As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FLIGHT ATTENDANTS REPORTED A BURNING SMELL IN THE BACK OF THE AIRCRAFT ON DESCENT. SPECIFICALLY A BURNING RUBBER SMELL. MAINTENANCE FOUND THE APU STARTER WAS LEAKING OIL AND REPLACED IT PER AMM 49-42-51. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED.