As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: ON DECENT WITH IDLE POWER AND APU OFF, SMELL IN CABIN AND FLIGHT DECK OF WET SOCKS. APPROPRIATELY 15000FT ALTITUDE WITH VMC CONDITIONS/NO MOISTURE. SWITCHING AIR SOURCE FROM ENGINE TO APU HELPED.TURNING OFF PACK 1 HELPED A LOT. SMELL WENT AWAY ONCE AIRPLANE APPLIED POWER. MAINTENANCE FOUND THE APU SURGE CONTROL VALVE LEAKING FUEL AND REPLACED IT. A SATISAFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO ISSUES NOTED.