As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. DFW, AIR INTERRUPT, ATL-LAX. EMERGENCY DECLARED. LANDING UNEVENTFUL. DURING CRUISE THE CREW OBSERVED THE YELLOW HYDRAULIC SYSTEM PRESSURE TO BE 0 WITH NO OTHER ABNORMAL INDICATIONS OR WARNING. QUANTITY SHOWED NORMAL. ACTIVATION OF YELLOW ELECTRICAL PUMP DID NOT PRODUCE A PRESSURE INDICATION. REMOVED AND REPLACED YELLOW SYSTEM PRESSURE TRANSDUCER IAW AMM 29-32-11. OPERATIONAL AND LEAK CHECK NORMAL.