SPL 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 6300 8000 10000 60 0.59 1.00 1.40 1.81 2.08 2.51 2.93 3.26 3.57 4.00 4.00 4.00 4.00 4.00 4.59 6.01 6.90 7.92 8.49 8.49 7.92 7.39 6.01 4.89 61 0.67 1.10 1.53 1.97 2.26 2.71 3.16 3.51 3.83 4.29 4.29 4.29 4.29 4.29 4.92 6.44 7.39 8.49 9.09 9.09 8.49 7.92 6.44 5.24 62 0.77 1.21 1.66 2.15 2.45 2.93 3.41 3.78 4.11 4.59 4.59 4.59 4.59 4.59 5.28 6.90 7.92 9.09 9.74 9.74 9.09 8.49 6.90 5.61 63 0.87 1.32 1.81 2.34 2.65 3.16 3.69 4.06 4.41 4.92 4.92 4.92 4.92 4.92 5.66 7.39 8.49 9.74 10.4 10.4 9.74 9.09 7.39 6.01 64 1.00 1.45 1.97 2.54 2.88 3.41 3.98 4.38 4.73 5.28 5.28 5.28 5.28 5.28 6.06 7.92 9.09 10.4 11.2 11.2 10.4 9.74 7.92 6.44 65 1.11 1.60 2.15 2.77 3.12 3.69 4.30 4.71 5.08 5.66 5.66 5.66 5.66 5.66 6.50 8.49 9.74 11.2 12.0 12.0 11.2 10.4 8.49 6.90 66 1.22 1.75 2.34 3.01 3.39 3.98 4.64 5.07 5.45 6.06 6.06 6.06 6.06 6.06 6.96 9.09 10.4 12.0 12.8 12.8 12.0 11.2 9.09 7.39 67 1.35 1.92 2.54 3.28 3.68 4.30 5.01 5.46 5.85 6.50 6.50 6.50 6.50 6.50 7.46 9.74 11.2 12.8 13.8 13.8 12.8 12.0 9.74 7.92 68 1.49 2.11 2.77 3.57 3.99 4.64 5.41 5.88 6.27 6.96 6.96 6.96 6.96 6.96 8.00 10.4 12.0 13.8 14.7 14.7 13.8 12.8 10.4 8.49 69 1.65 2.32 3.01 3.88 4.33 5.01 5.84 6.33 6.73 7.46 7.46 7.46 7.46 7.46 8.57 11.2 12.8 14.7 15.8 15.8 14.7 13.8 11.2 9.09 70 1.82 2.55 3.28 4.23 4.69 5.41 6.31 6.81 7.23 8.00 8.00 8.00 8.00 8.00 9.19 12.0 13.8 15.8 16.9 16.9 15.8 14.7 12.0 9.74 71 2.02 2.79 3.57 4.60 5.09 5.84 6.81 7.33 7.75 8.57 8.57 8.57 8.57 8.57 9.85 12.8 14.7 16.9 18.1 18.1 16.9 15.8 12.8 10.4 72 2.23 3.07 3.88 5.01 5.52 6.31 7.36 7.90 8.32 9.19 9.19 9.19 9.19 9.19 10.6 13.8 15.8 18.1 19.4 19.4 18.1 16.9 13.8 11.2 73 2.46 3.37 4.23 5.45 5.99 6.81 7.94 8.50 8.93 9.85 9.85 9.85 9.85 9.85 11.3 14.7 16.9 19.4 20.8 20.8 19.4 18.1 14.7 12.0 74 2.72 3.70 4.60 5.94 6.50 7.36 8.57 9.15 9.59 10.6 10.6 10.6 10.6 10.6 12.1 15.8 18.1 20.8 22.3 22.3 20.8 19.4 15.8 12.8 75 3.01 4.06 5.01 6.46 7.05 7.94 9.19 9.85 10.3 11.3 11.3 11.3 11.3 11.3 13.0 16.9 19.4 22.3 23.9 23.9 22.3 20.8 16.9 13.8 76 3.32 4.46 5.45 7.03 7.65 8.57 9.85 10.6 11.0 12.1 12.1 12.1 12.1 12.1 13.9 18.1 20.8 23.9 25.6 25.6 23.9 22.3 18.1 14.7 77 3.67 4.89 5.94 7.66 8.29 9.19 10.6 11.3 11.8 13.0 13.0 13.0 13.0 13.0 14.9 19.4 22.3 25.6 27.4 27.4 25.6 23.9 19.4 15.8 78 4.06 5.37 6.46 8.33 9.00 9.85 11.3 12.1 12.7 13.9 13.9 13.9 13.9 13.9 16.0 20.8 23.9 27.4 29.4 29.4 27.4 25.6 20.8 16.9 79 4.49 5.90 7.03 9.07 9.76 10.6 12.1 13.0 13.6 14.9 14.9 14.9 14.9 14.9 17.1 22.3 25.6 29.4 31.5 31.5 29.4 27.4 22.3 18.1 80 4.96 6.48 7.66 9.85 10.6 11.3 13.0 13.9 14.6 16.0 16.0 16.0 16.0 16.0 18.4 23.9 27.4 31.5 33.7 33.7 31.5 29.4 23.9 19.4 81 5.48 7.11 8.33 10.6 11.3 12.1 13.9 14.9 15.7 17.1 17.1 17.1 17.1 17.1 19.7 25.6 29.4 33.7 36.1 36.1 33.7 31.5 25.6 20.8 82 6.06 7.81 9.07 11.3 12.1 13.0 14.9 16.0 16.9 18.4 18.4 18.4 18.4 18.4 21.1 27.4 31.5 