufactured Tier 4 engines on or after July 18, 2012, subject to the provisions of this paragraph (d)(3). Tier 4 engines meeting the criteria of this paragraph (d)(3) are excepted without request from the otherwise applicable Tier 6 NO_X emission standard. To be eligible for this exception the engines must have a date of manufacture prior to August 31, 2013 and be fully compliant with all requirements applicable to Tier 4 engines. The manufacturer must include these engines in the report required by § 87.50. This exception is void for any manufacturer that produces more than six excepted engines under this paragraph.

[77 FR 36382, June 18, 2012, as amended at 77 FR 65823, Oct. 31, 2012]