As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE COMING FROM APU TAILPIPE ON SHUTDOWN. MAINTENANCE FOUND APU OIL LEVEL LOW AND OIL IN TAIL PIPE. MAINTENANCE FOUND THE OIL LEAK FROM STARTER PAD DUE TO A MISSING O-RING ON THE STARTER WHICH RESULTED IN THE REPLACEMENT OF THE STARTER IAW AMM 49-42-51. A SATISFACTORY OPS CHECK WAS ACCOMPLISHED. IAW AALA 201607119004 WHICH REPLACED THE APU.