What was found
WHILE CRUISING AT FL330, THE CABIN ALTITUDE CLIMBED TO 11,000 FT. CREW INITIATED AN EMERGENCY DESCENT TO 10,000 FEET AND DIVERTED TO BNA. CABIN STOPPED CLIMBING AND MAINTAINED 11,000 FEET UNTIL AIRCRAFT PASSED 15,000 FEET THEN CABIN STARTED DESCENDING AND OPERATED NORMALLY UNTIL JUST PRIOR TO LANDING. AFTER LANDING, THE CABIN PRESSURE AUTO FAIL LIGHT ILLUMINATED AND REMAINED ON UNTIL ENGINE WAS SHUT DOWN. LANDING AT BNA WAS UNEVENTFUL. MAINTENANCE FOUND THE LT DUCT OFF AND AFT END OF THE WATER SEPARATOR AND RESECURED IT. CHECKED SECURITY OF THE RIGHT DUCT. LEAK AND OPERATIONAL CHECK GOOD. AIRCRAFT RETURNED TO SERVICE. NO MENTION OF COM OR BITE IN LOGPAGE.