As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER APU START UP AND WARM UP AT THE GATE WHEN THE APU BLEED SELECTED ON THE DIRTY SOCK SMELL FILLED THE COCKPIT AND ENTIRE CABIN. SMELL WAS VERY STRONG. PERFORMED GVI OF APU COMPARTMENT. FOUND EVIDENCE OF AN OIL LEAK ON PLENUM. OK FOR SVC. (LP: 7403510)