What was found
FLIGHT 3789, RIGHT AFTER TAKEOFF CREW REPORTED RECEIVING A LAVATORY SMOKE MESSAGE ON EICAS. FOLLOWED AOM PROCEDURES & REQUESTED CRASH, FIRE & RESCUE UPON LANDING. ELECTED TO RETURN TO FIELD & LANDED WITHOUT INCIDENT. AFTER LANDING, FIRE DEPARTMENT INFORMED CAPTAIN THAT IT APPEARED THAT THE RT OUTBOARD BRAKE WAS FROZEN & NR 4 TIRE DRAGGING. NO OTHER EICAS MESSAGES NOTED. ACFT REMOVED FROM SERVICE. R & R NR 4 MLG BRAKE ASSY IAW 32-600-14. R & R NR 4 MLG TIRE IAW 32-700-11. R & I SERVICEABLE SMOKE DETECTOR IN LAVATORY IAW 26-12-01. TEAR DOWN REPORT INDICATES CAUSE OF SMOKE IN ENGINE 1 DUE TO FAILURE OF NR 4 CARBON SEAL. ACFT RETURNED TO SERVICE.