As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT INTO BWI, AT LOW POWER SETTINGS, NOTICED A HOT BURNING ODOR IN COCKPIT AND CABIN. TROUBLESHOT AND FOUND ODOR EMITTING FROM LIGHT FIXTURE ABOVE SEAT 4AC. DISABLED FIXTURE AND ISSUED MEL. APU BLEED ALSO RENDERED INOPERATIVE PER MEL, DUE TO ODOR COMING FROM IT. AIRCRAFT RETURNED TO SERVICE. (M)