While reviewing the logs of an '82 M20K I came across an entry showing the replacement of the original mechanical tachometer with a new EI electronic unit. While that's not unusual, the entry refers to the aircraft time shown on the "Maintenance Hrmtr (lower console)". Further in the entry it reveals "removed console hour meter". Since it's apparently gone now, I was curious about the reason Mooney may have put a specific clock for maintenance purposes versus simply using tach time, and if this clock is actually required equipment. Any gurus out there with knowledge on this?
