As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 7686-ONT- FLIGHT CREW REPORTED SMOKE IN CABIN AREA AND DECLARED EMERGENCY AND PERFORMED AN AIR-RETURN TO ONT, WHERE IT LANDED SAFELY WITHOUT INCIDENT, AND PASSENGERS WERE DE-PLANED SAFELY. MAINTENANCE PERFORMED HIGH POWER RUNS AND COULD NOT DUPLICATE. OPERATIONALLY CHECKED SATISFACTORY AND ACFT WAS RELEASED TO RETURN FOR SERVICE. (S)