What was found
LEVEL 3 CABIN ALTITUDE WARNING DESCENDING THROUGH 35,000 FEET. CABIN ALTITUDE CLIMBED AS HIGH AS 13,500 FEET. COMPLIED WITH QRH AND PUT CABIN PRESSURE CONTROLLER IN MANUAL. CABIN PRESSURE WAS CONTROLLABLE IN MANUAL. REMOVED AND REPLACED CPC NR 1 IN REF TO AMM 21-31-04-2. NO FAULTS NOTED. AS PRECAUTIONARY PERFORMED VISUAL INSPECTION OF ALL CARGO DOOR SEALS AND PRESSURE RELIEF VALVES. NO DEFECTS NOTED. T/S PER FIM'S 21-33-01-00 AND 21-31-05-00. NO DEFECTS NOTED. ALL OPS CHECKS NORMAL.