a. Explanation
This section specifies the methodology of the integrated method used for adjusting measured noise data to reference conditions
b. Supplemental Information
(1) Section 6.6 of the Appended ICAO TM provides details of an approved integrated adjustment method when the airplane is operated at stabilized flight path and thrust (power) conditions during the noise measurement period.
c. Procedures
None
261. Section A36.9.4.2 PNLT computations.
(a) The portions of the test flight path and the reference flight path described in paragraph
(a)(1) and (2), and illustrated in Figure A36-10, include the noise time history that is relevant to the calculation of flyover and approach EPNL. In figure A36-10:
Figure A36-10: Correspondence between measured and reference flight paths for the application of the integrated methods of adjustment
(1) XY represents the portion of the measured flight path that includes the noise time history relevant to the calculation of flyover and approach EPNL; XrYr represents the corresponding reference flight path.
(2) The points Q0, Q1, Qn represent airplane positions on the measured flight path at time t0, t1 and tn respectively. Point Q1 is the point at which the noise was emitted and observed as one-third octave values SPL(i)1 at the noise measuring station K at time t1. Point Qr1 represents the corresponding position on the reference flight path for noise observed as SPL(i)r1 at the reference measuring station Kr at time tr1. Q1K and Qr1Kr are respectively the measured and reference noise propagation paths, which in each case form the angle q1 with their respective flight paths . Qr0 and Qrn are similarly the points on the reference flight path corresponding to Q0 and Qn on the measured flight path . Q0 and Qn are chosen so that between Qr0 and Qrn all values of PNLTr (computed as described in paragraphs A36.9.4.2.2 and A36.9.4.2.3) within 10 dB of the peak value are included.
(b) The portions of the test flight path and the reference flight path described in paragraph
(b)(1) and (2), and illustrated in Figure A36-11(a) and (b), include the noise time history that is relevant to the calculation of lateral EPNL.
(1) In figure A36-11(a) XY represents the portion of the measured flight path that includes the noise time history that is relevant to the calculation of lateral EPNL; in figure A36-11(b), XrYr represents the corresponding portion of the reference flight path .
(2) The points Q0, Q1 and Qn represent airplane positions on the measured flight path at time t0, t1 and tn respectively. Point Q1 is the point at which the noise was emitted and observed as onethird octave values SPL(i)1 at the noise measuring station K at time t1. The point Qr1 represents the corresponding position on the reference flight path for noise observed as SPL(i)r1 at the measuring station Kr at time tr1. Q1K and Qr1Kr are respectively the measured and reference noise propagation paths. Qr0 and Qrn are similarly the points on the reference flight path corresponding to Q0 and Qn on the measured flight path . Q0 and Qn are chosen so that between Qro and Qrn all values of PNLTr (computed as described in paragraphs A36.9.4.2.2 and A36.9.4.2.3) within 10 dB of the peak value are included. In this case Kr is only specified as being on a particular lateral line. The position of Kr and Qr1 are determined from the following requirements:
(i) Q1K and Qr1Kr form the same angle q1 with their respective flight paths ; and
(ii) The differences between the angles y1 and yr1 must be minimized using a method, approved by the FAA. The differences between the angles are minimized since, for geometrical reasons, it is generally not possible to choose Kr so that the condition described in paragraph A36.9.4.2(b)(2)(i) is met while at the same time keeping y1 and yr1 equal.
Note 1: For the lateral noise measurement, sound propagation is affected not only by inverse square and atmospheric attenuation, but also by ground absorption and reflection effects which depend mainly on the angle y.
O MEASURED FIGHT PATH
PROJECTION OF FLIGHT
PATH ON GROUND PLANE An
RUNWAY CENTRE LINE Figure A36-11(a): Measured Flight Path — Y, On REFERENCE FLIGHT PATH X,• Oro
RUNWAY CENTRE LINE
PARALLEL TO THE RUNWAY CENTRE
LINE AT SPECIFIED DISTANCE Figure A36-11(b): Reference Flight Path Page 156
a. Explanation
This section specifies the portions of the test and reference flight paths that are significant for computation of EPNLr (i.e., encompassing the 10 dB-down points), the symbols for airplane positions at different time intervals, and noise angles (which are equated between respective test and reference flight paths).