36.1 38.7 38.7 36.1 33.7 27.4 22.3 83 6.70 8.57 9.87 12.1 13.0 13.9 16.0 17.1 18.1 19.7 19.7 19.7 19.7 19.7 22.6 29.4 33.7 38.7 41.5 41.5 38.7 36.1 29.4 23.9 84 7.41 9.41 10.7 13.0 13.9 14.9 17.1 18.4 19.4 21.1 21.1 21.1 21.1 21.1 24.3 31.5 36.1 41.5 44.4 44.4 41.5 38.7 31.5 25.6 85 8.19 10.3 11.7 13.9 14.9 16.0 18.4 19.7 20.8 22.6 22.6 22.6 22.6 22.6 26.0 33.7 38.7 44.4 47.6 47.6 44.4 41.5 33.7 27.4 86 9.95 11.3 12.7 14.9 16.0 17.1 19.7 21.1 22.4 24.3 24.3 24.3 24.3 24.3 27.9 36.1 41.5 47.6 51.0 51.0 47.6 44.4 36.1 29.4 87 10.0 12.1 13.9 16.0 17.1 18.4 21.1 22.6 24.0 26.0 26.0 26.0 26.0 26.0 29.0 38.7 44.4 51.0 54.7 54.7 51.0 47.6 38.7 31.5 88 11.1 13.0 14.9 17.1 18.4 19.7 22.6 24.3 25.8 27.9 27.9 27.9 27.9 27.9 32.0 41.5 47.6 54.7 58.6 58.6 54.7 51.0 41.5 33.7 89 12.2 13.9 16.0 18.4 19.7 21.1 24.3 26.0 27.7 29.9 29.9 29.9 29.9 29.9 34.3 44.4 51.0 58.6 62.7 62.7 58.6 54.7 44.4 36.1 90 13.5 14.9 17.1 19.7 21.1 22.6 26.0 27.9 29.7 32.0 32.0 32.0 32.0 32.0 36.8 47.6 54.7 62.7 67.2 67.2 62.7 58.6 47.6 38.7 91 14.9 16.0 18.4 21.1 22.6 24.3 27.9 29.9 31.8 34.3 34.3 34.3 34.3 34.3 39.4 51.0 58.6 67.2 72.0 72.0 67.2 62.7 51.0 41.5 92 16.0 17.1 19.7 22.6 24.3 26.0 29.9 32.0 34.2 36.8 36.8 36.8 36.8 36.8 42.2 54.7 62.7 72.0 77.2 77.2 72.0 67.2 54.7 44.4 93 17.1 18.4 21.1 24.3 26.0 27.9 32.0 34.3 36.7 39.4 39.4 39.4 39.4 39.4 45.3 58.6 67.2 77.2 82.7 82.7 77.2 72.0 58.6 47.6 94 18.4 19.7 22.6 26.0 27.9 29.9 34.3 36.8 39.4 42.2 42.2 42.2 42.2 42.2 48.5 62.7 72.0 82.7 88.6 88.6 82.7 77.2 62.7 51.0 95 19.7 21.1 24.3 27.9 29.9 32.0 36.8 39.4 42.2 45.3 45.3 45.3 45.3 45.3 52.0 67.2 77.2 88.6 94.9 94.9 88.6 82.7 67.2 54.7 96 21.1 22.6 26.0 29.9 32.0 34.3 39.4 42.2 45.3 48.5 48.5 48.5 48.5 48.5 55.7 72.0 82.7 94.9 102 102 94.9 88.6 72.0 58.6 97 22.6 24.3 27.9 32.0 34.3 36.8 42.2 45.3 48.5 52.0 52.0 52.0 52.0 52.0 59.7 77.2 88.6 102 109 109 102 94.9 77.2 62.7 98 24.3 26.0 29.9 34.3 36.8 39.4 45.3 48.5 52.0 55.7 55.7 55.7 55.7 55.7 64.0 82.7 94.9 109 117 117 109 102 82.7 67.2 99 26.0 27.9 32.0 36.8 39.4 42.2 48.5 52.0 55.7 59.7 59.7 59.7 59.7 59.7 68.6 88.6 102 117 125 125 117 109 88.6 72.0 100 27.9 29.9 34.3 39.4 42.2 45.3 52.0 55.7 59.7 64.0 64.0 64.0 64.0 64.0 73.5 94.9 109 125 134 134 125 117 94.9 77.2 101 29.9 32.0 36.8 42.2 45.3 48.5 55.7 59.7 64.0 68.6 68.6 68.6 68.6 68.6 78.8 102 117 134 144 144 134 125 102 82.7 102 32.0 34.3 39.4 45.3 48.5 52.0 59.7 64.0 68.6 73.5 73.5 73.5 73.5 73.5 84.4 109 125 144 154 154 144 134 109 88.6 103 34.3 36.8 42.2 48.5 52.0 55.7 64.0 68.6 73.5 78.8 78.8 78.8 78.8 78.8 90.5 117 134 154 165 165 154 144 117 94.9 104 36.8 39.4 45.3 52.0 55.7 59.7 68.6 73.5 78.8 84.4 84.4 84.4 84.4 84.4 97.0 125 144 165 177 177 165 154 125 102 105 39.4 42.2 48.5 55.7 59.7 64.0 73.5 78.8 84.4 90.5 90.5 90.5 90.5 90.5 104 134 154 177 189 189 177 165 134 109 106 42.2 45.3 52.0 59.7 64.0 68.6 78.8 84.4 90.5 97.0 97.0 97.0 