**
Appendix B to Part 36 - Noise Levels for Transport
Category and Jet Airplanes Under §36.103**
Sec.

B36.1 *Noise Measurement and Evaluation.*

B36.2 *Noise Evaluation Metric.*

B36.3 *Reference Noise Measurement Points.*

B36.4 *Test Noise Measurement Points.*

B36.5 *Maximum Noise Levels.*

B36.6 *Trade-Offs.*

B36.7 *Noise Certification Reference Procedures and Conditions.*

B36.8 *Noise Certification Test Procedures.*

**Section B36.1 Noise Measurement and Evaluation**

Compliance with this appendix must be shown with noise levels measured
and evaluated using the procedures of appendix A of this part, or under
approved equivalent procedures.

**Section B36.2 Noise Evaluation Metric**

The noise evaluation metric is the effective perceived noise level
expressed in EPNdB, as calculated using the procedures of appendix A of
this part.

**Section B36.3 Reference Noise Measurement Points**

When tested using the procedures of this part, except as provided in
section B36.6, an airplane may not exceed the noise levels specified in
section B36.5 at the following points on level terrain:

(a) Lateral full-power reference noise measurement point:

(1) For jet airplanes: The point on a line parallel to and 1,476 feet
(450 m) from the runway centerline, or extended centerline, where the
noise level after lift-off is at a maximum during takeoff. For the purpose
of showing compliance with Stage 1 or Stage 2 noise limits for an airplane
powered by more than three jet engines, the distance from the runway
centerline must be 0.35 nautical miles (648 m). For jet airplanes, when
approved by the FAA, the maximum lateral noise at takeoff thrust may be
assumed to occur at the point (or its approved equivalent) along the
extended centerline of the runway where the airplane reaches 985 feet (300
meters) altitude above ground level. A height of 1427 feet (435 meters)
may be assumed for Stage 1 or Stage 2 four engine airplanes. The altitude
of the airplane as it passes the noise measurement points must be within
+328 to −164 feet (+100 to −50 meters) of the target altitude. For
airplanes powered by other than jet engines, the altitude for maximum
lateral noise must be determined experimentally.

(2) For propeller-driven airplanes: The point on the extended
centerline of the runway above which the airplane, at full takeoff power,
reaches a height of 2,133 feet (650 meters). For tests conducted before
[the effective date of this final rule], an applicant may use the
measurement point specified in section B36.3(a)(1) as an alternative.

(b) Flyover reference noise measurement point: The point on the
extended centerline of the runway that is 21,325 feet (6,500 m) from the
start of the takeoff roll;

(c) Approach reference noise measurement point: The point on the
extended centerline of the runway that is 6,562 feet (2,000 m) from the
runway threshold. On level ground, this corresponds to a position that is
394 feet (120 m) vertically below the 3° descent path, which originates at
a point on the runway 984 feet (300 m) beyond the threshold.

**Section B36.4 Test noise measurement points.**

(a) If the test noise measurement points are not located at the
reference noise measurement points, any corrections for the difference in
position are to be made using the same adjustment procedures as for the
differences between test and reference flight paths.

(b) The applicant must use a sufficient number of lateral test noise
measurement points to demonstrate to the FAA that the maximum noise level
on the appropriate lateral line has been determined. For jet airplanes,
simultaneous measurements must be made at one test noise measurement point
at its symmetrical point on the other side of the runway. Propeller-driven
airplanes have an inherent asymmetry in lateral noise. Therefore,
simultaneous measurements must be made at each and every test noise
measurement point at its symmetrical position on the opposite side of the
runway. The measurement points are considered to be symmetrical if they
are longitudinally within 33 feet (±10 meters) of each other.

**Section B36.5 Maximum Noise Levels**

Except as provided in section B36.6 of this appendix, maximum noise
levels, when determined in accordance with the noise evaluation methods of
appendix A of this part, may not exceed the following:

(a) For acoustical changes to Stage 1 airplanes, regardless of the
number of engines, the noise levels prescribed under
§36.7(c) of this part.

(b) For any Stage 2 airplane regardless of the number of engines:

(1) Flyover: 108 EPNdB for maximum weight of 600,000 pounds or more;
for each halving of maximum weight (from 600,000 pounds), reduce the limit
by 5 EPNdB; the limit is 93 EPNdB for a maximum weight of 75,000 pounds or
less.

(2) Lateral and approach: 108 EPNdB for maximum weight of 600,000
pounds or more; for each halving of maximum weight (from 600,000 pounds),
reduce the limit by 2 EPNdB; the limit is 102 EPNdB for a maximum weight
of 75,000 pounds or less.

(c) For any Stage 3 airplane:

(1) Flyover.

