As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
VERY STRONG DIRTY SOCK/MUSTY ODOR AFTER APU TURNED ON AND PACKS TURNED ON. A/C WAS ON EXT AIR W/ APU OFF WHEN WE ARRIVED. ODOR STARTED AFTER APU TURNED ON. PERFORMED GVI OF APU INLET. FOUND PUDDLE OF DEICE FLUID UNDER BULKHEAD DRAIN AND APU INLET CLEANED. PERFROMED LEVEL A AND B DECONTAMINATION OF ECS. NO ODORS PRESENT. (8124434).