What was found
ON APPROACH WITH ENGINE ANTI-ICE ON, AFT SMOKE DETECTORS WENT OFF AND THERE WAS SMOKE IN THE CABIN. REPLACED WATER SEPARATOR BAGS AND LEAK CHECK OK. CHECKED ACM OIL, FOUND OK. FOUND HYD OVERFLOW CAN OVERFLOWING, EMPTIED SAME AND RAN ENGINES PACKS ANTI-ICE, APU COULD NOT DUPLICATE.