What was found
DURING CLIMBOUT PASSING FL 330 FLOW LIGHT ILLUMINATED WITH RAPID RISE IN CABIN PRESSURE. SWITCHED AUTO CONTROLLER BUT COULD NOT ARREST PRESSURE LOSS. ACCOMPLISHED RAPID DEPRESSURIZATION CHECKLIST AND DID EMERGENCY DESCENT. MANUAL PRESSURIZATION CONTROL JAMMED, UNABLE TO CONTROL PRESSURE. DESCENDED TO 10,000. EMERGENCY DECLARED. AND RETURNED TO DEPARTURE. AIRCRAFT WAS GROUNDED. PERFORMED INSPECTION OF AFT ACCESSORY COMPARTMENT FOR LOOSE A/C DUCTS. NO DISCREPANCIES FOUND. PERFORMED TEST OF FUSELAGE LEAKAGE AND LEAK RATE PASSED IAW AMM 21-00-00-5-0 PARA 4H. PERFORMED BITE TEST OF NR 1 AND 2 CABIN PRESSURE CONTROLLERS WITH NO FAULTS FOUND IAW AMM 21-32-00 CONFIG 5 PARA 3B. PERFORMED TEST OF PRESSURIZATION CONTROL WHEEL AUTO/ MANUAL SWITCH S1-54 AND TESTED GOOD IAW AMM 21-32-05-0 PARA 3C. VERIFIED CONTROL WHEEL MOVED SMOOTHLY AND WITHOUT BINDING IN MANUAL MODE IAW AMM 21-32-02-5 PARA 3C STEP 11. INSPECTED CABIN OUTFLOW VALVE AND BUTTERFLY ASSYS WITH NO DEFECTS FOUND IAW AMM 21-32-05-6 CONFIG D. REMOVED AND REPLACED CABIN OUTFLOW VALVE ACTUATOR.