As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 2353 - EN ROUTE ORD-JAC, SHORTLY AFTER TAKEOFF DETECTED HYDRAULIC QUANTITY QUICKLY DROP TO ZERO. RETURNED ORD AND LANDED WITHOUT FURTHER INCIDENT. REPLACED NR 1 ENGINE HYDRAULIC PUMP. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)