As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON GEAR RETRACTION AFTER DEPARTURE, CREW ADVISED THAT THE YELLOW HYDRAULIC SYSTEM RESERVOIR LEVEL WAS INDICATING LOW. FLIGHT RETURNED TO DEPARTURE, DECLARED AN EMERGENCY WITH ATC. FOUND YELLOW SYSTEM EDP PRESSURE LINE LEAKING. YELLOW SYSTEM EDP PRESSURE LINE REPLACED IAW AMM 29-13-49.