NOTE: The time to make the temperature stable can be decreased
____ to a minimum of 3 minutes if the engine was operated less than 15 minutes before this procedure. This 3 minute time is not necessary if the trim balance procedure is started less than 5 minutes after the engine was operated at high power and was not stopped.
(h)
Do the analyzer auto-test.
(i)
Set the analyzer for a TRF sensitivity of 50 pC/g.
(j)
Set the analyzer to the configuration that will measure the data correctly.
(k)
Set the analyzer to the engine on test.
(l)
Put into the analyzer, 856A2636G01, the weight and location of the initial balance screws that are installed radially in the spinner cone.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
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737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
(m)
Increase the speed of the engine slowly to the correct takeoff target %N1.
(n)
Decrease the speed slowly and continuously until the engine is stable at the N1 speeds shown in Figure 504. 1) Monitor the FAN and TRF vibrations during the deceleration. 2) Make sure the vibrations become stable. 3) If the vibration levels are more than 8.0 mils DA, do these
steps: a) Decrease the speed until the vibration amplitudes are equal to or less than 8.0 mils DA. b) Do the balance procedure with the speeds available with the vibration amplitudes lower than 8.0 mils DA.
(o)
When the vibrations become stable, put into the analyzer the
vibration amplitude (U) and phase angle (A) for each sensor,
the front and the rear.
NOTE: If the vibration does not become stable in 1 minute,
____ continue the procedure, but do not keep this data.
NOTE: A minimum of 3 different speeds are necessary to do a
____
simultaneous 2-plane computation.
S 825-008-C00
(2) Use the analyzer to decrease the vibrations as follows.
(a)
Decrease the speed to minimum power.
(b)
After 5 minutes, when the engine becomes stable, do the engine shutdown procedure (AMM 71-00-00/201).
(c)
With the analyzer, calculate the balance weight and the
location of the balance screws.
(d)
Do the selection of the balance screws as follows:
1) Get the part number(s) of balance screw(s) from Fig. 508 if the location center is on a screw hole, or Fig. 509 if it is between two screw holes.
NOTE: The analyzer will show if the the center of the
____ location is on or between the screw holes.
2) Write the selection of balance screw(s) and locations(s) on a balance screw location chart (Fig. 502).
(e) Install the new balance screws as follows:
CAUTION: MAKE SURE THAT YOU PUT COVERS ON ALL OF THE LOWER
_______ HALF OF THE INLET COWL SURFACE. ALSO MAKE SURE THAT THE EDGES OF THE MATS TOUCH OR ARE ATTACHED WITH SOME TAPE. IF THE EDGES ARE NOT, THEN THE TOOLS OR PARTS CAN FALL AND CAUSE DAMAGE TO THE INLET COWL SURFACE.
1) Put the protective mats, with tape along the adjacent edges, on the inner lower half of the inlet cowl.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
2) Replace the initial balance screws with the new,
lubricated, balance screws that you got.
NOTE: All the initial balance screws must be replaced by
____ new balance screws or P07 screws, if it is necessary.
The torque value for the balancing screws is 70-75 pound-inches (8.0-8.5 Newton meters).
3) Remove the protective mats and all other remaining unwanted material from the inlet cowl.
(f)
Put into the analyzer the new weight and location of the balance screws that are installed in the spinner cone.
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