As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE, OBSERVED HYDRAULIC SYSTEM 1 REDUCTION IN QUANTITY .1 GALLON IN 6 MINUTES AND INCREASED TO .1 GALLON IN 4 MINUTES. RETURNED TO DEPARTURE. REMOVED AND REPLACED THE HYDRAULIC SYSTEM 1 QUANTITY TRANSMITTER IAW AMM 29-32-02. HYDRAULIC INDICATION SYSTEM CHECKED SATISFACTORY.