§ 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]