What was found
AT FL 350 LOST CABIN PRESSURE, COULD NOT CONTROL IN ANY MODE. EXECUTED EMERGENCY DESCENT & MANUALLY DEPLOYED MASKS, DECLARED EMERGENCY. MX PERFORMED TEST OF OUTFLOW VALVE & FOUND HEATER GASKET INOP. R / R OUTFLOW VALVE, CABIN PRESS CONTROLLER AND CABIN PRESSURE CONTROL PANEL. CONFIRMED FAILURE OF CABIN PRESS CONTROL PANEL FINDING SWITCH DEFECTIVE, A BROKEN SWITCH SHAFT, CAPACITORS LEAKING, & OBSOLETE DRIVE BELTS. REPLACED DEFECTIVE PARTS, OVERHAULED UNIT IAW CMM. INCOMING TEST OF CABIN PRESS CONTROLLER CONFIRMED REASON FOR REMOVAL, UNIT FOUND TO HAVE A TRANSDUCER OUT OF TRIM. ALIGNED UNIT TO OEM SPECS, & PERFORMED CHECK OF OUTFLOW VALVE COULD NOT CONFIRM REASON FOR REMOVAL, UNIT PASSED ALL INCOMING TESTS.