What was found
(CAN) CREW OBSERVED CABIN ALT FLUCTUATION (BOTH INCREASING AND DECREASING) WITH CAB RATE OF CLIMB 2000 FPM. THE AIRCRAFT DESCEND TO A/C ALT 7000 FT (WITH CAB ALT 6000 FT). AIR TURN BACK PERFORMED. CREW REPORTED EAR ACHE AND A KIND OF WHITE SMOKE MOMENTARILY. MAINTENANCE TESTED THE NORMAL OUTFLOW VALVE PER AMM TASK 21-30-11-720-801. GENERAL CONDITION CHECK WAS CARRIED OUT FOR RELATIVE COMPONENT BUT NO FAILURE WAS CONFIRMED. FOLLOWING COMPONENTS WERE REPLACED: NORMAL OUTFLOW VALVE, CABIN PRESSURE CONTROLLER AND CABIN PRESSURE SELECTOR PANEL. AIRCRAFT IS BACK INTO SERVICE WITHOUT ANY FURTHER REPORTED ISSUE. (TC# 20190610009)