As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 1842 - EN ROUTE ORD-IAD, NR 2 HYDRAULIC SYSTEM PRESSURE DECREASED TO ZERO. RETURNED ORD AND LANDED WITHOUT FURTHER INCIDENT. REPLACED NR 1 AND NR 2 HYDRAULIC PUMPS AND FILTERS. RAN BOTH ENGINES. NO LEAKS NOTED. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)