As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PRIOR TO THE SECOND FLIGHT OF THE DAY THE PILOT NOTICED HYDRAULIC FLUID ON THE SIDE OF THE FUSELAGE. FURTHER INSPECTION REVEALED LEAK ORIGINATED FROM THE HYDRAULIC COMPACT UNIT. THE O-RING ON THE FILTER SHROUD HAD FAILED. O-RING REPLACED. AIRCRAFT GROUND RUN FOR LEAK CHECK AND RETURNED TO SERVICE. (TC NR 20051208004)