What was found
PASSENGER IN SEAT 4B & F/A NOTICED A BURNING RUBBER ODOR BETWEEN ROW 4 - 7 ON DESCENT. ODOR WAS NO LONGER PRESENT WHEN PASSENGER DISEMBARKED. NO SMOKE NOTED. CONFIRMED ODOR IS NO LONGER PRESENT. GROUND RAN ENGINES, OPERATED BLEEDS, NO ODOR NOTED. OPERATED CABIN OVERHEAD, SIDEWALL, READING, AND PSU LIGHTING. OPENED OVERHEAD BINS, OPENED PSU'S AT ROW 4, BOTH. NO ODORS NOTED. COULD NOT DUPLICATE. RETURNED TO SERVICE.