817 

Federal Aviation Administration, DOT 

Pt. 36, App. H 

(Secs. 313(a), 603, and 611(b), Federal Aviation 
Act of 1958 as amended (49 U.S.C. 1354(a), 
1423, and 1431(b)); sec. 6(c), Department of 
Transportation Act (49 U.S.C. 1655 (c)); Title 
I, National Environmental Policy Act of 1969 
(42 U.S.C. 4321 

et seq.

); E. O. 11514, March 5, 

1970 and 14 CFR 11.45). 

[Amdt. 36–16, 53 FR 47400, Nov. 22, 1988; 53 FR 
50157, Dec. 13, 1988, as amended by Amdt. 36– 
22, 64 FR 55602, Oct. 13, 1999; Amdt. 36–54, 67 
FR 45236, July 8, 2002; Amdt. 36–27, 70 FR 
45504, Aug. 5, 2005; Amdt. 36–28, 71 FR 532, 
Jan. 4, 2006; FAA Doc. No. FAA–2015–3782, 
Amdt. No. 36–31, 82 FR 46131, Oct. 4, 2017] 

A

PPENDIX

H 

TO

P

ART

36—N

OISE

R

E

-

QUIREMENTS

F

OR

H

ELICOPTERS

 

U

NDER

S

UBPART

H 

PART A

—

REFERENCE CONDITIONS

 

Sec. 

H36.1 

General. 

H36.3 

Reference Test Conditions. 

H36.5 

Symbols and Units. 

PART B

—

NOISE MEASUREMENT UNDER

§ 36.801 

H36.101 

Noise certification test and measurement 

conditions. 

H36.103 

Takeoff test conditions. 

H36.105 

Flyover test conditions. 

H36.107 

Approach test conditions. 

H36.109 

Measurement of helicopter noise re-

ceived on the ground. 

H36.111 

Reporting and correcting measured 

data. 

H36.113 

Atmospheric attenuation of sound. 

PART C

—

NOISE EVALUATION AND CALCULATION

 

UNDER

§ 36.803 

H36.201 

Noise evaluation in EPNdB. 

H36.203 

Calculation of noise levels. 

H36.205 

Detailed data correction procedures. 

PART D

—

NOISE LIMITS UNDER

§ 36.805 

H36.301 

Noise measurement, evaluation, and cal-

culation. 

H36.303 [Reserved] 
H36.305 

Noise levels. 

PART A

—

REFERENCE CONDITIONS

 

Section H36.1 General. 

This appendix pre-

scribes noise requirements for helicopters 
specified under § 36.1, including: 

(a) The conditions under which helicopter 

noise certification tests under Part H must 
be conducted and the measurement proce-
dures that must be used under § 36.801 to 
measure helicopter noise during each test; 

(b) The procedures which must be used 

under § 36.803 to correct the measured data to 
the reference conditions and to calculate the 
noise evaluation quantity designated as Ef-
fective Perceived Noise Level (EPNL); and 

(c) The noise limits for which compliance 

must be shown under § 36.805. 

Section H36.3 Reference Test Conditions. 

(a) 

Meteorological conditions. 

Aircraft posi-

tion, performance data and noise measure-
ments must be corrected to the following 
noise certification reference atmospheric 
conditions which shall be assumed to exist 
from the surface to the aircraft altitude: 

(1) Sea level pressure of 2,116 psf (1,013.25 

hPa). 

(2) Ambient temperature of 77 degrees F (25 

degrees C). 

(3) Relative humidity of 70 percent. 
(4) Zero wind. 
(b) 

Reference test site. 

The reference test 

site is flat and without line-of-sight obstruc-
tions across the flight path that encom-
passes the 10 dB down points. 

(c) 

Takeoff reference profile. 

(1) Figure H1 il-

lustrates a typical takeoff profile, including 
reference conditions. 

(2) The reference flight path is defined as a 

straight line segment inclined from the 
starting point (1,640 feet (500 meters) from 
the center microphone location and 65 feet 
(20 meters) above ground level) at a constant 
climb angle 

b 

defined by the certificated best 

rate of climb and V

y

for minimum engine 

performance. The constant climb angle 

b 

is 

derived from the manufacturer’s data (ap-
proved by the FAA) to define the flight pro-
file for the reference conditions. The con-
stant climb angle 

b 

is drawn through C

r

and 

continues, crossing over station A, to the po-
sition corresponding to the end of the type 
certification takeoff path represented by po-
sition I

r

. 

(d) 

Level flyover reference profile. 

The begin-

ning of the level flyover reference profile is 
represented by helicopter position D

r

(Figure 

H2). The helicopter approaches position D

r

in 

level flight 492 feet above ground level as 
measured at Station A. Reference airspeed 
must be either 0.9V

H

; 0.9V

NE

; 0.45V

H

+ 65 kts 

(0.45V

H

+ 120km/h); or 0.45V

NE

+ 65kts (0.45V

NE

 

+ 120 km/h), whichever of the four speeds is 
least. The helicopter crosses directly over-
head station A in level flight and proceeds to 
position J

r

. 

(e) For noise certification purposes, V

H

is 

defined as the airspeed in level flight ob-
tained using the minimum specified engine 
torque corresponding to maximum contin-
uous power available for sea level pressure of 
2,116 psf (1,013.25 hPa) at 77 

°

F (25 

°

C) ambient 

conditions at the relevant maximum certifi-
cated weight. The value of V

NE

is the never- 

exceed airspeed. The values of V

H

and V

NE

 

that are used for noise certification must be 
listed in the approved Rotorcraft Flight 
Manual. 

(f) 

Approach reference profile. 

(1) Figure H3 

illustrates approach profile, including ref-
erence conditions. 

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