14 CFR Ch. I (1-1-19 Edition) arithmetically to the EPNL value calculated from the measured data. A36.9.3.5 Symmetry adjustments. A36.9.3.5.1 A symmetry adjustment to each lateral noise value (determined at the section B36.4(b) measurement points), is to be made as follows: (a) If the symmetrical measurement point is opposite the point where the highest noise level is obtained on the main lateral measurement line, the certification noise level is the arithmetic mean of the noise levels measured at these two points (see Figure A36-9(a)); (b) If the condition described in paragraph (a) of this section is not met, then it is assumed that the variation of noise with the altitude of the airplane is the same on both sides; there is a constant difference between the lines of noise versus altitude on both sides (see figure A36-9(b)). The certification noise level is the maximum value of the mean between these lines. A36.9.4 Integrated method of adjustment A36.9.4.1 General. As described in this section, the integrated adjustment method consists of recomputing under reference conditions points on the PNLT time history corresponding to measured points obtained during the tests, and computing EPNL directly for the new time history obtained in this way. The main principles are described in sections A36.9.4.2 through A36.9.4.4.1. 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: 802 VerDate Sep<11>2014 12:50 Apr 30, 2019 Jkt 247046 PO 00000 Frm 00812 Fmt 8010 Sfmt 8002 Y:\SGML\247046.XXX 247046 ER08JY02.019 spaschal on DSK3GDR082PROD with CFR Pt. 36, App. A