What was found
WHILE DESCENDING BETWEEN 10000-8000FT A LOUD SOUND SIMILAR TO RUSHING AIR COULD BE HEARD FROM THE MAIN ENTRY DOOR. AT THE SAME TIME THE CABIN RATE DEPRESSURIZED AT A RATE OF 3200' DOWN UNTIL IT SETTLED AT A NORMAL RATE SHORTLY THEREAFTER (10SECS OR SO). THE FLIGHT WAS UNEVENTFUL UP TO THAT POINT. CORRECTIVE ACTION: REMOVED AND REPLACED PRESSURE VALVE DOOR SEAL. REMOVED PRESSURE VALVE DOOR PUSH ROD. INSTALLED NEW CONDITION PRESSURE VALVE DOOR PUSH ROD. ADJUSTED/RIGGED THE PRESSURE VALVE DOOR PUSH ROD LENGTH WITHIN LIMITS. PERFORMED MAIN CABIN DOOR OPS CHECKS. OPS AND FUNCTIONAL CHECKS GOOD WITH NO DEFECTS NOTED. REF: BOMBARDIER CL650 AMM 52-11-00 AND 51-21-13.