What was found
AIRCRAFT WAS GROUNDED: AIRCRAFT RETURNED TO PHL. AFTER TAKE OFF CLIMBING TO 10K FEET. MANUAL LANDING ELEVATION ECAM ADVISORY WITH SWITCH IN AUTO. CABIN VERTICAL SPEED FLUCTUATING +400FPM TP -250FPM. FLIGHT ATTENDANTS HEARD WHISTLING NOISE REAR RIGHT SIDE OF AIRCRAFT. FLIGHT CREW STAYED BELOW 10K' AND RETURNED TO PHL WHERE THE AIRCRAFT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED #2 CABIN PRESSURE CONTROLLER 12HL PER AMM 21-31-34 AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.