What was found
(CAN) DURING CRUISE AT FL 410, CREW NOTED INCREASED NOISE LEVEL AND CABIN ALT RISING. LOUD BANG FOLLOWED WITH DECOMPRESSION OF CABIN. SECONDARY DOOR SEAL HELD AGAINST TOTAL DECOMPRESSION. EMER DESCENT AND UNSCHEDULED LANDING FOLLOWED. ON GROUND IT WAS FOUND THAT CONSIDERABLE WATER WAS PRESENT IN DOOR SEAL AREA, BOTTOM PORTION. A/C WAS IN HOT AND HUMID ENVIRONMENT, WHICH CAUSED VISABLE SIGNS OF CONDENSATION BOTH INSIDE AND EXTERNALLY. A/C THEN MADE STOP WERE HEAVY RAINS WERE ENCOUNTERED. ONCE IN CRUISE HEADING NORTH, OAT WAS APPROX -50 DEGREES, APPEARS TO HAVE FROZEN ACCUMULATED WATER, WHICH CAUSED A PARTIAL OPENING OF PRIMARY SEAL. DOOR SEAL AND FEED LINE WAS DRIED OUT. A/C RETURNED TO SERVICE.