20011212036529A

(-23) N7007F was enroute from milwaukee timmerman fld to the east troy airport, east troy WI. The weather was IFR and deteriorating. Enroute the aircraft struck a powerline top static cable, in fog & drizzle, then descended at a high rate of descent, struck a truck with a rotor blade on interstate I-43, & impacted the ground. (.19) on December 12, 2001, about 1822 central standard time, a Robinson R44 helicopter, N7007F, piloted by an instrument rated commercial helicopter pilot, was destroyed when it impacted interstate highway 43 near Waukesha, Wisconsin. Four motor vehicles were damaged. The helicopter impacted one of the motor vehicles and the remaining three motor vehicles sustained minor damage. The flight was operating under 14 CFR part 91. Visual to instrument meteorological conditions prevailed in the area at the time of the accident. No flight plan was on file. The pilot was fatally injured, one motor vehicle occupant sustained serious injury, and one motor vehicle occupant sustained minor injury. The seriously injured occupant was transported to a local hospital for medical treatment. The positioning flight originated about 1810 from the lawrence j. timmerman airport (mwc), near milwaukee, Wisconsin, and was destined for east troy municipal airport, near east troy, Wisconsin. A witness, who had been a passenger on the flight immediately prior to the accident flight, stated: at approx. 4:40 pm we launched from mwc after taking on fuel. We flew to a tannery fire at 3rd [and] Oregon approx 5 mi. North of mke [general mitchell international airport]. We orbited the fire taking pictures until approx 6 pm. We then returned to mwc. I exited the aircraft at approx. 6:10 pm and the pilot told me he was going back to the east troy airport to hangar the aircraft. At the time it was dark [and] cloudy with drizzle. A witness who had been driving in a motor vehicle stated:we were the third vehicle directly in the path of the helicopter, approx 1/4 mi. In front of our vehicle. I, ..., was driving and saw a red light over what seemed like the median a few 100 ft. in the air. The light rose almost straight upward maybe another 200 ft and then began corkscrewing downward. It was very foggy and difficult to see anything. We stopped, turned on our yellow strobe and hazard flashers, and went up to check the pilot. My wife telephoned 911 for help. At 1745, the mwc weather, about 15 miles northwest of the accident site, was: wind 150 degrees at 5 knots; visibility 4 statute miles; present weather mist; sky condition overcast 1,400 feet; temperature 7 degrees c; dew point missing; altimeter 29.94 inches of mercury. At 1845, the mwc weather was: wind 150 degrees at 5 knots; visibility 3 statute miles; present weather mist; sky condition overcast 800 feet; temperature 6 degrees c; dew point missing; altimeter 29.90 inches of mercury. At 1745, the Waukesha county airport (ues), near Waukesha, Wisconsin, weather, about 10 miles north of the accident site, was: wind calm; visibility 2 statute miles; present weather mist; sky condition overcast 600 feet; temperature 7 degrees c; dew point 7 degrees c; altimeter 29.91 inches of mercury. At 1845, the ues weather was: wind 120 degrees at 5 knots; visibility 1 statute miles; present weather drizzle; sky condition overcast 400 feet; temperature 7 degrees c; dew point 7 degrees c; altimeter 29.87 inches of mercury. At 1815, the burlington municipal airport (buu), near burlington, Wisconsin, weather, about 15 miles south of the accident site, was: wind calm; visibility 1 1/4 statute mile; sky condition overcast 300 feet; temperature 7 degrees c; dew point 7 degrees c; altimeter 29.89 inches of mercury. At 1835, the buu weather was: wind 110 degrees at 3 knots; visibility 1 statute mile; sky condition overcast 300 feet; temperature 7 degrees c; dew point 7 degrees c; altimeter 29.88 inches of mercury. The helicopter came to rest on the northbound lanes of interstate highway 43 about 200 feet southwest of power lines that cross the highway near its intersection with state highway 164. The area was photographed and the helicopter wreckage was relocated to a hangar. An on-scene investigation was conducted. The carburetor was found detached from the engine. Throttle, mixture, and carburetor heat control continuity was traced from the cockpit to the engine. Control continuity was traced to all flight control surfaces. The engine rotated and produced a thumb compression at all cylinders. A magneto produced spark at five of its six leads. The remaining lead was found torn and a spark was observed at the torn section. The fiberglass chin portion of the front right side of the cabin exhibited a linear tear. The right side forward and aft cabin doors exhibited a linear scratch across them. The right navigation light assembly was found with a semicircular deformation. The tailskid exhibited a semicircular deformation on its surface. The red navigation light filament was found stretched. The helicopter's color scheme was blue with white and red lettering and graphics. The tail rotor guard was colored red and white. A power line maintenance helicopter observed the power lines that crossed the highway. A maintenance crewmember reported that a line on the southwest side exhibited a blue, white, and red colored media on it. He reported that he observed a fibrous media on that line.