TM 55-2840-254-23
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1-107 TEST ENGINE (AVIM) (Continued)
f. Adjust channel gain potentiometer (small setscrew immediately above CHANNEL SELECTO R) for
channel 1 to obtain a full scale deflection indication.
g. Repeat steps b. through e. for remaining channels 2 and 3.
If check after testing discloses that adjustment of meter has changed more than 1/16 inch higher than the
full scale readings, it must be assumed that some of the meter indications recorded during test were inaccu-
rate, In this case, the entire vibration test must be conducted again. If defective transducers are suspected
of producing incorrect meter indications, replace transducers and check their operation with a trial vibra-
tion test, conducted at only one combination of N1 and N2 speeds. If comparison with recorded indica-
tions on engine test log discloses a defective transducer, the entire test must be conducted again with
transducers known to be good.
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