(i) For airplanes with more than 3 engines: 106 EPNdB for maximum
weight of 850,000 pounds or more; for each halving of maximum weight (from
850,000 pounds), reduce the limit by 4 EPNdB; the limit is 89 EPNdB for a
maximum weight of 44,673 pounds or less;

(ii) For airplanes with 3 engines: 104 EPNdB for maximum weight of
850,000 pounds or more; for each halving of maximum weight (from 850,000
pounds), reduce the limit by 4 EPNdB; the limit is 89 EPNdB for a maximum
weight of 63,177 pounds or less; and

(iii) For airplanes with fewer than 3 engines: 101 EPNdB for maximum
weight of 850,000 pounds or more; for each halving of maximum weight (from
850,000 pounds), reduce the limit by 4 EPNdB; the limit is 89 EPNdB for a
maximum weight of 106,250 pounds or less.

(2) Lateral, regardless of the number of engines: 103 EPNdB for maximum
weight of 882,000 pounds or more; for each halving of maximum weight (from
882,000 pounds), reduce the limit by 2.56 EPNdB; the limit is 94 EPNdB for
a maximum weight of 77,200 pounds or less.

(3) Approach, regardless of the number of engines: 105 EPNdB for
maximum weight of 617,300 pounds or more; for each halving of maximum
weight (from 617,300 pounds), reduce the limit by 2.33 EPNdB; the limit is
98 EPNdB for a maximum weight of 77,200 pounds or less.

**Section B36.6 Trade-Offs**

Except when prohibited by sections 36.7(c)(1) and 36.7(d)(1)(ii), if
the maximum noise levels are exceeded at any one or two measurement
points, the following conditions must be met:

(a) The sum of the exceedance(s) may not be greater than 3 EPNdB;

(b) Any exceedance at any single point may not be greater than 2 EPNdB,
and

(c) Any exceedance(s) must be offset by a corresponding amount at
another point or points.

**Section B36.7 Noise Certification Reference Procedures and
Conditions**

(a) General conditions:

(1) All reference procedures must meet the requirements of section 36.3
of this part.

(2) Calculations of airplane performance and flight path must be made
using the reference procedures and must be approved by the FAA.

(3) Applicants must use the takeoff and approach reference procedures
prescribed in paragraphs (b) and (c) of this section.

(4) [Reserved]

(5) The reference procedures must be determined for the following
reference conditions. The reference atmosphere is homogeneous in terms of
temperature and relative humidity when used for the calculation of
atmospheric absorption coefficients.

(i) Sea level atmospheric pressure of 2116 pounds per square foot (psf)
(1013.25 hPa);

(ii) Ambient sea-level air temperature of 77 °F (25 °C, i.e. ISA+10
°C);

(iii) Relative humidity of 70 per cent;

(iv) Zero wind.

(v) In defining the reference takeoff flight path(s) for the takeoff
and lateral noise measurements, the runway gradient is zero.

(b) Takeoff reference procedure:

The takeoff reference flight path is to be calculated using the
following:

(1) Average engine takeoff thrust or power must be used from the start
of takeoff to the point where at least the following height above runway
level is reached. The takeoff thrust/power used must be the maximum
available for normal operations given in the performance section of the
airplane flight manual under the reference atmospheric conditions given in
section B36.7(a)(5).

(i) For Stage 1 airplanes and for Stage 2 airplanes that do not have
jet engines with a bypass ratio of 2 or more, the following apply:

(A): For airplanes with more than three jet engines -- 700 feet (214
meters).

(B): For all other airplanes -- 1,000 feet (305 meters).

(ii) For Stage 2 airplanes that have jet engines with a bypass ratio of
2 or more and for Stage 3 airplanes, the following apply:

(A): For airplanes with more than three engines -- 689 feet (210
meters).

(B): For airplanes with three engines -- 853 feet (260 meters).

(C): For airplanes with fewer than three engines -- 984 feet (300
meters).

(2) Upon reaching the height specified in paragraph (b)(1) of this
section, airplane thrust or power must not be reduced below that required
to maintain either of the following, whichever is greater:

(i) A climb gradient of 4 per cent; or

(ii) In the case of multi-engine airplanes, level flight with one
engine inoperative.

(3) For the purpose of determining the lateral noise level, the
reference flight path must be calculated using full takeoff power
throughout the test run without a reduction in thrust or power. For tests
conducted before [the effective date of this final rule], a single
reference flight path that includes thrust cutback in accordance with
paragraph (b)(2) of this section, is an acceptable alternative in
determining the lateral noise level.

(4) The takeoff reference speed is the all-engine operating takeoff
climb speed selected by the applicant for use in normal operation; this
speed must be at least V2+10kt (V2+19km/h) but may not be greater than
V2+20kt (V2+37km/h). This speed must be attained as soon as practicable
after lift-off and be maintained throughout the takeoff noise
certification test. For Concorde airplanes, the test day speeds and the
acoustic day reference speed are the minimum approved value of V2+35
knots, or the all-engines-operating speed at 35 feet, whichever speed is
greater as determined under the regulations constituting the type
certification basis of the airplane; this reference speed may not exceed
250 knots. For all airplanes, noise values measured at the test day speeds
must be corrected to the acoustic day reference speed.

