As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING APPROACH PHASE WHEN ATTEMPTING TO EXTEND THE LANDING GEAR, THE GEAR FAILED TO FULLY EXTEND WITH THE ENGINE DRIVEN PUMPS. PILOT SUCCESSFULLY EXTENDED GEAR USING THE EMERGENCY EXTENSION HANDLE. AFTER LANDING POST FLIGHT REVEALED SIGNIFICANT AMOUNT OF HYDRAULIC FLUID PRESENT ON LEFT LOWER NACELLE AFT. SOURCE OF HYDRAULIC FLUID WAS FOUND TO BE FROM THE LEFT ENGINE HYDRAULIC FILTER HOUSING. VISUAL INSPECTION OF THE FILTER HOUSING REVEALED A RADIAL CRACK AROUND THE THREADS HOLDING THE HOUSING TO THE FILTER BASE.