As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FIGHT, PILOT REPORTED SMOKE IN THE COCKPIT AND RETURNED TO AIRPORT FOR AN UNEVENTFUL LANDING. THE MAINTENANCE DEPARTMENT WAS DISPATCHED. POSSIBLE CAUSE WAS HYDRAULIC MANIFOLD SOLENOID STUCK AND CAUSED SYSTEM TO OVERHEAT CAUSING A PIN HOLE IN THE HYDRAULIC SIGHT GAUGE. THIS CAUSED THE HYDRAULIC FLUID TO ESCAPE AS A MIST.