As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 778, LAS-BOS, AIR RETURN BACK TO LAS. FLIGHT CREW RECEIVED THE FOLLOWING MESSAGE ON ECAM, HYD G ENG 1 PUMP LO PR AND HYD G SYS LO PR. CREW ELECTED TO PERFORM AIR TURNBACK. R & R MLG BYPASS VALVE IAW AMM 32-31-13. PERFORMED OPS CHECK AND LEAK CHECK. OPS CHECK AND LEAK CHECK PASSED. SERVICED GREEN HYDRAULICS SYSTEM IAW 12-12-29.