What was found
(CAN) REPORTS OF LAV SMOKE CAUTION MSG COMING ON. PROBLEM APPEARS TO HAVE BEGUN ON DEC 5,2006 FLT. 8620, ON CLIMB-OUT, CREW RECEIVED A LAV SMOKE DETECT CAUTION LIGHT, FA CHECKED LAV NO SMOKE WAS EVIDENT, FLIGHT RETURNED TO DEPARTURE. A/C WAS DE-ICED PRIOR TO DEPARTURE AND DE-ICE FLUID WAS THE SUSPECTED CAUSE. BOTH COALESER BAGS WERE REPLACED AND GROUND RUNS WERE CARRIED OUT. A 2ND EVENT OCCURRED ON THE GROUND , DEC 5,2006, LAV SMOKE MSG CAME ON FOR 30 SEC’S THEN DID NOT COME ON AGAIN, C/B’S WERE RESET AND A/C WAS POWERED DOWN AND RESET, FUNCTION CHECKED SERVICEABLE. 3RD EVENT, JANUARY 17, 2007, FLT. 7690, SHORTLY AFTER ROTATION, FLIGHT CREW RECEIVED A SMOKE IN THE LAV INDICATION AND FA CONFIRMED LAV SMOKE D