As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DUE TO FUMES IN CABIN, DECLARED AN EMERGENCY AND RETURNED TO DEPARTURE. MAINTENANCE FOUND HYDRAULIC FLUID LEAKING DUE TO A CRACKED HYDRAULIC LINE AT CHECK VALVE 2595GM AND REPAIRED IT PER AMM TASK 20-31-11-300-009-A. AIRCRAFT WAS GROUNDED.