FAU-39 is an electronic device which can be installed in the center of gravity of an aircraft to monitor the vertical acceleration of the aircraft.During the system operation, the FAU-39 unit records into its internal solid-state memory to following parameters:

Aircraft basic information (type, reg. makrs, S/N, etc…)
Number of flight hours
Number of landings
Aircraft vertical acceleration value, which exceeded predefined positive or negative limits of vertical acceleration as well as the time when event ocurred
Difference between two successive relative extreme values of vertical acceleration in form of Peak/Valley frequency matrix