Narrative:

Lavatory smoke EICAS warning at 500 AGL. Advised ATC and setup to return to [departure airport]. Ran QRH for EICAS message and completed emergency landing checklist. Landed underweight. Did not evacuate at guidance of aircraft rescue and fire fighting (arff). Taxied to gate with arff following. Wrote up in logbook. Mechanic mentioned a recent engine change on our airplane.

Google
 

Original NASA ASRS Text

Title: EMB190 Captain experienced a lavatory smoke EICAS at 500 feet AGL after takeoff and returned to the departure airport.

Narrative: Lavatory smoke EICAS warning at 500 AGL. Advised ATC and setup to return to [departure airport]. Ran QRH for EICAS message and completed emergency landing checklist. Landed underweight. Did not evacuate at guidance of Aircraft Rescue and Fire Fighting (ARFF). Taxied to gate with ARFF following. Wrote up in logbook. Mechanic mentioned a recent engine change on our airplane.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.