____ to give the customers the details they need for the calculation program.
(a) If computation is possible, use the CFM trim balance program CFM56 MULTI - ENGINE TRIM BALANCE PROGRAM 856A2650G10 or G11 or G12 or CFM56 MULTI - ENGINE TRIM BALANCE PROGRAM 856A2678P01.
(b) If not, do calculation as instructed in the following steps.
(3) Fill in the table. See example: (Ref. Fig. 521/TASK 71-00-00-991-351, 522/TASK 71-00-00-991-352)
(4) After installation of the weight obtained through one-shot calculation, the initial vibrations noted AB for the 3 speeds become vibrations AC. The engine response is determined by measuring vibrations BC on a polar graph.
(5) On a polar graph, using a mils scale, plot the initial and final vibration for the maximum speed. See example: (Ref. Fig. 523/TASK 71-00-00-991-353)
(6) Using compasses, do as follows.
(a) Take the length of vector BA and draw a circle with radius BA and center C.
(b) Take the length of vector BC and draw a circle with radius BC and center A. The vector which passes through the origin of the polar graph and the intersection point of the circles is parallel and equal to BC.
(7) Measure the length and the angle of vector BC. Example: The engine response at 96 percent N1 is 4.5 mils at 15 degrees. (Ref. Fig. 523/TASK 71-00-00-991-353)
(8) Record this value in the table.
(Ref. Fig. 521/TASK 71-00-00-991-351)
See example:
(Ref. Fig. 524/TASK 71-00-00-991-356)
(9) Use the same procedure for 84 percent N1 and 64 percent N1. (Ref. Fig. 525/TASK 71-00-00-991-354, 526/TASK 71-00-00-991-355)
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Engine Sensitivity Calculation Chart
Figure 521/TASK 71-00-00-991-351
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Measurement Recording Example Figure 522/TASK 71-00-00-991-352
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Determination of Engine Vibration Response at 96 percent N1 Figure 523/TASK 71-00-00-991-353
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Engine Sensitivity Calculation Chart - Calculation Example
Figure 524/TASK 71-00-00-991-356
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Determination of the Engine Vibration Response at 84 percent N1 Figure 525/TASK 71-00-00-991-354
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Determination of the Engine Vibration Response at 62 percent N1 Figure 526/TASK 71-00-00-991-355
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(10) On a polar graph, determine the actual weight added between the two flights as follows.
(a) Plot the initial weight (for example: 236 g.cm at 229 degrees). (Ref. Fig. 527/TASK 71-00-00-991-357)
(b) Plot the weight actually installed on the spinner for the other flight (for example: 604 g.cm at 275 degrees).
(11) Draw two arcs as follows:
(a) One arc with the end of the second vector (second weight) as center and the length of the first vector (first weight) as radius.
(b) One arc with the origin of the graph as center and the line connecting the 2 vectors as radius. Then note the value and the angle of the weight actually added (Example: 479 g.cm at 296 degrees).
(12) The engine sensitivity at each speed is obtained by dividing the weight actually added by the vibration response at each speed. Example:
96 percent of N1 S = 479 g.cm/4.5 mils = 107 g.cm/mils 84 percent of N1 S = 479 g.cm/3.1 mils = 152 g.cm/mils 64 percent of N1 S = 479 g.cm/1.1 mils = 432 g.cm/mils
(13) The engine phase lag is obtained by adding the following angles: Angle of the added weight + angle of the vibration response + 180 degrees. Example:
96 percent = PL = 296 + 15 + 180 = 491 i.e. 131 degrees 84 percent = PL = 296 + 359 + 180 = 835 i.e. 115 degrees 64 percent = PL = 296 + 15 + 180 = 491 i.e. 131 degrees
(14) Record the calculated values in the table (Ref. Fig. 528/TASK 71-00-00-991-358) See example: (Ref. Fig. 529/TASK 71-00-00-991-359) 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：A320飞机维护手册 AMM 动力装置 POWER PLANT 1(68)
