A BE-55 pilot reported a wake vortex encounter while on approach to LOU from an air-taxiing helicopter; resulting in a temporary loss of control.

Narrative

While I was 5 miles out on IFR plan on approach to Runway 24 at LOU a helicopter was cleared to cross the path to Runway 24. The helicopter asked Bowman Tower twice if they were sure that they were cleared to cross the runway. I didn't think anything about it myself. At 200 FT from ground on final; my plane had forces that felt like the entire plane was pushed down. Then I had a violent 45 degree pitch to the left and stall horn going off. I pushed the nose over thinking it was wind shear on approach. I leveled out and gained control of the plane. Within seconds my plane was in a 45 degree bank to the RIGHT. At this point I executed full power and a go-around. After regaining composure and flight attitude I noted to the Tower that I believed I had flown into wake turbulence from the helicopter that was still taxiing to the FBO. No reply came from Tower. A second radio operator queried the Tower if I had stated the wake turbulence caused the issue. A Controller answered that I had stated that; but he had just came on and was not in position to see my plane. The lineman on the ground stated that he was looking for a place to run based on the visuals he saw of my plane coming pitched down toward the FBO.