As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 3331 - DURING CRUISE, CREW NOTED HYDRAULIC SYSTEM ONE QUANTITY IN THE YELLOW. PRESSURE WAS WITHIN LIMITS. CREW DIVERTED TO ORD, EMERGENCY WAS DECLARED AND AIRCRAFT WAS LANDED SAFELY. MAINTENANCE REMOVED AND REPLACED THE BRAKE SHUTTLE VALVE IAW EMB MM AND SERVICED THE NR 1 HYDRAULIC SYSTEM. OPS AND LEAK CHECKS WERE GOOD AND AIRCRAFT WAS RETURNED TO SERVICE. (M)