As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE NR 2 HYDRAULIC SYSTEM LOST QUANTITY AND PRESSURE SHORTLY AFTER TAKEOFF FROM IAH. FUEL WAS DUMPED AND THE AIRCRAFT WAS RETURNED TO IAH WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE NR 2 HYDRAULIC SYSTEM HYDRAULIC SHUTOFF VALVE IN TAIL FAILED. THE SHUTOFF VALVE WAS REMOVED AND REPLACED AND LEAK AND OPERATIONAL CHECKS WERE GOOD.