As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING COLLECTOR TANK CHECK VALVE FUNCTIONAL TEST, THE RIGHT CHECK VALVE WAS FOUND TO BE LEAKING. DURING INVESTIGATION, THE CHECK VALVE FITTING WAS FOUND TO HAVE A MANUFACTURING DEFECT, NOT ALLOWING THE CHECK VALVE TO SEAT PROPERLY. THE FITTINGS CHECK VALVE MATING SURFACE HAS A RISE, WITH A SMALL CRACK NEXT TO IT. THE CHECK VALVE FITTING WAS REPLACED.