As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT START OF DESCENT, HEAVY SMOKE FILLED THE CABIN AND COCKPIT. SUPPLEMENTAL DATA UPDATE: THE APU HAD A SEVERE COOLING FAN FAILURE WHICH CAUSED OIL TO LEAK IN THE INLET PLENUM, CONTAMINATING THE AIR CONDITIONING SYSTEM. THE COOLING FAN HAD THE SHROUDED ROTOR. PART TOTAL CYCLES, 2,347.