AN EMB145 ON INITIAL CLB AT 1000 FT DECLARED AN EMER AND DIVERTED DUE TO 'LAVATORY SMOKE' WARNING; TRIPLE CHIME AND CABIN ATTENDANT ADVISING SMOKE IN CABIN.

Narrative

ON INITIAL CLB OUT OF ZZZ AT ABOUT 1000 FT; 'LAVATORY SMOKE' WAS PRESENTED ON THE EICAS WITH THE ASSOCIATED TRIPLE CHIME. THE FLT ATTENDANT CALLED WITH THE CABIN EMER ADDRESS BUTTON AND STATED THAT THE CABIN WAS FULL OF SMOKE. WE DECLARED AN EMER AND ADVISED APCH CTL THAT WE NEEDED AN IMMEDIATE RETURN TO THE FIELD. APCH CTL TOLD US TO LEVEL AT 3000 FT AND TURN TO A N HDG. WE COMPLETED THE APPROPRIATE MEMORY ITEMS PER THE 'CABIN FIRE OR SMOKE' CHKLIST AND CONDUCTED THE 'LAVATORY SMOKE' CHKLIST. IT REFERRED US TO THE 'CABIN FIRE OR SMOKE' CHKLIST; HOWEVER; WITH THE PWR REDUCTION AND RECIRCULATION FANS OFF; THE FLT ATTENDANT ADVISED US THAT THE SMOKE HAD COMPLETELY DIMINISHED. THE EICAS MESSAGE WENT AWAY AS WELL. WE CONDUCTED THE REST OF THE FLT USING SOP'S; LANDED SAFELY; AND RETURNED TO THE GATE WITH NO FURTHER INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS AIRPLANE HAD THE SAME INCIDENT THE PAST 3 DAYS AND ALWAYS THE FIRST FLT OF THE DAY. AFTER THE ENGS ARE HEATED UP; THE PROB IS GONE FOR THE REST OF THE DAY. WE KNOW THE PROB IS AN OVERNIGHT STAY IN COLD WX WHEN A BEARING SEAL LEAKS OIL INTO THE COMPRESSOR SECTION AT OR NEAR THE ENG PNEUMATIC BLEED. THIS ENG WAS RUN AT HIGH PWR WHEN WE RETURNED WITH THE SAME RESULT 'UNABLE TO DUPLICATE RPT.' THE ENGS ARE ALLISON-ROLLS ROYCE.