What was found
THE AIRCRAFT NR 1 VERTICAL GYRO WAS INOPERATIVE, ON CLIMBOUT OF BAHRAIN N2 (FIRST OFFICER) FAILED, THE CREW UNABLE TO RESET OR RESTORE IT AND DECIDED TO RETURN BACK TO BAHRAIN. AT BAHRAIN MAINTENANCE REPLACED THE F/O ATTITUDE DIRECTOR INDICATOR PER MM 34-23-02 OP'S CHECK GOOD, AIRCRAFT RETURN TO SERVICE.