As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT AT CRUISE AT 43,000'. CONDITIONED AIR DUCT CAME LOOSE FROM WATER SEPARATOR, CABIN BEGAN DEPRESSURIZING. CHECK VALVE LOCATED ON AFT PRESSURE BULKHEAD FAILED WHEN IT CLOSED BREAKING APART INTO CONDITIONED AIR DUCT LINE. AIRCRAFT BUILT IN 1980. HINGED DOORS ON CHECK VALVE ARE FABRICATED OUT OF PLASTIC. PLASTIC DOORS ON CHECK VALVE BECAME BRITTLE DUE TO ITS WORKING ENVIRONMENT AND TIME IN SERVICE. CHECK VALVE IS AN ON CONDITION PART, NO LIFE LIMIT. INSPECTION BY BOROSCOPE AT 1200 HOURS OR 3 YEAR INTERVALS.