Boeing 767 - Subtask 72-31-00-975-054-G00; Subtask 72-31-00-975-055-G00; Subtask 72-31-00-975-056-G00; Subtask 72-31-00-975-057-G00

SUBTASK 72-31-00-975-054-G00
(2) Measure and make a record of the angle (X) from the 0° radial line to R1.
(a) Make a record of the clockwise direction from the 0 degree radial line to R1.
SUBTASK 72-31-00-975-055-G00
(3) Calculate the weight (WF) needed to balance the engine as follows: WF = Wt X (Uo/R1)
SUBTASK 72-31-00-975-056-G00
(4) Select the balance screws for WF from the Table of Balance Screw Weights (Figure 505).
SUBTASK 72-31-00-975-057-G00
(5) Calculate the spinner hole location to install the balance screw or screws as follows:
(a) Angle (X) divided by 9.5 = location for WF
SUBTASK 72-31-00-435-058-G00
(6) Do the steps that follow to install the balance screws (Figure 506):
(a) Put protective mats on the bottom half of the internal inlet cowl.
(b) Remove the balance screw or screws to be replaced.
1) Make a record of the location of each of the screws that you remove.
(c) Keep the balance screws because it is possible you will have to put them back in the
same location.
(d) Install the replacement balance screws.
1) Tighten the screws to 50-75 pound-inches (5.6-8.4 newton meters).
SUBTASK 72-31-00-945-031-G00
(7) Remove the protective mats from the internal inlet cowl.
K. Do a check of the correction for the imbalance of the engine.
SUBTASK 72-31-00-865-059-G00
(1) Do the steps in the Operate the Engine paragraph.
NOTE: Operate the engine at the same N1 speed (rpm) that was used for the initial engine
run.
(a) Look at the engine vibration indication on the lower EICAS display.
1) The guideline is 2.5 units (on the display). No sudden changes of 1.0 units or more
are allowed (PAGEBLOCK 71-00-00/201).
2) If the vibration amplitude is less than the guideline, the trim balance procedure is
complete.
3) If this procedure cannot balance the engine, do the Low Pressure Turbine (LPT)
Trim Balance Procedure (PAGEBLOCK 72-52-00/501).
END OF TASK
767
AIRCRAFT MAINTENANCE MANUAL
CF6-80A SERIES ENGINES
72-31-00
NoC
Page 524
D633T1B7 Aug 22/2017
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
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