As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) UPON NR 1 ENGINE START, AIRCREW OBSERVED "A SYSTEM" HYDRAULIC QTY DECREASING. MAINTENANCE VERIFIED HYD LEAK NEAR LT SIDE OF AFT AIRSTAIRS. FURTHER INVESTIGATION REVEALED THAT "A SYSTEM" MODULAR PACKAGE CHECK VALVE HAD FAILED AT THE VALVE`S THREADS. MODULAR PACKAGE REPLACED AND ACFT RETURNED TO SERVICE.