As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
"HYD 2 LO QTY" IN CRUISE FLIGHT. RESERVOIR SHOWED 12%, DROPPED TO ZERO OVER TIME. PSI REMAINED AT 3000 PSI FOR HYD SYSTEM 2. NO ABNORMALITIES WITH STEERING OR BRAKES NOTED ON LANDING. EMERGENCY DECLARED. REMOVED AND REPLACED NO 2. HYDRAULIC RESERVOIR IAW AMM 29-11-09. OP CHECK GOOD