As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 977 CLT-PDX - RETURN TO FIELD - CREW REPORTED LOSS OF YELLOW HYDRAULIC SYSTEM. AIRCRAFT RETURNED TO CLT AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED O-RING ON BRAKE AUTOMATIC SELECTOR 2576GM. SERVICED SYSTEM AND OPERATED WITH NO LEAKS NOTED.