Employee suffered the amputation of three fingers while working on the south in-bed fuel airlock in the energy building. He was using a hammer to hit the outside of the chute to loosen built up saw dust. The chute leads to an airlock, which feeds the blow line to the boiler. He removed the panel cover over the airlock to see if the saw dust was falling in. He slipped and his left hand entered the airlock. Contact with the rotating parts in the airlock resulted in the multiple-finger amputation.