97.0 97.0 111 144 165 189 203 203 189 177 144 117 107 45.3 48.5 55.7 64.0 68.6 73.5 84.4 90.5 97.0 104 104 104 104 104 119 154 177 203 217 217 203 189 154 125 108 48.5 52.0 59.7 68.6 73.5 78.8 90.5 97.0 104 111 111 111 111 111 128 165 189 217 233 233 217 203 165 134 109 52.0 55.7 64.0 73.5 78.8 84.4 97.0 104 111 119 119 119 119 119 137 177 203 233 249 249 233 217 177 144 110 55.7 59.7 68.6 78.8 84.4 90.5 104 111 119 128 128 128 128 128 147 189 217 249 267 267 249 233 189 154 111 59.7 64.0 73.5 84.4 90.5 97.0 111 119 128 137 137 137 137 137 158 203 233 267 286 286 267 249 203 165 112 64.0 68.6 78.8 90.5 97.0 104 119 128 137 147 147 147 147 147 169 217 249 286 307 307 286 267 217 177 113 68.6 73.5 84.4 97.0 104 111 128 137 147 158 158 158 158 158 181 233 267 307 329 329 307 286 233 189 114 73.5 78.8 90.5 104 111 119 137 147 158 169 169 169 169 169 194 249 286 329 352 352 329 307 249 203 115 78.8 84.4 97.0 111 119 128 147 158 169 181 181 181 181 181 208 267 307 352 377 377 352 329 267 217 116 84.4 90.5 104 119 128 137 158 169 181 194 194 194 194 194 223 286 329 377 404 404 377 352 286 233 117 90.5 97.0 111 128 137 147 169 181 194 208 208 208 208 208 239 307 352 404 433 433 404 377 307 249 118 97.0 104 119 137 147 158 181 194 208 223 223 223 223 223 256 329 377 433 464 464 433 404 329 267 119 104 111 128 147 158 169 194 208 223 239 239 239 239 239 274 352 404 464 497 497 464 433 352 286 120 111 119 137 158 169 181 208 223 239 256 256 256 256 256 294 377 433 497 533 533 497 464 377 307 121 119 128 147 169 181 194 223 239 256 274 274 274 274 274 315 404 464 533 571 571 533 497 404 329 122 128 137 158 181 194 208 239 256 274 294 294 294 294 294 338 433 497 571 611 611 571 533 433 352 123 137 147 169 194 208 223 256 274 294 315 315 315 315 315 362 464 533 611 655 655 611 571 464 377 124 147 158 181 208 223 239 274 294 315 338 338 338 338 338 388 497 571 655 702 702 655 611 497 404 125 158 169 194 223 239 256 294 315 338 362 362 362 362 362 416 533 611 702 752 752 702 655 533 433 Page 109
SPL 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 6300 8000 10000 126 169 181 208 239 256 274 315 338 362 388 388 388 388 388 446 571 655 752 806 806 752 702 571 464 127 181 194 223 256 274 294 338 362 388 416 416 416 416 416 478 611 702 806 863 863 806 752 611 497 128 194 208 239 274 294 315 362 388 416 446 446 446 446 446 512 655 752 863 925 925 863 806 655 533 129 208 223 256 294 315 338 388 416 446 478 478 478 478 478 549 702 806 925 991 991 925 863 702 571 130 223 239 274 315 338 362 416 446 478 512 512 512 512 512 588 752 863 991 1062 1062 991 925 752 611 131 239 256 294 338 362 388 446 478 512 549 549 549 549 549 630 806 925 1062 1137 1137 1062 991 806 655 132 256 274 315 362 388 416 478 512 549 588 588 588 588 588 676 863 991 1137 1219 1219 1137 1062 863 702 133 274 294 338 388 416 446 512 549 588 630 630 630 630 630 724 925 