What was found
THE ELBOW FITTING BETWEEN THE SHUTOFF VALVE & PULSE VALVE WAS PUSHED OUT OF THE LINE ON ALL THREE HUMIDIFIER SYSTEMS. THIS APPEARS TO HAVE BEEN CAUSED BY WATER FREEZING IN THE LINES (THE AIRCRAFT WAS STOP IN POLAND DURING 3 DAYS WITH VERY NEGATIVE TEMPERATURES), RESULTING IN WATER BEING INJECTED DIRECTLY INTO THE AIRCRAFT AIR SY. WATER WAS OBSERVED COMING OUT OF THE AIRCRAFT VENTS & CEILING PANELS DURING SYSTEM OPS, DESPITE NO SYSTEM FAULTS BEING INDICATED. WATER COMING FROM ACFT VENTS & CEILING PANELS COULD CAUSE SHORT-CIRCUITING OF ELECTRIC EQUIPMENT; ROOT CAUSE IS UNCLEAR AT THIS TIME. UNKNOWN IF OTHER ACFT (LIST INTRODUCED WITH ISSUE B OF THIS REPORT) LISTED ABOVE ARE AFFECTED OR NOT.