As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FLIGHT RETURNED TO PHL ON ACCOUNT OF HYDRAULIC LEAK. AFTER 2 HRS OF FLIGHT THE LEFT HYDRAULIC SYSTEM SHOWED .75 RF. WENT DOWN TO .73.. EMERGENCY DECLARED. MAINTENANCE FOUND LEAK AT VERT. STAB. HYDR. MANIFOLD. REPLACED 2 O RINGS. LEAK CHECK GOOD. SERVICED LT HYDR SYS AS REQUIRED.