1062 1219 1306 1306 1219 1137 925 752 134 294 315 362 416 446 478 549 588 630 676 676 676 676 676 776 991 1137 1306 1399 1399 1306 1219 991 806 135 315 338 388 446 478 512 588 630 676 724 724 724 724 724 832 1062 1219 1399 1499 1499 1399 1306 1062 863 136 338 362 416 478 512 549 630 676 724 776 776 776 776 776 891 1137 1306 1499 1606 1606 1499 1399 1137 925 137 362 388 446 512 549 588 676 724 776 832 832 832 832 832 955 1219 1399 1606 1721 1721 1606 1499 1219 991 138 388 416 478 549 588 630 724 776 832 891 891 891 891 891 1024 1306 1499 1721 1844 1844 1721 1606 1306 1062 139 416 446 512 588 630 676 776 832 891 955 955 955 955 955 1098 1399 1606 1844 1975 1975 1844 1721 1399 1137 140 446 478 549 630 676 724 832 891 955 1024 1024 1024 1024 1024 1176 1499 1721 1975 1975 1844 1499 1219 141 478 512 588 676 724 776 891 955 1024 1098 1098 1098 1098 1098 1261 1606 1844 1975 1606 1306 142 512 549 630 724 776 832 955 1024 1098 1176 1176 1176 1176 1176 1351 1721 1975 1721 1399 143 549 588 676 776 832 891 1024 1098 1176 1261 1261 1261 1261 1261 1448 1844 1844 1499 144 588 630 724 832 891 955 1098 1176 1261 1351 1351 1351 1351 1351 1552 1975 1975 1606 145 630 676 776 891 955 1024 1176 1261 1351 1448 1448 1448 1448 1448 1664 1721 146 676 724 832 955 1024 1098 1261 1351 1448 1552 1552 1552 1552 1552 1783 1844 147 724 776 891 1024 1098 1176 1351 1448 1552 1664 1664 1664 1664 1664 1911 1975 148 776 832 955 1098 1176 1261 1448 1552 1664 1783 1783 1783 1783 1783 2048 149 832 891 1024 1176 1261 1351 1552 1664 1783 1911 1911 1911 1911 1911 150 891 955 1098 1261 1351 1448 1664 1783 1911 2048 2048 2048 2048 2048 Page 110
Table 10. Example of tone correction calculation for a turbotan engine SPL" dB dB dB Band SPL Step Step Step Step Step
(1) Hz dB 7 8 1 50 63 80 70 70 -8 —2⅓ 70 100 62 62 -8 +3·⅓ 67⅓ 125 16 71 +9 +6⅓ 71 6 160 80 +10 2 80 +9 +2⅓ 77⅓ 2⅓ 0.29 200 82 82 +2 -1⅓ 80⅓ 1⅓ 0.Õ6 250 +1 79 -3 —1 ⅕ 79 4 0.61 315 76 76 -3 77⅔ 10 400 11 78 +2 +1 78 2 0.17 11 500 80 4 80 +2 79 — 12 630 79 -1 79 -1 79 13 800 78 -1 78 —1 —⅓ 79 14 1 000 80 +2 80 +2 78⅔ 15 1 250 78 -2 4 78 -2 —⅓ 78 16 1 600 76 -2 76 -2 +⅓ 77% 17 2 000 79 +3 5 79 +3 +1 78 18 2 500 79 —·⅓ 79 2 19 3 150 79 12 79 -2⅓ 78⅔ 20 4 000 78 -1 5 78 -1 —6⅓ 76 2 0.33 21 5 000 71 6 71 -8 69⅔ 22 6 300 60 -11 4 60 -11 -8⅓ 61⅓ 23 8 000 54 54 -8 53 24 10 000 45 45 45 Step 1 ⅓)(-1) Step 6 Step 2 Step 7 Q(-1)+%(-1) Step 3 see instructions Step 8 Step 4 see instructions Step 9 see Table A36-2 Step 5 (a)(û(&) (-1) Note. — Steps 5 and 6 may be eliminated in the calculations if desired. In this case in the example shown, columns, and e should be removedand existing column (a) un) andy) become 2) • (a) and (a) coveringnew steps 5, 6 and 7 respectively. The existing steps5, 6,7, 8 and 9 in 4.3.1 of Appendix Aarethenreplacedby:
STEPS 6 (1- 1) + 1(0 (ı+1)]÷3 STEO (1) -Q (i) if>0 STEP 7 See Table A36-2.
