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752 

14 CFR Ch. I (1–1–24 Edition) 

§ 34.20 

Subpart C—Exhaust Emissions 

(New Aircraft Gas Turbine En-
gines) 

§ 34.20

Applicability. 

The provisions of this subpart are ap-

plicable to all aircraft gas turbine en-
gines of the classes specified beginning 
on the dates specified in § 34.21. 

§ 34.21

Standards for exhaust emis-

sions. 

(a) Exhaust emissions of smoke from 

each new aircraft gas turbine engine of 
class T8 manufactured on or after Feb-
ruary 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, manufac-
tured 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 Jan-
uary 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 De-
cember 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 indi-

vidual 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 De-
cember 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 out-
put 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 out-
put greater than 26.7 kN but not great-
er 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 manufac-

tured on or after January 1, 1984: 

Hydrocarbons: 140 (0.92)

rPR

g/kN rO. 

(e) Smoke exhaust emissions from 

each gas turbine engine of the classes 
specified below shall not exceed: 

(1) For Class TF of rated output less 

than 26.7 kN (6,000 lb) manufactured on 
or after August 9, 1985: 

SN = 83.6(rO)

¥

0.274

(rO is in kN) not to 

exceed a maximum of SN = 50. 

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753 

Federal Aviation Administration, DOT 

§ 34.23 

(2) For Classes T3, T8, TSS, and TF of 

rated output equal to or greater than 
26.7 kN (6,000 lb) manufactured on or 
after January 1, 1984: 

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 man-
ufactured on or after January 1, 1984: 

SN = 187(rO)

¥

0.168

(rO is in kW). 

(f) The standards set forth in para-

graphs (a), (b), (c), (d), and (e) of this 
section refer to a composite gaseous 
emission sample representing the oper-
ation cycles and exhaust smoke emis-
sion 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 sub-
part G. 

(g) Where a gaseous emission stand-

ard is specified by a formula, calculate 
and round the standard to three signifi-
cant 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 en-
gine type certificate family’s char-
acteristic level does not exceed the nu-
merical level of that standard, as de-
scribed 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] 

§ 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 for-
mula, 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 stand-
ard is specified by a formula, calculate 
and round the standard to the nearest 
0.1 SN. Engines comply with an appli-
cable 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) For Classes TF, T3 and T8 of rated 

output less than 26.7 kN (6,000 lb) man-
ufactured on and after July 18, 2012: 

SN = 83.6(rO)

¥

0.274

or 50.0, whichever is 

smaller 

(2) Except as provided in §§ 34.9(b) and 

34.21(c), for Classes TF, T3 and T8 en-
gines manufactured on and after July 
18, 2012, and for which the first indi-
vidual production model was manufac-
tured on or before December 31, 2013 
(Tier 6): 

T

IER

6 O

XIDES OF

N

ITROGEN

E

MISSION

S

TANDARDS FOR

S

UBSONIC

E

NGINES

 

Class 

Rated pressure ratio— 

rPR 

Rated output rO 

(kN) 

NO

X

 

(g/kN) 

TF, T3, T8 .....................

rPR 

≤ 

30 .......................

26.7 < rO 

≤ 

89.0 ...........

38.5486 + 1.6823 (rPR) 

¥ 

0.2453 (rO) 

¥ 

(0.00308 (rPR) (rO)). 

rO > 89.0 ......................

16.72 + 1.4080 (rPR). 

30 < rPR < 82.6 ...........

26.7 < rO 

≤ 

89.0 ...........

46.1600 + 1.4286 (rPR) 

¥ 

0.5303 (rO) + 

(0.00642 (rPR) (rO)). 

rO > 89.0 ......................

¥

1.04 + 2.0 (rPR). 

rPR 

≥ 

82.6 ....................

rO 

≥ 

26.7 ......................

32 + 1.6 (rPR). 

(3) Engines exempted from paragraph 

(a)(2) of this section produced on or be-

fore December 31, 2016 must be labeled 
‘‘EXEMPT NEW’’ in accordance with 

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