(5) The takeoff configuration selected by the applicant must be
maintained constantly throughout the takeoff reference procedure, except
that the landing gear may be retracted. Configuration means the center of
gravity position, and the status of the airplane systems that can affect
airplane performance or noise. Examples include, the position of lift
augmentation devices, whether the APU is operating, and whether air bleeds
and engine power take-offs are operating;

(6) The weight of the airplane at the brake release must be the maximum
takeoff weight at which the noise certification is requested, which may
result in an operating limitation as specified in §36.1581(d); and

(7) The average engine is defined as the average of all the
certification compliant engines used during the airplane flight tests, up
to and during certification, when operating within the limitations and
according to the procedures given in the Flight Manual. This will
determine the relationship of thrust/power to control parameters (e.g., N1
or EPR). Noise measurements made during certification tests must be
corrected using this relationship.

(c) Approach reference procedure:

The approach reference flight path must be calculated using the
following:

(1) The airplane is stabilized and following a 3° glide path;

(2) For subsonic airplanes, a steady approach speed of Vref
+ 10 kts (Vref + 19 km/h) with thrust and power stabilized
must be established and maintained over the approach measuring point. Vref
is the reference landing speed, which is defined as the speed of the
airplane, in a specified landing configuration, at the point where it
descends through the landing screen height in the determination of the
landing distance for manual landings. For Concorde airplanes, a steady
approach speed that is either the landing reference speed + 10 knots or
the speed used in establishing the approved landing distance under the
airworthiness regulations constituting the type certification basis of the
airplane, whichever speed is greater. This speed must be established and
maintained over the approach measuring point.

(3) The constant approach configuration used in the airworthiness
certification tests, but with the landing gear down, must be maintained
throughout the approach reference procedure;

(4) The weight of the airplane at touchdown must be the maximum landing
weight permitted in the approach configuration defined in paragraph (c)(3)
of this section at which noise certification is requested, except as
provided in §36.1581(d) of this part; and

(5) The most critical configuration must be used; this configuration is
defined as that which produces the highest noise level with normal
deployment of aerodynamic control surfaces including lift and drag
producing devices, at the weight at which certification is requested. This
configuration includes all those items listed in section A36.5.2.5 of
appendix A of this part that contribute to the noisiest continuous state
at the maximum landing weight in normal operation.

**Section B36.8 Noise Certification Test Procedures**

(a) All test procedures must be approved by the FAA.

(b) The test procedures and noise measurements must be conducted and
processed in an approved manner to yield the noise evaluation metric EPNL,
in units of EPNdB, as described in appendix A of this part.

(c) Acoustic data must be adjusted to the reference conditions
specified in this appendix using the methods described in appendix A of
this part. Adjustments for speed and thrust must be made as described in
section A36.9 of this part.

(d) If the airplane's weight during the test is different from the
weight at which noise certification is requested, the required EPNL
adjustment may not exceed 2 EPNdB for each takeoff and 1 EPNdB for each
approach. Data approved by the FAA must be used to determine the variation
of EPNL with weight for both takeoff and approach test conditions. The
necessary EPNL adjustment for variations in approach flight path from the
reference flight path must not exceed 2 EPNdB.

(e) For approach, a steady glide path angle of 3° ± 0.5° is acceptable.

(f) If equivalent test procedures different from the reference
procedures are used, the test procedures and all methods for adjusting the
results to the reference procedures must be approved by the FAA. The
adjustments may not exceed 16 EPNdB on takeoff and 8 EPNdB on approach. If
the adjustment is more than 8 EPNdB on takeoff, or more than 4 EPNdB on
approach, the resulting numbers must be more than 2 EPNdB below the limit
noise levels specified in section B36.5.

(g) During takeoff, lateral, and approach tests, the airplane variation
in instantaneous indicated airspeed must be maintained within ±3% of the
average airspeed between the 10 dB-down points. This airspeed is
determined by the pilot's airspeed indicator. However, if the
instantaneous indicated airspeed exceeds ±3 kt (±5.5 km/h) of the average
airspeed over the 10 dB-down points, and is determined by the FAA
representative on the flight deck to be due to atmospheric turbulence,
then the flight so affected must be rejected for noise certification
purposes.

**Note:** Guidance material on the use of equivalent procedures is
provided in the current advisory circular for this part.

[Amdt. 36-54, 67 FR 45235, July 8, 2002; Amdt. 36-24, 67 FR
63196, Oct. 10, 2002]