1 10 100 1 000 10 000 Total perceived noisiness, , noys N Perceived noise level, PNL, PNdB 150 140 130 120 110 100 90 80 70 60 50 40 Figure 7. Perceived noise level as a function of total perceived noisiness Page 112
Chapter 4
GUIDELINES FOR TRANSPORT CATEGORY LARGE AIRPLANES, SUBSONIC JETAIRPLANES, AND HELICOPTERS EVALUATED UNDER APPENDIX A OR H OF 14 CFR PART 36
CHAPTER TABLE OF CONTENTS
401 EXPLANATORY INFORMATION116
401(a) Noise Measurements116
401(b) Noise Certification Test and Measurement Conditions116
401(b)(1) Ambient temperature116
401(b)(2) Calculation of sound attenuation coefficients for the effects of atmospheric absorption117
401(b)(3) Wind speed120
401(b)(4) Anomalous meteorological conditions121
401(b)(5) Time of meteorological measurements121
401(b)(6) Aircraft position measurement122
401(b)(7) Time space position information (TSPI) measurement system characteristics122
401(b)(8) Aircraft performance123
401(c) Measurement of Aircraft Noise Received on the Ground124
401(c)(1) Environmental specifications124
401(c)(2) Measurement system specification124
401(c)(3) Microphone orientation124
401(c)(4) Microphone specification124
401(c)(5) Recorder specifications125
401(c)(6) Pre-emphasis127
401(c)(7) Attenuator specifications127
401(c)(8) Linear integrating analyzer specifications127
401(c)(9) Analyzer performance specifications127
401(c)(10) Microphone incidence adjustments128
401(c)(11) Pink noise specification128
401(c)(12) Measurement system field calibration128
401(c)(13) Field acoustical calibrations128
401(c)(14) Windscreen loss adjustment129
401(c)(15) Measurement system background noise129
401(d) Calculation of EPNL from Measured Data129
401(d)(1) Instantaneous sound pressure levels129
401(d)(2) Tone correction calculation130
401(d)(3) Adjustments relating to background noise130
401(d)(4) Data resolution after tone correction calculation130
401(d)(5) Band sharing adjustment130
401(d)(6) Calculation of band sharing adjustment131
401(d)(7) Noise Duration131
401(d)(8) Equations for computing duration correction132
401(e) Reporting of Data to the FAA133
401(e)(1) Compliance records133
401(e)(2) EPNL average values133
401(e)(3) Calculation of 90 percent confidence intervals134
401(f) Nomenclature: Symbols and Units134
401(g) Sound Attenuation in Air135
401(h) Adjustment of Helicopter Flight Test Results135
401(h)(1) Adjustments to reference conditions135
401(h)(2) Reference data sources136
401(h)(3) Adjustments to measured noise data136
401(h)(4) Takeoff profile136
401(h)(5) Takeoff test conditions137
401(h)(6) Takeoff flight test procedures139
401(h)(7) Flyover configuration142
401(h)(8) Flyover test procedure144
401(h)(9) Approach configuration148
401(h)(10) Approach test condition149
401(h)(11) Approach test procedure150
401(h)(12) Adjustments of PNL and PNLT152
401(h)(13) Duration adjustment to EPNL152
401(i) Adjustment of Airplane Flight Test Results153
401(i)(1) Adjustments to reference conditions153
401(i)(1)(A) Origin of reference data154
401(i)(2) Takeoff configuration/profile154
401(i)(3) Takeoff test procedure157
401(i)(4) Approach test configuration157
401(i)(5) Approach test procedure159
401(i)(6) Lateral noise measurement160
401(i)(7) Integrated procedure adjustment160
401(i)(8) Acoustic emission angles160
402 EQUIVALENT PROCEDURES INFORMATION160
402(a) Subsonic Jet Airplanes160
402(a)(1) Flight test procedures161
402(a)(1)(A) Flight path intercepts161
402(a)(1)(A)(i) For takeoff161
402(a)(1)(A)(ii) For approach161
402(a)(1)(B) Generalized flight test procedures162
402(a)(1)(B)(i) For derivation of noise-power-distance (NPD) data162
402(a)(1)(B)(ii) For flight test procedures for determination of changes164
402(a)(1)(C) Determination of the lateral certification noise levels164
402(a)(1)(D) Takeoff flyover noise levels with thrust (power) reduction165
402(a)(1)(E) Measurements at non-reference points166
402(a)(1)(F) Atmospheric test conditions166
402(a)(1)(G) Layering equivalency166
402(a)(2) Analytical procedures167
402(a)(2)(A) Flyover noise levels with thrust (power) reduction167
402(a)(2)(B) Equivalent procedures based upon analytical methods168
402(a)(2)(C) Equivalent procedure for calculating the certification noise levels169
402(a)(3) Static engine noise tests and projections to flight noise levels170
402(a)(3)(A) General170
402(a)(3)(B) Limitation on the projection of static-to-flight data170
402(a)(3)(C) Static engine noise test procedures172
402(a)(3)(C)(i) General172
402(a)(3)(C)(ii) Test site characteristics172
402(a)(3)(C)(iii) Data acquisition and reduction systems173
402(a)(3)(C)(iv) Microphone types, locations and installations174
402(a)(3)(D) Projection of static engine data to airplane flight conditions174
402(a)(3)(D)(i) General174
402(a)(3)(D)(ii) Normalization to reference conditions176
402(a)(3)(D)(iii) Separation into broadband and tone noise177
402(a)(3)(D)(iv) Separation into contributing noise sources177
402(a)(3)(D)(v) Noise source position effects178
