What was found
AT CRUISE FL 210 RECEIVED A CABIN PRESSURE WARNING. PERFORMED A EMERGENCY DESCENT TO 10,000 AND RETURNED TO FIELD. LANDING UNEVENTFUL. FOUND CPC/OF VALVE DATA FAIL AND CP CONTROLER FAIL IN CDS, C/W FIM 21-3000-810-804 1-3 & 5 VALVE FAIL MESSAGE DID NOT RETURN, C/W FIM 21-30-00-810-809 1-3 AND 4B-5, REPLACED CP CONTROLER IAW 21-31-06-000-801, 21-31-06-400-801 OP CK, FUNCTIONAL TEST GOOD. RETURNED TO SERVICE.