As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT DIVERTED. DURING CRUISE FLIGHT RECEIVED ECAM: HYD Y RESERVOIR LOW LEVEL QUANTITY INDICATED ZERO. INSPECTED AND FOUND RT SPOILER NR 4 SERVO CONTROL LEAKING. R & R RT NR 4 SPOILER SERVO CONTROL REF AMM 27-64-51, OPS CHECK AND LEAK CHECK GOOD. "Y" HYD SYSTEM WAS ACTUALLY AT 1.3 GAL, SERVICED TO WITHIN LIMITS. OK FOR SERVICE.