What was found
YUL - FLT 4009 - CREW REPORTED SMOKE IN AIRCRAFT AFTER TAKEOFF SUSPECT NR 1 PACK. MAINTENANCE DISPATCHED TO YUL, PERFORMED HARD/OVERWEIGHT LANDING INSPECTION AND RELEASED A/C IAW MEL NR 21-51-00 CATERGORY C PLACARD NR 003822. AIRCRAFT RETURNED TO SERVICE. ON NEXT TAKEOFF SMOKE REPORTED IN A/C. AFTER TAKEOFF SUSPECT NR 2 PACK. MAINTENANCE SUSPECTED DE-ICE FLUID IN APU INLET CAUSING SMOKE. TEST FLIGHT OF AIRCRAFT REQUIRED BEFORE RETURN TO SERVICE. AIRCRAFT TEST FLEW SATISFACTORY TO EWR. AIRCRAFT RETURNED TO SERVICE. (M)