While the aircraft was descending to land at Canberra the forward toilet smoke detector activated, the flight deck smoke annunciate light illuminated and a small amount of smoke was visible on the flight deck. The flight attendant confirmed there was no evidence of fire in the toilet. A slight haze was visible in the cabin with wisps emanating from the air-conditioning vents. The crew continued with the landing and a normal disembarkation ensued.
Oil was found to be dripping from the engine which was removed for rectification. The number 1 air/oil seal was found to have delaminated allowing engine oil to permeate into the air-conditioning ducts. The seal had previously been repaired at the manufacturer's facility. After this incident the operator determined to use only newly manufactured seals and introduced an in-situ pressure test of the seal.