As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER APU START "DIRTY SOCK SMELL WAS PRESENT IN CABIN AND COCKPIT, WENT AWAY AFTER ENGINE START. ON LANDING SAN SAME SMELL WAS AGAIN PRESENT. DUE TO RECENT HISTORY ENGINEERING REQUESTS APU BE REPLACED. OIL FOUND AT APU BLEED AIR VALVE CONFIRMING APU AS THE SOURCE. REPLACED APU. OPS/LEAK CHECKED APU. REF T/C 78349010.