As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAD INFLIGHT T2009/27JUL JFK TO UVF. CREW REPORTED CABIN SMOKE DETECTORS SOUNDED DURING FLIGHT THEN STOPPED FOLLOWED BY ELECTRICAL BURNING SMELL. LANDED IAD WITHOUT INCIDENT. NO SIGN OF SMOKE OR SMELL. COULD NOT DUPLICATE. SYSTEM GROUND CHECKED NORMAL OPS. (CLOSED)