As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: CREW DECLARED AN EMERGENCY INTO PHL ACCOUNT YELLOW HYDRAULICS LOW QUANTITY INDICATION. FLIGHT LANDED WITHOUT INCIDENT AND TAXIED TO THE GATE. FOUND YELLOW HYDRAULIC SYSTEM POWER TRANSFER UNIT MANIFOLD LEAKING AND REPLACED IT PER AMM 29-13-15-400-001A. HYDRAULIC SYSTEM WAS SERVICED TO FULL AND A SATISFACTORY LEAK AND OPERATIONAL CHECK WAS ACCOMPLISHED PER AMM 29-12-00 AND 29-10-210-002A.