As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT THE GATE WITH EXTERNAL POWER SUPPLYING ELECTRICS & APU RUNNING THE PACKS, APU FAULT LIGHT ILLUMINATED & APU SHUTDOWN WITH SMOKE IN THE CABIN. LARGE PUDDLE OF OIL UNDER APU, APU OIL TANK SCUPPER ASSEMBLY DETACHED FROM OIL TANK. GND CREW REPORTS FLAMES FROM APU EXHAUST & GRINDING NOISES FROM APU. R & R APU IAW MCM 49-96-82.