769
Federal Aviation Administration, DOT
§ 36.7
Method for Free-Field Calibration of
Laboratory Standard Microphones by
the Reciprocity Technique, edition 1.0,
1995 (IEC 61094–3) IBR approved for ap-
pendix A to part 36.
(6) Publication No. 61094–4, Measure-
ment Microphones—Part 4: Specifica-
tions for Working Standard Micro-
phones, edition 1.0, 1995, (IEC 61094–4)
IBR approved for appendix A to part 36.
(7) Publication No. 61260,
Electroacoustics-Octave-Band and
Fractional-Octave-Band Filters, edi-
tion 1.0, 1995, (IEC 61260), IBR approved
for appendix A to part 36.
(8) Publication No, 60942,
Electroacoustics-Sound Calibrators,
edition 2.0, 1997, (IEC 60942) IBR ap-
proved for appendix A to part 36.
(d) Society of Automotive Engineers,
Inc. (SAE), 400 Commonwealth Drive,
Warrentown, PA 15096,
http://
www.sae.org/pubs/.
(1) ARP 866A, Standard Values at At-
mospheric Absorption as a Function of
Temperature and Humidity for use in
Evaluating Aircraft Flyover Noise,
March 15, 1975, IBR approved for appen-
dix H to part 36.
(2) [Reserved]
[Doc. No. FAA–2015–3782, Amdt. No. 36–31, 82
FR 46129, Oct. 4, 2017]
§ 36.7
Acoustical change: Transport
category large airplanes and jet air-
planes.
(a)
Applicability.
This section applies
to all transport category large air-
planes and jet airplanes for which an
acoustical change approval is applied
for under § 21.93(b) of this chapter.
(b)
General requirements.
Except as
otherwise specifically provided, for
each airplane covered by this section,
the acoustical change approval require-
ments are as follows:
(1) In showing compliance, noise lev-
els must be measured and evaluated in
accordance with the applicable proce-
dures and conditions prescribed in Ap-
pendix A of this part.
(2) Compliance with the noise limits
prescribed in section B36.5 of appendix
B must be shown in accordance with
the applicable provisions of sections
B36.7 and B36.8 of appendix B of this
part.
(c)
Stage 1 airplanes.
For each Stage 1
airplane prior to the change in type de-
sign, in addition to the provisions of
paragraph (b) of this section, the fol-
lowing apply:
(1) If an airplane is a Stage 1 airplane
prior to the change in type design, it
may not, after the change in type de-
sign, exceed the noise levels created
prior to the change in type design. The
tradeoff provisions of section B36.6 of
appendix B of this part may not be
used to increase the Stage 1 noise lev-
els, unless the aircraft qualifies as a
Stage 2 airplane.
(2) In addition, for an airplane for
which application is made after Sep-
tember 17, 1971—
(i) There may be no reduction in
power or thrust below the highest air-
worthiness approved power or thrust,
during the tests conducted before and
after the change in type design; and
(ii) During the flyover and lateral
noise tests conducted before the change
in type design, the quietest airworthi-
ness approved configuration available
for the highest approved takeoff weight
must be used.
(d)
Stage 2 airplanes.
If an airplane is
a Stage 2 airplane prior to the change
in type design, the following apply, in
addition to the provisions of paragraph
(b) of this section:
(1)
Airplanes with high bypass ratio jet
engines.
For an airplane that has jet
engines with a bypass ratio of 2 or
more before a change in type design—
(i) The airplane, after the change in
type design, may not exceed either (A)
each Stage 3 noise limit by more than
3 EPNdB, or (B) each Stage 2 noise
limit, whichever is lower:
(ii) The tradeoff provisions of section
B36.6 of appendix B of this part may be
used in determining compliance under
this paragraph with respect to the
Stage 2 noise limit or to the Stage 3
plus 3 EPNdB noise limits, as applica-
ble; and
(iii) During the flyover and lateral
noise test conducted before the change
in type design, the quietest airworthi-
ness approved configuration available
for the highest approved takeoff weight
must be used.
(2)
Airplanes that do not have high by-
pass ratio jet engines.
For an airplane
that does not have jet engines with a
bypass ratio of 2 or more before a
change in type design—
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