As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE, FLIGHT CREW REPORTED -Y- HYDRAULIC SYSTEM LEVEL LOW. AS A PRECAUTIONARY MEASURE, AN EMERGENCY WAS DECLARED UPON LANDING AT PDX. REPLACED NR 2 ENGINE YELLOW SYSTEM CASE DRAIN RETURN LINE FOR LEAKING. RAN NR 2 ENGINE. OPS AND LEAK CHECKED NORMAL. NO LEAKS NOTED. REF AMM 29-13-49-000-008 AND 29-13-49-400-008.