b. Supplemental Information
(1) Emission Angles: For the integrated method, each one-half second noise data record will define a separate noise emission angle. This angle will then define the location of each data record along the reference flight path. The distance between consecutive data records along the reference flight path divided by the reference path speed provides the time interval between reference data records. The reference duration of each of these data records can be determined by obtaining the average of the two intervals between the adjacent data records. (This may be different than 0.5 seconds). See section 6.6 of the Appended ICAO TM for discussion of time interval computations using the integrated method.
c. Procedures
(1) Elevation Angles: If the integrated method is used for lateral noise measurements and it is not possible to equate the elevation angle for the test flight path to that for the reference flight path after equating test and reference noise emission angles, then the elevation angle differences should be minimized using a method approved by the FAA.
262. Section A36.9.4.2.1
In paragraphs A36.9.4.2(a)(2) and (b)(2) the time tr1 is later (for Qr1Kr > Q1K) than t1 by two separate amounts:
(1) The time taken for the airplane to travel the distance Qr1Qr0 at a speed Vr less the time taken for it to travel Q1Q0 at V;
(2) The time taken for sound to travel the distance Qr1Kr - Q1K.
Note: For the flight paths described in paragraphs A36.9.4.2(a) and (b), the use of thrust or power cut-back will result in test and reference flight paths at full thrust or power and at cut-back thrust or power. Where the transient region between these thrust or power levels affects the final result, an interpolation must be made between them by an approved method such as that given in the current advisory circular for this part.
a. Explanation
This section specifies the factors that relate to the difference in the emission times between the reference flight path and the test flight path using the integrated method.
b. Supplementary Information
(1) See section 6.6 of the Appended ICAO TM for discussion of time interval computations using the integrated method.
c. Procedures
None
263. Section A36.9.4.2.2
The measured values of SPL(i)1 must be adjusted to the reference values SPL(i)r1 to account for the differences between measured and reference noise path lengths and between measured and reference atmospheric conditions, using the methods of section A36.9.3.2.1 of this appendix. A corresponding value of PNLr1 must be computed according to the method in section A36.4.2. Values of PNLr must be computed for times t0 through tn.
264. Section A36.9.4.2.3
For each value of PNLr1, a tone correction factor C1 must be determined by analyzing the reference values SPL(i)r using the methods of section A36.4.3 of this appendix, and added to PNLr1 to yield PNLTr1. Using the process described in this paragraph, values of PNLTr must be computed for times t0 through tn.
265. Section A36.9.4.3 Duration correction.
266. Section A36.9.4.3.1
The values of PNLTr corresponding to those of PNLT at each one-half second interval must be plotted against time (PNLTr1 at time tr1). The duration correction must then be determined using the method of section A36.4.5.1 of this appendix, to yield EPNLr.
a. Explanation
This section specifies the method of determining the duration correction needed to obtain EPNLr when using the “integrated” method.
b. Supplementary Information
(1) See section 6.6.7 of the appended ICAO TM for discussion of adjusted EPNL computations when using the “integrated” method.
c. Procedures
(1) Application of Band Sharing Adjustment for “Integrated” Method: See the Supplementary Information and Procedures presented in A36.4.4.2. This adjustment must be applied to the maximum PNLTr before calculation of the Duration Correction and EPNLr.
(2) Application of High-Altitude Site Jet Noise Adjustment for “Integrated” Method: When the Equivalent Procedure for use of high-altitude test sites (Elevation > 1200 feet MSL) is employed, and the “Integrated” adjustment method is used to determine EPNLr values, the adjustments must be applied either to the measured one-third octave band sound pressure levels, SPL(i,k), or to the adjusted one-third-octave-band sound pressure levels, SPL(i,k)r, throughout the entire 10 dB-down period. See Appendix 6 of the appended ICAO TM, for information on the equivalent procedure for testing at high-altitude sites.
267. Section A36.9.4.4 Source noise adjustment.
268. Section A36.9.4.4.1
A source noise adjustment, D3, must be determined using the methods of section A36.9.3.4 of this appendix.
