FAN AND LOW PRESSURE COMPRESSOR SECTION - ADJUSTMENT/TEST
1. General
A. There are two trim balance procedures.
(1) The first procedure uses a trim balance analyzer to measure the amplitude and phase angle of
the engine vibration and the N1 speed.
This data is used to calculate the balance correction weight to be installed in the spinner cone.
(2) The second procedure does not use a trim balance analyzer. The procedure uses the vibration
signal that is shown in the flight compartment to find the balance correction weight.
TASK 72-31-00-705-035-G00
2. Trim Balance Procedure - (Uses a Trim Balance Analyzer)
A. General
(1) In this procedure a trim balance analyzer is used to measure the vibration amplitude (U), the
phase angle (A), and the N1 speed of the engine at the time the data was taken. With this
data, a trim balance matrix is used to find the balance correction weight and the spinner hole
location to install the balance weight. Balance screws are then installed in the spinner cone.
(2) The terms and symbols used in this procedure are specified as follows:
(a) Vibration Amplitude (U) - The engine imbalance as measured by the No. 1 bearing
accelerometer and shown on the trim balance analyzer, in units of mils.
(b) Phase angle (A) - The phase angle of the engine imbalance as shown on the trim
balance analyzer in units of degrees.
(c) Weight (W1, W2, W3, etc.) - A balance correction weight in grams. It is a balance screw
(or screws) which are installed on the spinner cone.
(d) R - The resultant imbalance (in units of mils) because of the correction weight (W). R1 is
the resultant imbalance because of W1. R2 is the resultant imbalance because of W2.
B. References
Reference Title
71-00-00 P/B 201 POWER PLANT (OPERATING PROCEDURES) -
MAINTENANCE PRACTICES
71-11-04 P/B 201 FAN COWL PANELS - MAINTENANCE PRACTICES
(OPEN/CLOSE)
71-11-06 P/B 201 CORE COWL PANELS - MAINTENANCE PRACTICES
(OPENING/CLOSING)
72-52-00 P/B 501 LOW PRESSURE TURBINE (LPT) SECTION -
ADJUSTMENT/TEST
78-31-00 P/B 201 THRUST REVERSER SYSTEM - MAINTENANCE PRACTICES
C. Tools/Equipment
NOTE: When more than one tool part number is listed under the same "Reference" number, the
tools shown are alternates to each other within the same airplane series. Tool part numbers
that are replaced or non-procurable are preceded by "Opt:", which stands for Optional.
Reference Description
COM-3932 System - Portable Engine Balancing
767-200
Part #: PBS-4100 Supplier: 26741
767
AIRCRAFT MAINTENANCE MANUAL
CF6-80A SERIES ENGINES
72-31-00
NoC
Page 501
D633T1B7 Dec 22/2016
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
EFFECTIVITY
ABX 001-007, 011, 012, 016-019, 021, 022, 025, 101,
109, 114, 115, 314-999
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