402(a)(3)(D)(vi) Engine flight conditions179
402(a)(3)(d)(vii) Noise source motion effects179
402(a)(3)(D)(viii) Airplane configuration effects180
402(a)(3)(D)(ix) Airframe noise181
402(a)(3)(D)(x) Airplane flight path considerations181
402(a)(3)(D)(xi) Total noise spectra181
402(a)(3)(D)(xii) EPNL computations182
402(a)(3)(D)(xiii) Changes to noise levels182
402(b) Propeller-Driven Airplanes Over 19,000 lb182
402(b)(1) Flight test procedures182
402(b)(1)(A) Flight path intercept procedures182
402(b)(1)(B) Generalized flight test procedures182
402(b)(1)(C) Determination of the lateral certification noise level183
402(b)(1)(D) Measurements at non-reference points184
402(b)(2) Analytical procedures185
402(b)(3) Ground static testing procedures186
402(b)(3)(A) General186
402(b)(3)(B) Guidance on the test-site characteristics186
402(b)(3)(C) Static tests of the gas generator186
402(c) Helicopters186
402(c)(1) Flight test procedures187
402(c)(1)(A) Helicopter test speed187
402(c)(1)(B) Atmospheric test conditions187
402(c)(1)(C) Temperature and relative humidity measurements187
402(c)(1)(D) Modifications or upgrades involving aerodynamic drag changes188
402(c)(1)(E) Anomalous test conditions188
402(c)(1)(F) Helicopter test rotor speed189
402(c)(1)(G) Helicopter test weight189
402(c)(1)(H) Helicopter approach189
402(c)(2) Analytical procedures189
402(c)(2)(A) Helicopter test window for zero adjustment for atmospheric attenuation189
402(c)(2)(B) Procedure for the determination of source noise adjustment191
403 TECHNICAL PROCEDURES INFORMATION192
403(a) Jet and Propeller-Driven Airplanes and Helicopters192
403(a)(1) Adjustment of measured noise data to reference conditions192
403(a)(2) Determination of reference-condition noise geometry192
403(a)(2)(A) Assumptions193
403(a)(2)(B) Steps involved193
403(a)(2)(C) Characterization of a straight-line average flight path based on descriptors193
403(a)(2)(D) Determination of test aircraft position at time of sound emission195
403(a)(2)(E) Calculation of the geometric minimum distance between the test flight path197
403(a)(2)(F) Determination of test aircraft noise geometry200
403(a)(2)(G) Determination of reference flight path201
403(a)(2)(H) Determination of reference sound propagation distance202
403(a)(2)(I) Determination of effective duration for each acoustic spectrum203
403(a)(3) Computation of EPNL by the simplified method of adjustment205
403(a)(3)(A) Inputs required for performing the simplified method205
403(a)(3)(B) Adjustment of sound pressure levels to reference conditions206
403(a)(3)(C) Determination of reference-condition tone-corrected perceived noise levels206
403(a)(3)(D) Application of test-day bandsharing adjustment to reference-condition206
403(a)(3)(E) Determination of the ΔPeak simplified adjustment term to account for the effects207
403(a)(3)(G) Determination of the Δ3 simplified adjustment term to account for differences207
403(a)(3)(H) Determination of the simplified reference-condition effective perceived noise level208
403(a)(3)(I) Worked example calculations illustrating the simplified method208
403(a)(4) Computation of EPNL by the integrated method of adjustment208
403(a)(4)(A) Inputs required for performing the integrated method208
403(a)(4)(B) Adjustment of sound pressure levels to reference conditions209
403(a)(4)(C) Determination of reference-condition tone-corrected perceived noise209
403(a)(4)(D) Identification of integrated reference-condition maximum tone-corrected209
403(a)(4)(E) Identification of integrated reference-condition EPNL Noise Duration210
403(a)(4)(F) Summation of integrated reference-condition EPNL210
403(a)(4)(G) Worked example calculations illustrating the integrated method210
403(b) Jet Airplanes211
403(b)(1) Control of noise certification computer program software and documentation211
403(b)(1)(A) General211
403(b)(1)(B) Software control procedures — four key elements212
403(b)(1)(B)(i) Configuration index212
403(b)(1)(B)(ii) Software control plan212
403(b)(1)(B)(iii) Design description212
403(b)(1)(B)(iv) Verification process212
403(b)(1)(C) Applicability212
403(b)(2) Identification of spectral irregularities212
403(b)(2)(A) Introduction213
403(b)(2)(B) Methods for identifying false tones213
403(b)(2)(B)(i) Frequency tracking213
403(b)(2)(B)(ii) Narrow-band analysis214
403(b)(2)(B)(iii) Microphone mounting height214
403(b)(2)(B)(iv) Inspection of noise time-histories214
403(b)(2)(C) Treatment of false tones214
403(b)(3) Noise data adjustments for tests at high altitude test sites214
403(b)(3)(A) Introduction214
403(b)(3)(B) Jet source noise adjustment214
403(b)(3)(B)(i) Criteria215
403(b)(3)(B)(ii) Adjustment procedures215
EXPLANATORY INFORMATION [ETM 4.1] Noise Measurements 401(a) §A36.2 [ETM 4.1.1] See 301 for technical procedures generally applicable for noise certification tests of all aircraft types including those evaluated under the provisions of Appendices A or H of part 36. Procedures specific to Appendix A or H are presented in the following section.