269. Section A36.9.5 Flight Path Identification Positions.
Position Description
A Start of Takeoff roll B Lift-off C Start of first constant climb D Start of thrust reduction E Start of second constant climb F End of noise certification Takeoff flight path G Start of noise certification Approach flight path H Position on Approach path directly above noise measuring station I Start of level-off J Touchdown K Noise measurement point Kr Reference measurement point K1 Flyover noise measurement point K2 Lateral noise measurement point K3 Approach noise measurement point M End of noise certification Takeoff flight track O Threshold of Approach end of runway P Start of noise certification Approach flight track Q Position on measured Takeoff flight path corresponding to apparent PNLTM at station K See section A36.9.3.2 Qr Position on corrected Takeoff flight path corresponding to PNLTM at station K. See section A36.9.3.2 V airplane test speed Vr airplane reference speed
270. Section A36.9.6 Flight Path Distances.
Distanc e Unit Meaning
AB feet (meters) Length of takeoff roll. The distance along the runway between the start of takeoff roll and lift off.
AK feet (meters) Takeoff measurement distance. The distance from the start of roll to the takeoff noise measurement station along the extended center line of the runway.
AM feet (meters) Takeoff flight track distance. The distance from the start of roll to the takeoff flight track position along the extended center line of the runway after which the position of the airplane need no longer be recorded.
QK feet (meters) Measured noise path. The distance from the measured airplane position Q to station K.
QrKr feet (meters) Reference noise path. The distance from the reference airplane position Qr to station Kr.
K3H feet (meters) Airplane approach height. The height of the airplane above the approach measuring station.
OK3 feet (meters) Approach measurement distance. The distance from the runway threshold to the approach measurement station along the extended center line of the runway.
OP feet (meters) Approach flight track distance. The distance from the runway threshold to the approach flight track position along the extended center line of the runway after which the position of the airplane need no longer be recorded.
a. Explanation
This section specifies the flight path identification positions, their symbols, and associated units.
b. Supplemental Information
None
c. Procedures
None
271. - 289--RESERVED
290. 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.
a. Explanation
Appendix B addresses the noise measurement and evaluation requirements, test and reference procedures, and maximum noise levels (noise limits) that FAA uses as the basis for assessment of compliance of subsonic transport category large airplanes and jet airplanes with part 36.
b. Supplemental Information
None
c. Procedures
None
291. 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.
a. Explanation
This section specifies that an applicant’s noise measurement and evaluation methods must conform to those of Appendix A or to FAA approved equivalent procedures for compliance with the maximum noise level (noise limit) requirements of part 36 section B36.5.
b. Supplemental Information
None
c. Procedure
None
292. 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.
a. Explanation
XIV. APPENDIX B TO part 36--NOISE LEVELS FOR TRANSPORT CATEGORY AND JET AIRPLANES UNDER § 36.103
This section specifies that the noise evaluation metric to be used in showing compliance with the noise limits is the Effective Perceived Noise Level (in units of EPNdB). See section A36.4 for a description of EPNL and the methodology for its calculation.
b. Supplemental Information
None
c. Procedures
None
293. 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 August 7, 2002, 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 (6,500m) 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.
a. Explanation
This section specifies the locations of reference noise measurement points for flyover, lateral and approach noise measurements.
b. Supplemental Information
None
c. Procedures
None
294. 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.
a. Explanation
This section specifies FAA requirements when test noise measurement points are not located at reference noise measurement positions and the criteria for selection of lateral noise measurement points for jet airplanes and propeller-driven airplanes.
b. Supplemental Information
(1) Measured Lateral Noise Levels: Measured lateral noise levels may not be the same at symmetrical noise measurement points even when the data are adjusted for airplane position (for flight directly over the extended runway centerline). The direction of engine or propeller rotation may be an important factor in the non-symmetrical nature of measured lateral noise. Inlet shielding may cause turbojet-powered airplanes to exhibit 1-2 dB differences in lateral noise levels. Propeller-driven airplanes may exhibit differences in lateral noise levels in excess of 6 dB. Due to their inherent lateral noise asymmetry, for propeller-driven airplanes, section B36.4 requires that simultaneous measurements be made at each and every test noise measurement point at its symmetrical position on the opposite side of the runway.
(2) Maximum Lateral Noise Levels: An applicant may conduct noise measurements at several altitudes over symmetrically located noise measurement points in accordance with an FAA approved noise compliance demonstration plan to determine the maximum lateral noise levels. Typically, a 2nd order curve fit through the adjusted noise levels as a function of airplane altitude is sufficient to determine the maximum average lateral noise level and the altitude at which it occurred. Valid noise certification test data cannot be discarded.
