As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAIL DURING START. RAMP AGENTS REPORTED SMOKE COMING FROM EXHAUST, BLOWING SMOKE FROM EXHAUST. STARTED APU WITH EXTERNAL POWER AND APU RAN NORMAL. DEPRESSED GEN SWITCHLIGHT AND UPON TURNING OFF OF EXTERNAL POWER, APU AUTOSHUTDOWN. R & R APU DC STARTER/GENERATOR IAW AM TASKS 24-33-01-000-801 + 24-33-01-400-801. ALSO, REPLACED GEARBOX OUTPUT SHAFT SEAL IAW AMM TASKS 49-90-17-000-801 AND 49-90-17-400-801, AND SERVICED APU WITH ENGINE OIL IAW AMM TASK 12-10-49-612-802. OPS CHECK OF APU AND STARTER/GENERATOR GOOD. NO LEAKS DETECTED. RETURNED TO SERVICE.