The present invention provides a system and method for using the external accelerometer
in an aircraft engine configuration as a backup accelerometer, in the event the
internally located production accelerometer fails. The sensor location of the external
accelerometer has an acceptable sensitivity to fan imbalance, similar to the location
of the former alternate accelerometer. The signal from this external accelerometer
is duplicated using software in the signal conditioning hardware, creating the
second, alternate signal. As an alternative embodiment, the signal may be duplicated
by simply teeing or branching the original signal, using hardware rather than software.
