As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
5 MINUTES AFTER TAKEOFF, 500 FT AGL CRUISE 80 KIAS, HYDRAULIC WARNING LIGHT ILLUMINATED, HORN SOUNDED AND CONTROLS STIFFENED. ISOLATED AND RETURNED TO TAKEOFF POINT, MADE EMERGENCY LANDING WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED THE HYDRAULIC DRIVE BELT.