What was found
AT FL 310 AND IN NORMAL CRUISE, PRESSURE FLOW LIGHT BEGAN TO FLICKER, FOLLOWED BY CABIN CLIMBING 500-600FT. OUTFLOW VALVE WAS MANUALLY CLOSED AND CABIN CLIMBED TO 7300, FLOW LIGHT CONTINUED TO FLICKER CABIN DIFFERENTAL PRESSURE ROSE TO 8.0 PSI AND STAYED THERE UNTILL APPROX 15,000 IN THE DECENT. CABIN ALSO STAYED 4000 FT UNTILL 15,000 CONTROLLER IN AUTO.