(3) Maximum Lateral Noise Levels (Alternative Procedure): Section B36.3(a)(1) contains an alternative procedure whereby the maximum lateral noise level 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 (1427 feet for Stage 1 or Stage 2 four engine airplanes) altitude above ground level. Section 2.1.3.2 of the appended ICAO Environmental Technical Manual describes a similar equivalent procedure. However, unlike the ICAO TM equivalent procedure, use of the alternative procedure contained in section B36.3(a)(1) is not restricted to engines with bypass ratios of more than 2. Prior approval from the FAA is required to use this alternative procedure.
c. Procedure
(1) Applicant’s Responsibility: An applicant must include proposed equivalent procedures for lateral noise measurements in a noise compliance demonstration plan for FAA review and approval.
295. 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.
a. Explanation
This section specifies maximum noise levels (noise limits) at flyover, lateral and approach reference noise measurement points as a function of airplane maximum takeoff gross weight. For the flyover noise measurement point, the maximum noise levels (noise limits) are specified for the number of airplane engines as well as maximum weight.
b. Supplemental Information
(1) Stage Definitions: Definitions of Stage 1, Stage 2, and Stage 3 airplanes are given in section
36.1 of Subpart A.
(2) Acoustical Change: Requirements for FAA approval of Stage 1, Stage 2 and Stage 3 airplane Acoustical Changes, applied for under, Part 21.93(b) are specified in section 36.7 of Subpart A.
c. Procedures
(1) Maximum Noise Levels (Noise Limits): Flyover, lateral and approach maximum noise levels (noise limits) for Stage 2 and Stage 3 airplanes are given below. FAA uses Equations A through E to determine these levels (limits).
Stage No. of Engines Maximum Weight (MTOGW), pounds Flyover Limit, dB Lateral Limit, dB Approach Limit, dB 2 Any number 75,000 and less 93.0 102.0 102.0 2 Any number between 75,000 and 600,000 See Eqn. A See Eqn. B See Eqn. B 2 Any number 600,000 and more 108.0 108.0 108.0
3 Fewer than 3 106,250 and less 89.0
3 Fewer than 3 between 106,250 and 850,000 See Eqn. C 3 Fewer than 3 850,000 and more 101 3 Three 63,177 and less 89.0 3 Three between 63,177 and 850,000 See Eqn. C 3 Three 850,000 and more 104.0 3 More than 3 44,673 and less 89.0 3 More than 3 between 44,673 and 850,000 See Eqn. C 3 More than 3 850,000 and more 106.0 3 Any number 77,200 and less 94.0 3 Any number between 77,200 and 882,000 See Eqn. D 3 Any number 882,000 and more 103.0 3 Any number 77,200 and less 98.0 3 Any number between 77,200 and 617,300 See Eqn. E 3 Any number 617,300 and more 105.0
Eqn. A: Limit Flyover EPNL = 93.0 + 5.0 [(log (Maximum weight /75,000)) ÷ (log 2.0)] Eqn. B: Limit Approach EPNL = 102.0 + 2.0 [(log (Maximum weight /75,000)) ÷ (log 2.0)] Eqn. C: Limit Flyover EPNL = 89.0 + 4.0 [(log (Maximum weight / ‘K’)) ÷ (log 2.0)], where:
Number of Engines Eqn. C ‘K’ value Fewer than 3 106,250 Three 63,177 More than 3 44,673
Eqn. D: Limit Lateral EPNL = 94.0 + 2.56 [(log (Maximum weight /77,200)) ÷ (log 2.0)] Eqn. E: Limit Approach EPNL = 98.0 + 2.33 [(log (Maximum weight /77,200)) ÷ (log 2.0)]
Note: Maximum weights are considered to be the certificated maximum takeoff gross weight (MTOGW) at brake release for Flyover, Lateral and Approach noise measurement points
296. Section B36.6 Trade-Offs.
Except when prohibited by sections 36.7(c)(1) and 36.7(d)(1)(ii), if the maximum noise 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.
a. Explanation
This section specifies the noise level tradeoffs an applicant may use in demonstrating Stage 2 and Stage 3 compliance with part 36.
b. Supplemental Information
(1) Tradeoff Provisions: Tradeoffs are permitted in determining compliance with the Stage 2 and Stage 3 maximum noise level (noise limit) requirements of part 36 because of the cumulative aspects of noise