As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE THE HYDRAULIC FLUID QUANTITY IN THE NR 4 SYSTEM INDICATED ZERO. AIRCRAFT CONTINUED TO DESTINATION, ALTERNATELY EXTENDED THE LANDING GEAR AND LANDED WITHOUT FURTHER INCIDENT. REPLACED THE NR 4 ENGINE DRIVEN HYDRAULIC PUMP. OPERATIONAL CHECK GOOD.