Code of Federal Regulations - Title 14

977

Federal Aviation Administration, DOT

Pt. 36, App. J

(b)

Data reporting. After the completion of

the test the following data must be included
in the test report furnished to the FAA:

(1) Measured and corrected sound levels ob-

tained with equipment conforming to the
standards prescribed in section J36.109 of this
appendix;

(2) The type of equipment used for meas-

urement and analysis of all acoustic, aircraft
performance and flight path, and meteoro-
logical data;

(3) The atmospheric environmental data

required to demonstrate compliance with
this appendix, measured throughout the test
period;

(4) Conditions of local topography, ground

cover, or events which may interfere with
the sound recording;

(5) The following helicopter information:
(i) Type, model, and serial numbers, if any,

of helicopter, engine(s) and rotor(s);

(ii) Gross dimensions of helicopter, loca-

tion of engines, rotors, type of antitorque
system, number of blades for each rotor, and
reference operating conditions for each en-
gine and rotor;

(iii) Any modifications of non-standard

equipment likely to affect the noise charac-
teristics of the helicopter;

(iv) Maximum takeoff weight for which

certification under this appendix is re-
quested;

(v) Aircraft configuration, including land-

ing gear positions;

(vi) V

or V

(whichever is less) and the

adjusted reference airspeed;

(vii) Aircraft gross weight for each test

run;

(viii) Indicated and true airspeed for each

test run;

(ix) Ground speed, if measured, for each

run;

(x) Helicopter engine performance as deter-

mined from aircraft instruments and manu-
facturer’s data; and

(xi) Aircraft flight path above ground

level, referenced to the elevation of the noise
measurement station, in feet, determined by
an FAA-approved method which is inde-
pendent of normal flight instrumentation,
such as radar tracking, theodolite triangula-
tion, laser trajectography, or photoscaling
techniques; and

(6) Helicopter position and performance

data required to make the adjustments pre-
scribed under section J36.205 of this appendix
and to demonstrate compliance with the per-
formance and position restrictions pre-
scribed under section J36.105 of this appendix
must be recorded at an FAA-approved sam-
pling rate.

Section J36.113 [Reserved]

ART

C—N

OISE

VALUATION AND

ALCULATIONS

NDER

§ 36.803

Section J36.201 Noise Evaluation in SEL.

The noise evaluation measure shall be the

sound exposure level (SEL) in units of dB(A)
as prescribed under section J36.109(b) of this
appendix. The SEL value for each flyover
may be directly determined by use of an in-
tegrating sound level meter. Specifications
for the integrating sound level meter and re-
quirements governing the use of such instru-
mentation are prescribed under section
J36.109 of this appendix.

Section J36.203 Calculation of Noise Levels.

(a) To demonstrate compliance with the

noise level limits specified under section
J36.305 of this appendix, the SEL noise levels
from each valid flyover, corrected as nec-
essary to reference conditions under section
J36.205 of this appendix, must be
arithmetically averaged to obtain a single
SEL dB(A) mean value for the flyover series.
No individual flyover run may be omitted
from the averaging process, unless otherwise
specified or approved by the FAA.

(b) The minimum sample size acceptable

for the helicopter flyover certification meas-
urements is six. The number of samples must
be large enough to establish statistically a 90
percent confidence limit that does not ex-
ceed

1.5 dB(A).

formed under this section, including the cal-
culated 90 percent confidence limits, must be
documented and provided under the report-
ing requirements of section J36.111 of this
appendix.

Section J36.205 Detailed Data Correction

Procedures.

(a) When certification test conditions

measured under part B of this appendix differ
from the reference test conditions prescribed
under section J36.3 of this appendix, appro-
priate adjustments shall be made to the
measured noise data in accordance with the
methods set out in paragraphs (b) and (c) of
this section. At minimum, appropriate ad-
justments shall be made for off-reference al-
titude and for the difference between ref-
erence airspeed and adjusted reference air-
speed.

(b) The adjustment for off-reference alti-

tude may be approximated from:

<delta>J

=12.5 log

/492) dB;

where <delta>J

is the quantity in decibels

that must be algebraically added to the
measured SEL noise level to correct for an
off-reference flight path, H

is the height, in

feet, of the test helicopter when directly
over the noise measurement point, and the
constant (12.5) accounts for the effects on

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