Noise Certification Test and Measurement Conditions 401(b) §A36.2 [ETM 4.1.2] 401(b)(1) Ambient temperature GM §A36.2.2.2(b) [ETM GM A2 2.2.2.4.1 b)]
(1) Criteria for measuring atmospheric conditions Experience has shown that proper measurement of non-r eference meteorological conditions and the associated adjustment of noise data for these conditions are crucial to obtaining accurate, consistent and repeatable test results. For airplanes, meteorological observations of the temperature and relative humidity are required over the whole sound propagation path from the aircraft to the vicinity of the noise measurem ent points. For helicopters, temperature and relative humidity measurements are require d at 33 ft (10 m) in the vicinity of the noise measurement points.
AMC §A36.2.2.2(b) [ETM AMC A2 2.2.2.4.1 b)] Page 116
(1) Atmospheric measurements Several methods have been approved for the measurement of atmospheric conditions from 33 ft (10 m) above the ground to the altitude of the test airplane. Some appli cants have used instrument ed balloons. Another method consists of a meteorological airplane, manned or unmanned, flown in a spiral flight path in the vicinity of the noise measurement points to measure the dry bulb temperature and dew point along the sound propagation path.
401(b)(2) Calculation of sound attenuation coefficients for the ef fects of atmospheric absorption AMC §A36.2.2.2(d) [ETM AMC A2 2.2.2.2.1)]
(1) Basic data Measurements of the ambient temperature and relative humidity should be made at 33 ft (10 m) above the ground.
The ambient temperature and relative humidity should also be determined with vertical height increments not greater than 100 ft (30 m) over the sound propagation path. All measurements of ambient temperature and relative humidity must be obtained within 30 minutes of each airplane test run.
(2) Determination of the average sound attenuation coefficient Table 11 is an example of calculation of sound attenuation coefficients in the 3150 Hz one-third octave band for an airplane approach noise certification when multiple layering is not required. Temperature and humidity values obtained from atmospheric soundings performed before and after a series of airplane test runs are interpolated to the time of PNLTM.
Table 11. Basic data (layering not required) Height Temperature Relative humidity α (3150 Hz)
(m) (°C) (%) (dB/100 m) 10 14.1 50 2.45 30 13.4 53 2.38 60 12.9 56 2.30 90 12.2 57 2.33 120 11.5 58 2.37 150 11.3 61 2.27 The individual coefficients shown in Table 11are calculated at vertical height increments of 30 m from 10 m to a height of 150 m. The ambient conditions from the ground to 10 m are assumed to be those measured at 10 m.
The individual sound attenuation coefficients for the 3150 Hz one-third octave band shown in Table 11 vary by less than 0.5 dB/100 m relative to the value determined at 10 m (33 ft). In this case the coefficient to be used for adjustment of sound pressure levels fr om test to reference conditions is the average of the coefficients at 10 m (33 ft) and at the height of the airplane at the time of PNLTM.
For this example, the height of the test airplane at the time of PNLTM is 125 m. The associated attenuation Page 117
coefficient is calculated by linear interpolation as follows:
ݕൌ ݕ ሺݔെݔ ሻ ∗ሺ ݕ െݕ ሻሺݔ െݔ ሻ ߙሺ3150ሻଵଶହ ൌ2 . 3 7 ሺ125 െ 120ሻ ∗ ሺ2.27 െ 2.37ሻሺ150 െ 120ሻ ߙሺ3150ሻଵଶହ ൌ 2.35/ܤ݀100݉ .
Then the average attenuation coefficient for the 3150 Hz one-third octave band used for adjustment of the airplane sound pressure levels is calculated as follows:
ߙሺ3150ሻ ൌ ߙሺ3150ሻଵ ߙሺ3150ሻଵଶହ 2 ߙሺ3150ሻ ൌ 2.45 2.352 ߙሺ3150ሻ ൌ 2.40/ܤ݀100݉ .
The coefficients for the other one-third octave band s are determined in a similar manner. These average coefficients are then used in the adjustment of airplane SPLs to reference conditions. The same general procedure would be used if no layering was required for determin ing the average coefficients during flyover and lateral noise certification measurements.
(3) Determination of the cumulative sound attenuation coefficients Table 12 is an example of calculation of sound attenuation coefficients in the 3150 Hz one-third octave band for an airplane flyover noise certification when multiple layering is required. Temperature and humidity values obtained from atmospheric soundings performed before and after a series of airplane test runs are interpolated to the time of PNLTM.
Table 12. Basic data (layering required) Height Temperature Relative humidity α (3 150 Hz)
(m) (°C) (%) (dB/100 m) 10 7.2 80 2.09 30 7.2 75 2.23 60 8.9 73 2.11 90 10.0 67 2.19 120 10.6 63 2.27 150 10.6 62 2.31 180 10.6 61 2.34 210 10.6 59 2.43 240 11.1 55 2.57 270 11.7 53 2.59 Page 118
Height
(m) 300 330 360 390 420 Temperature (°C)
11.7
11.1
11.1
11.1
11.1 Relative humidity (%) 51 51 50 47 46 α (3 150 Hz) (dB/100 m)
2.70
2.79
2.84
3.04
3.10 The individual coefficients shown in Table 12 are calculated at vertical height increments of 30 m from 10 m to a height of 420 m. The ambient conditions from the ground to 10 m are assumed to be those measured at 10 m.
