745 

Federal Aviation Administration, DOT 

§ 34.1 

applicable requirements. Engines ex-
cepted with respect to certain stand-
ards must comply with other standards 
from which they are not specifically 
excepted. 

Exempt 

means an engine that does 

not meet certain applicable standards 
but may be produced and sold under 
the terms allowed by a grant of exemp-
tion issued pursuant to § 34.7 of this 
part and part 11 of this chapter. Ex-
empted engines must conform to regu-
latory conditions specified in the ex-
emption as well as other applicable 
regulations. Exempted engines are sub-
ject to the standards of this part even 
though they are not required to comply 
with the otherwise applicable require-
ments. Engines exempted with respect 
to certain standards must comply with 
other standards as a condition of the 
exemption. 

Exhaust emissions 

means substances 

emitted into the atmosphere from the 
exhaust discharge nozzle of an aircraft 
or aircraft engine. 

Fuel venting emissions 

means raw fuel, 

exclusive of hydrocarbons in the ex-
haust emissions, discharged from air-
craft gas turbine engines during all 
normal ground and flight operations. 

In-use aircraft gas turbine engine 

means an aircraft gas turbine engine 
which is in service. 

Introduction date 

means the date of 

manufacture of the first individual pro-
duction engine of a given engine model 
or engine type certificate family to be 
certificated. Neither test engines nor 
engines not placed into service affect 
this date. 

New aircraft turbine engine 

means an 

aircraft gas turbine engine which has 
never been in service. 

Power setting 

means the power or 

thrust output of an engine in terms of 
kilonewtons thrust for turbojet and 
turbofan engines or shaft power in 
terms of kilowatts for turboprop en-
gines. 

Rated output (rO) 

means the max-

imum power/thrust available for take-
off at standard day conditions as ap-
proved for the engine by the Federal 
Aviation Administration, including re-
heat contribution where applicable, but 
excluding any contribution due to 
water injection, expressed in kilowatts 

or kilonewtons (as applicable), rounded 
to at least three significant figures. 

Rated pressure ratio (rPR) 

means the 

ratio between the combustor inlet pres-
sure and the engine inlet pressure 
achieved by an engine operation at 
rated output, rounded to at least three 
significant figures. 

Reference day conditions 

means the 

reference ambient conditions to which 
the gaseous emissions (HC and smoke) 
are to be corrected. The reference day 
conditions are as follows: Temperature 
= 15 

°

C, specific humidity = 0.00629 kg 

H

2

O/kg of dry air, and pressure = 101325 

Pa. 

Sample system 

means the system 

which provides for the transportation 
of the gaseous emission sample from 
the sample probe to the inlet of the in-
strumentation system. 

Shaft power 

means only the measured 

shaft power output of a turboprop en-
gine. 

Smoke 

means the matter in exhaust 

emissions which obscures the trans-
mission of light. 

Smoke number (SN) 

means the 

dimensionless term quantifying smoke 
emissions. 

Standard day conditions 

means the 

following ambient conditions: tempera-
ture = 15 

°

C, specific humidity = 0.00634 

kg H

2

O/kg dry air, and pressure = 

101.325 kPa. 

Taxi/idle (in) 

means those aircraft op-

erations involving taxi and idle be-
tween the time of landing roll-out and 
final shutdown of all propulsion en-
gines. 

Taxi/idle (out) 

means those aircraft 

operations involving taxi and idle be-
tween the time of initial starting of 
the propulsion engine(s) used for the 
taxi and the turn onto the duty run-
way. 

Tier, 

as used in this part, is a des-

ignation related to the NO

X

emission 

standard for the engine as specified in 
§ 34.21 or § 34.23 of this part (e.g., Tier 0). 

[Doc. No. 25613, 55 FR 32861, Aug. 10, 1990; 55 
FR 37287, Sept. 10, 1990, as amended by Amdt. 
34–3, 64 FR 5558, Feb. 3, 1999; Amdt. 34–5, 77 
FR 76849, Dec. 31, 2012; Amdt. 34–5A, 78 FR 
63016, Oct. 23, 2013] 

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