As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT AFTER TAKEOFF THE ISIS ATTITUDE INDICATOR WAS INOPERATIVE DURING FLIGHT. THE CREW RETURNED TO KORD AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE ISIS. OPERATIONAL CHECKS WERE GOOD WITH NO FURTHER DEFECTS NOTED.