913
Federal Aviation Administration, DOT
§ 36.9
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—
(i) The airplane may not be a Stage 1
airplane after the change in type de-
sign; 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.
(e)
Stage 3 airplanes. If an airplane is
a Stage 3 airplane prior to the change
in type design, the following apply, in
addition to the provisions of paragraph
(b) of this section:
(1) If compliance with Stage 3 noise
levels is not required before the change
in type design, the airplane must—
(i) Be a Stage 2 airplane after the
change in type design and compliance
must be shown under the provisions of
paragraph (d)(1) or (d)(2) of this sec-
tion, as appropriate; or
(ii) Remain a Stage 3 airplane after
the change in type design. Compliance
must be shown under the provisions of
paragraph (e)(2) of this section.
(2) If compliance with Stage 3 noise
levels is required before the change in
type design, the airplane must be a
Stage 3 airplane after the change in
type design.
(3) Applications on or after [August
14, 1989.] The airplane must remain a
Stage 3 airplane after the change in
type design.
(4) If an airplane is a Stage 3 airplane
prior to a change in type design, and
becomes a Stage 4 after the change in
type design, the airplane must remain
a Stage 4 airplane.
(f)
Stage 4 airplanes. If an airplane is
a Stage 4 airplane prior to a change in
type design, the airplane must remain
a Stage 4 airplane after the change in
type design.
[Amdt. 36–7, 42 FR 12371, Mar. 3, 1977; Amdt.
36–8, 43 FR 8730, Mar. 2, 1978; Amdt. 36–10, 43
FR 28420, June 29, 1978; Amdt. 36–12, 46 FR
33464, June 29, 1981; Amdt. 36–15, 53 FR 16366,
May 6, 1988; 53 FR 18950, May 25, 1988; Amdt.
36–17, 54 FR 21042, May 15, 1989; Amdt. 36–54,
67 FR 45212, July 8, 2002; Amdt. 36–26, 70 FR
38749, July 5, 2005]
§ 36.9
Acoustical change: Propeller-
driven small airplanes and pro-
peller-driven commuter category
airplanes.
For propeller-driven small airplanes
in the primary, normal, utility, acro-
batic, transport, and restricted cat-
egories and for propeller-driven, com-
muter category airplanes for which an
acoustical change approval is applied
for under § 21.93(b) of this chapter after
January 1, 1975, the following apply:
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