As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 302 PHX-CLT - RETURN TO FIELD / EMERGENCY LANDING - BLUE SYSTEM LOSS & LOW LEVEL WARNING. CREW DECLARED AN EMERGENCY, RETURNED TO PHX AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND BLUE RESERVOIR DRAIN VALVE LEAKING. REPLACED DRAIN VALVE 2264GM IAW MM 29-12-35-401.