As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EMERGENCY DECLARED, C HYD SYSTEM LOSS OF FLUID. DID NOT HAVE TO USE EMERGENCY SYSTEMS FOR LANDING. REPLACED AN O-RING TO THE ADP FILTER MODULE CENTER DPI. LEAK CHECKED GOOD SERVICED AND CYCLED CONTROLS. OPS OK FOR SERVICE AMM 29-11-19.