What was found
PILOT REPORTED AFTER DEPARTURE FROM MAZ & DURING TRANSITION FROM CLIMB TO CRUISE SMOKE & FUMES WERE DETECTED COMING FROM DEFROST VENT. PILOT CLOSED DEFROST, RAM AIR & CABIN AIR VENT VLVS. UPON CLOSING CABIN VENTILATION VLVS, PILOT REPORTS SMOKE & FUMES NO LONGER ENTERING CABIN. PILOT RETURNED TO MAZ AS A PRECAUTION. COMPANY MX INSPECTED ACFT & FOUND HYD RESERVOIR SIGHT TUBE SPLIT & ALLOWING HYD FLUID TO ATOMIZE WHILE UNDER PRESS. COMPANY MX REPLACED HYD RESERVOIR SIGHT TUBE, SERVICED HYD RESERVOIR & PERFORMED OPERATIONAL & LEAK CHECKS PRIOR TO RELEASE.