The individual sound attenuation coefficients for the 3150 Hz one-third octave band shown in Table 12 vary by more than 0.5 dB/100 m. In this case the coefficient to be used for adjustment of sound pressure levels from test to reference conditions is the cumulative sound attenuation from the ground to the height of the airplane at the time of PNLTM.
In the absence of extreme or anomalous conditions (e.g., large variations in, or inversions of, temperature and/or humidity), which will generally be the case, it is acceptable, subject to the approval by the FAA, to determine the cumulative sound attenuation coefficients for each one-third octave band from a simple average of the coefficients at the boundaries of each layer.
Where extreme or anomalous conditions are present (e.g., large variations in, or inversions of, temperature and/or humidity) the cumulative sound attenuation coefficients for each one-third octave band should be determined by apportioning the sound attenuation coefficients for each layer. Table 13 illustrates an example of such a method.
Table 13. Determination of the cumulative sound attenuation Average layer Apportioned Effective sound sound Effective layer Sound attenuation attenuation attenuation layer depth coefficients, coefficients, coefficients, Layer depth proportion α (3 150 Hz) α (3 150 Hz) α (3 150 Hz) boundaries (m) (%) (dB/100 m) (dB/100 m) (dB/100 m) 0–30 28.8 7.03 2.09–2.23 2.16 0.1518 30–60 30.0 7.32 2.23–2.11 2.17 0.1589 60–90 30.0 7.32 2.11–2.19 2.15 0.1574 90–120 30.0 7.32 2.19–2.27 2.23 0.1633 120–150 30.0 7.32 2.27–2.31 2.29 0.1676 150–180 30.0 7.32 2.31–2.34 2.32 0.1698 180–210 30.0 7.32 2.34–2.43 2.39 0.1750 210–240 30.0 7.32 2.43–2.57 2.50 0.1830 240–270 30.0 7.32 2.57–2.59 2.58 0.1889 270–300 30.0 7.32 2.59–2.70 2.65 0.1940 300–330 30.0 7.32 2.70–2.79 2.74 0.2006 330–360 30.0 7.32 2.79–2.84 2.82 0.2064 Page 119
Average layer Apportioned Effective sound sound Effective layer Sound attenuation attenuation attenuation layer depth coefficients, coefficients, coefficients, Layer depth proportion α (3 150 Hz) α (3 150 Hz) α (3 150 Hz) boundaries (m) (%) (dB/100 m) (dB/100 m) (dB/100 m) 360–390 30.0 7.32 2.84–3.04 2.94 0.2152 390–411 21.0 5.12 3.04–3.08 3.06 0.1568 Cumulative 2.49 sound attenuation coefficient, α (3150 Hz) (dB/100 m):
The atmosphere is first divided into layers from the ground to the airplane height. For this example the height of the airplane at the time of PNLTM is 411 m.
The sound attenuation coefficient at the height of the test airplane is calculated by linear interpolation of the sound attenuation coefficients at the upper and lower boundaries of the uppermost layer.
The effective layer depth is determined as follows: for all layers between the airplane and the microphone, except the lowest layer containing the microphone and the upperm ost layer containing the airplane, the effective layer depth is the full 30 m; for the lowest layer containing the microphone, the effective layer depth is 30 m minus the
1.2 m height of the microphone; for the uppermost layer containing the airplane, the effective layer depth is the height of the airplane minus the height of the lower boundary of the layer.
The effective layer depth proportion for each layer is determined as the ratio of that layer’s effective depth relative to the total vertical component of the sound propagation distance from the microphone to the height of the airplane at the time of PNLTM.
The average sound attenuation coefficient for each layer is obtained by averaging the coefficients at the upper and lower boundaries of the layer.
The apportioned sound attenuation coefficient for each layer is obtained by multiplying the average layer sound attenuation coefficient by the effective layer depth proportion.
The summation of all apportioned sound attenuation coefficients results in the cumulative sound attenuation coefficient. In this example the cumulative coefficient is calculated for the 3 150 Hz one-third octave band. The same general procedure would be used to obtain the cumulative sound attenuation coefficient for each one-third octave band. These coefficients are then used in the adjustment of airplane SPLs to reference conditions.
401(b)(3) Wind speed AMC §A36.2.2.2(e) [ETM AMC A2 2.2.2.4.1 e) f) g) h)]
(1) Real-time crosswind component measurements Applicants are advised to provide ap proved real-time crosswind component measurement systems such that the crosswind component speeds can be verified after each aircraft test run. When the applicant uses a wind measurement system that is remotely located and not readily accessible, such as chart recorders that simultaneously and independently measure and record wind speed and direction, it may not be practical to determine the real-time crosswind component for each test run. For airplanes, if the applicant does not provide an acceptable real-time crosswind component measurement system, the 10 kt (5.1 m/s) maximum crosswind component and the 7 kt (3.6 m/s) average crosswind component become the maximum wind limitations regardless of wind direction.