What was found
AIRCRAFT WAS GROUNDED. CABIN ODOR REPORTED ON DESCENT WHEN ENGINES AT IDLE, SEEMED TO DISSIPATE WHEN ENGINES WERE ABOVE IDLE. FLIGHT CREW REPORTED WHEN GETTING ON A/C IN RSW THE COCKPIT SMELT LIKE THE DIRTY SOCK SMELL. DURING FLIGHT, NO ISSUES BUT ON DESCENT INTO CLT AS ENGINES WENT TO IDLE THE FLIGHT CREW REPORTED A STRONG DIRTY SOCK SMELL SO BAD THAT THE C/O PUT ON HIS MASK. UPON LANDING SMELL WAS GONE. ACCOMPLISHED CABIN ODOR TROUBLESHOOTING DECONTAMINATION FOUND APU GENERATOR LEAKING OIL. REPLACED GENERATOR PER AMM 24-32-51, NO FURTHER EVIDENCE OF ODOR OK FOR CONTINUED SERVICE.