TM 1-1520-238-T-4 5–60 Change 9 5–23. TAIL ROTOR BALANCE – MAINTENANCE OPERATIONAL CHECK USING 5–23 AVA EQUIPMENT (cont) k. Enter the MEASURE mode by pressing F1. Verify that test state FPGTL is highlighted. l. Press DO when aircraft is stable at highlighted selection. Reverify that aircraft is at required test state and press DO again. AVA will acquire balance data and return to selection menu. m. After measurement is completed, press DO on “finish”, then press DO on “diagnostics”. If measurements are within specified limits, press QUIT to main menu. n. If results are less than 0.2 ips, no corrections are required. However, AVA may offer corrections to smooth rotor further, at operator’s discretion. Even though limit is 0.2 ips, tail rotor can achieve 0.1 ips or below in most cases, and is recommended to try and obtain the 0.1 ips goal. o. If measured values exceed specifications, press DO and perform corrections as shown. p. Perform tail measurement again and verify corrections. 2. COMPARE MOVES BETWEEN RUNS a. It is always recommended to compare the vibration from one measurement to the next (mainly to ensure that the aircraft is responding in a normal manner). For the TAIL flight plan there is only one reading to trend. To trend this, perform the following: With the latest flight id picked enter the Display mode by pressing F2. Select Trend Flights and press DO. Press DO on 1T POLAR. Enter the number of test states to trend (the easiest to understand is just trend the last two flights by entering 2, this will trend the most current flight with the previous flight), then arrow down to Draw Axis and change to NO by pressing the right arrow (this will make the polar chart easier to read), and then press DO. b. This will display a vibration trend from the latest reading with previous readings on a polar chart. This process is displayed in Figure 5–27. One Test State Complete Flight View Limits Summary Displays Display Mode Trend Flights [ DO ] Select Options 1T POLAR DISPLAYS DO–Select QUIT – Exit Enter the number of tests to show on the polar plot at one time. No. of Test: 2 [UP] [LEFT] [DO] & & Save & Exit [DOWN] [RIGHT] Arrows Arrows [QUIT] Draw Axis = NO Entry Form 0.50 AH64 24210 CURRENT 10:10:00 11 MAR 94 ID FLT AMP [ips] PHASE [deg] FPGTL 1T A B CURRENT 09:30 0.07 0.26 18.23 306.12 A B M58-0293-2 Figure 5–27. Vibration Trend Polar Chart