836
14 CFR Ch. I (1–1–19 Edition)
Pt. 36, App. J
<delta>J
1
= 12.5 log
10
(H
T
/492) dB;
where <delta>J
1
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
T
is the
height, in feet, of the test helicopter
when directly over the noise measure-
ment point, and the constant (12.5) ac-
counts for the effects on spherical
spreading and duration from the off-ref-
erence altitude.
(c) The adjustment for the difference be-
tween reference airspeed and adjusted ref-
erence airspeed is calculated from:
<delta>J
3
= 10 log
10
(V
RA
/V
R
) dB;
Where <delta>J
3
is the quantity in decibels
that must be algebraically added to the
measured SEL noise level to correct for
the influence of the adjustment of the
reference airspeed on the duration of the
measured flyover event as perceived at
the noise measurement station, V
R
is the
reference airspeed as prescribed under
section J36.3.(c) of this appendix, and V
RA
is the adjusted reference airspeed as pre-
scribed under section J36.105(c) of this
appendix.
(d) No correction for source noise during
the flyover other than the variation of
source noise accounted for by the adjust-
ment of the reference airspeed prescribed for
under section J36.105(c) of this appendix need
be applied.
(e) No correction for the difference be-
tween the reference ground speed and the ac-
tual ground speed need be applied.
(f) No correction for off-reference atmos-
pheric attenuation need be applied.
(g) The SEL adjustments must be less than
2.0 dB(A) for differences between test and ref-
erence flight procedures prescribed under
section J36.105 of this appendix unless a larg-
er adjustment value is approved by the FAA.
(h) All data used and calculations per-
formed under this section must be docu-
mented and provided under the reporting re-
quirements specified under section J36.111 of
this appendix.
P
ART
D—N
OISE
L
IMITS
P
ROCEDURE
U
NDER
§ 36.805
Section J36.301 Noise Measurement, Evaluation,
and Calculation.
Compliance with this part of this appendix
must be shown with noise levels measured,
evaluated, and calculated as prescribed
under parts B and C of this appendix.
Section J36.303 [Reserved]
Section J36.305 Noise Limits.
For compliance with this appendix, the
calculated noise levels of the helicopter, at
the measuring point described in section
J36.101 of this appendix, must be shown to
not exceed the following (with appropriate
interpolation between weights):
(a) For primary, normal, transport, and re-
stricted category helicopters having a max-
imum certificated takeoff weight of not
more than 7,000 pounds that are noise tested
under this appendix:
(1) Stage 2 noise limit is constant at 82
decibels SEL for helicopters up to 1,737
pounds (787 kg) maximum certificated take-
off weight (mass) and increases linearly with
the logarithm of the helicopter weight at a
rate of 3.0 decibels SEL per the doubling of
weight thereafter. The limit may be cal-
culated by the equation:
L
AE
(limit) = 82 + 3.0 [log
10
(MTOW/1737)/
log
10
(2)] dB,
where MTOW is the maximum takeoff
weight, in pounds, for which certification
under this appendix is requested.
(2) Stage 3 noise limit is constant at 82
decibels SEL for helicopters up to 3,125
pounds (1,417 kg) maximum certificated
takeoff weight (mass) and increases linearly
with the logarithm of the helicopter weight
at a rate of 3.0 decibels SEL per the doubling
of weight thereafter. The limit may be cal-
culated using the equation:
L
AE
(limit) = 82 + 3.0 [log10(MTOW/3125)/
log10(2)] dB,
where MTOW is the maximum takeoff
weight, in pounds.
(b) The procedures required in this amend-
ment shall be done in accordance with the
International Electrotechnical Commission
IEC Publication No. 804, entitled ‘‘Inte-
grating-averaging Sound Level Meters,’’
First Edition, dated 1985. This incorporation
by reference was approved by the Director of
the Federal Register in accordance with 5
U.S.C. 552(a) and 1 CFR part 51. Copies may
be obtained from the Bureau Central de la
Commission Electrotechnique Inter-
nationale, 1, rue de Varembe, Geneva, Swit-
zerland or the American National Standard
Institute, 1430 Broadway, New York City,
New York 10018, or at the National Archives
and Records Administration (NARA). For in-
formation on the availability of this mate-
rial at NARA, call 202–741–6030, or go to:
http://www.archives.gov/federal
l
register/
code
l
of
l
federal
l
regulations/
ibr
l
locations.html.
[Doc. No. 26910, 57 FR 42855, Sept. 16, 1992, as
amended by Amdt. 36–20, 57 FR 46243, Oct. 7,
1992; 69 FR 18803, Apr. 9, 2004; Amdt. 36–25, 69
FR 31234, June 2, 2004; Amdt. 36–30, 79 FR
12045, Mar. 4, 2014; FAA Doc. No. FAA–2015–
3782, Amdt. No. 36–31, 82 FR 46131, Oct. 4,
2017]
VerDate Sep<11>2014
12:50 Apr 30, 2019
Jkt 247046
PO 00000
Frm 00846
Fmt 8010
Sfmt 8002
Y:\SGML\247046.XXX
247046
spaschal on DSK3GDR082PROD with CFR