What was found
DURING CRUISE, HEARD A LOUD POP, FOLLOWED BY RAPID DECOMPRESSION OF CABIN. R & R OUTFLOW VALVE ACTUATOR, IAW AMM, OPS CHECKED GOOD. R & R CABIN PRESSURE SELECTOR IAW AMM FOUND NR1 CABIN PRESSURE CONTROLLER FAILED BITE TEST. SWAPPED NR1 & NR2 PRESSURE CONTROLLERS PROBLEM FOLLOWED. R & R NR 2 PRESSURE CONTROLLER IAW AMM. PRESSURIZED CABIN TO VERIFY INTERGITY AND FOUND NO LEAKS IAW AMM.