SUBTASK 72-52-00-975-028-G00
(2) Draw a vector to show the imbalance (U1) at phase angle (A1) from run number 2 with W1
installed.
SUBTASK 72-52-00-975-029-G00
(3) Draw a line that connects the vector tips, from Uo to U1. This line is R1.
SUBTASK 72-52-00-975-030-G00
(4) Measure and make a record of the length of R1 (in units of mils).
SUBTASK 72-52-00-975-031-G00
(5) Measure the angle from R1 to Uo. This is the correction angle (X). Make a record of the angle
and its clockwise direction from R1 to Uo.
NOTE: If you do not have a protractor, you can find the angle by transposition. Extend vector
Uo through the center of the polar plot. To transpose R1, draw a line parallel to R1
through the center of the plot. Find the angle (X) and the direction from R1 to Uo.
SUBTASK 72-52-00-975-032-G00
(6) Find the LPT center blade location by dividing the correction angle found in above step by 3.7°.
NOTE: 3.7 is used because 360° divided by 98 blades = 3.6735° between blades.
SUBTASK 72-52-00-975-033-G00
(7) Use the Table of Related LPT and Fan Blade Positions (Figure 505) to find the fan center blade
at the same angular position as the LPT center blade.
SUBTASK 72-52-00-975-034-G00
(8) Calculate (W2) as follows: W2 = W1 X (Uo/R1)
SUBTASK 72-52-00-975-035-G00
(9) Calculate the number of balance clips that are required.
NOTE: Each balance clip is equal to 95 gram-inches.
SUBTASK 72-52-00-975-036-G00
(10) Find the LPT blade locations to install the clips from the Balance Clip Distribution Table
(Figure 507).
NOTE: A maximum of seven clips can be installed on the low pressure turbine blades.
K. Install the W2 Balance Clips
SUBTASK 72-52-00-035-037-G00
(1) Do the steps that follow to remove the W1 balance clips:
WARNING
WEAR HEAVY GLOVES WHEN YOU MOVE OR TOUCH THE FAN
BLADES. THIS WILL PREVENT INJURY TO YOUR HANDS.
(a) Turn the fan blades so the fan center blade is at the six o'clock position.
1) The LPT center blade is now in the six o'clock position.
(b) Use a small screwdriver to carefully remove the aft tang of the clip from the blade.
(c) Use a needle-nose plier to carefully remove the balance clip.
(d) Discard the balance clip.
(e) Inspect the airfoil for damage (PAGEBLOCK 72-00-00/601).
767
AIRCRAFT MAINTENANCE MANUAL
CF6-80A SERIES ENGINES
72-52-00
NoC
Page 506
D633T1B7 Aug 22/2017
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
EFFECTIVITY
ABX 001-007, 011, 012, 016-019, 021, 022, 025, 101,
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