What was found
DIRTY SOCK ODOR IN THE MID CABIN AND AFT, AT GATE. PERFORMED A DETAILED INSPECTION OF THE APU COMPARTMENT AND THE APU PNEUMANTIC SYSTEM, NO INDICATION OF AN OIL LEAK WITHIN THE APU COMPARTMENT, NOR IN THE PNEUMATIC DUCT. CLEANED THE APU COMPARTMENT AND PERFORMED AN OPERATIONAL CHECK OF THE BLEED SYS IAW AMM 49-00-00-810-874 & 21-21-00. ACFT OK TO CONTINUE SERVICE.