As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT THE ISIS ATTITUDE INDICATOR TUMBLED IN FLIGHT. THE ACFT RETURNED TO FIELD & LANDED WITHOUT INCIDENT. DEFERRED THE ISIS, THE DEFERRAL WAS CLEARED THAT EVENING BEFORE THE ACFT RESUMED FLIGHT BY REPLACING THE ISIS. OPERATIONAL CHECKS WERE GOOD WITH NO FURTHER DEFECTS NOTED.