What was found
(CAN) DURING FLIGHT AT FL 350,CREW HEARD A LOUD NOISE AND CABIN CLIMBED TO 20000FT/MIN. IMMEDIATELY CREW PRCEEDED EMERGENCY DECENT IAW QRH TO FL100. CREW ALSO NOTICED THAT NO FRESH AIR WAS NOTICEABLE EVEN AFTER RAM AIR SWITCH WAS TURNED ON. MAINT FOUND COCKPIT AIR SUPPLY CONTROL VALVE AT PRESSURE BULKHEAD WITH ONE FLAPPER MISSING. THE OTHER FLAPPER WAS DEFORMED. ALSO THE AIR SUPPLY DUCT DIRECTLY BEHIND THE BULKHEAD HAS THE AFT UPPPER END BROKEN OFF THE DUCT, LEAVING THE DUCT OPEN TO THE ENVIRONMENT IN THE UNPRESSURIZED SECTION OF THE AIRCRAFT.