(a)  Find out if the weight location is centered on one screw hole
 or is between two screw holes.
 (b)  Get the new balance screws (Figs. 508 and 509).
 (c)  Make a record of the new balancing screws and their locations
 on a balancing screw location chart (Fig. 502).
 (d)  Remove the weights that were installed for the vectorial
 analysis engine run.
 (e)  Install the new screws which are written on Fig. 502.
 NOTE:____ The torque value for the balancing screws is
 70-75 pound-inches (8.0-8.5 Newton meters).

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(f)  
Do a last engine run to do a check for the remaining imbalance with the one-shot plot procedure. 1) Make a record of the U4 values and A4 values.

 (g)  
If the vibration amplitudes are not more than the limits, the trim balance procedure is completed. 1) Do this subsequent task: Put the Airplane Back to Its

 Usual Condition.

 (h)  
If the imbalance continues to be more than the limits, do troubleshooting, as follows, of the vibration indicating system to make sure the indications are correct: 1) Examine all of the data from engine runs to make sure you

_____________ calculated the results correctly.
________________________________
 2)  Make sure the instruments were set and calibrated with the correct values.
 3)  Examine the condition of all connectors.
 NOTE: Dirty or wet connectors can cause incorrect
____
 vibration indications.

 4)  Do a check for accelerometer mounting brackets that are
 loose.

 5)  Make sure all of the leads are satisfactorily attached (with clamps, tape, or other fasters) at locations that are not less than 6 inches (15 cm) apart.
 NOTE: Leads that are free to move or shake can cause
____
 incorrect vibration signals.

 6)  Install the initial balance screws again from Fig. 502.
 NOTE: The torque value for the balancing screws is
____ 70-75 pound-inches (8.0-8.5 Newton meters).
 7)  Do a second initial engine run.
______
 8) Compare the amplitude and phase angle indications of the
 second initial engine run with the results of the first

______ _____ initial engine run.
 9)  Do the one-shot procedure with the data from the second
______ inital engine run. 10) Compare the calculated balance weight and angle with balance weight and angle that you calculated from the first
_____ initial engine run (W1 at A1).
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11) If the W1 and A1 values of the two engine runs are almost the same, the equipment was installed correctly during the first engine run. a) Do this subsequent task: Put the Airplane Back to Its
 Usual Condition.
 NOTE: The last weight configuration that was
____ calculated (WO4 at AO4, which is more than the limits) is correct. Thus, it is not possible to correct the vibration problem sufficiently without the removal of the engine.
 12) If the W1 and A1 values of the two engine runs are too different, it is possible that the equipment was incorrectly installed for the first engine run. a) If the imbalances from the second initial engine run
______ are lower than those from the first initial engine run,
_____ do as follows.
 1. Use the values from the second initial engine run
_ to do the procedure again.
 (i)  If the analyzer procedure decreased the Fan vibration levels as follows, do the Two-Plane Trim Balance Procedure. 1) The vibration levels of the No. 1 bearing (or FFCCV) were
 decreased to not more than 3.5 mils DA. 2) The vibration levels of the TRF were not decreased to less
　
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