On January 9, 2006, at 1720 central standard time, a Cessna 310R, N310CK, operated by St. Charles Flying Service as a cargo airplane, received substantial damage on impact with a duck during cruise flight about 10 statute miles west of St. Charles County Smartt Airport (SET), St. Charles, Missouri. A fire in the right wing tip tank was first noticed by the pilot after landing. Dusk visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 135 cargo positioning flight had filed but not activated an instrument rules flight plan. The pilot was uninjured. The flight originated from SET and was en route to Jefferson City Memorial Airport, Jefferson City, Missouri, when it returned to SET after the bird strike. The pilot stated that he initially leveled off below class B airspace at 1,500 feet mean sea level (msl), then climbed "another couple of feet" to get an instrument flight rules clearance. At the time of the bird strike, the airplane was at a cruise altitude of 1,900 - 2,000 feet msl and at 145 - 155 knots indicated airspeed. After the bird strike, the pilot looked at the right wing and saw the right wing damaged. He stated that there were no problems controlling the airplane after the impact and everything was "normal". After landing, he made a slow turn onto a taxiway and then saw flickering in the corner of his eye, which were flames from the right wing tip tank. He then exited the airplane and called the local fire department, which arrived 20 minutes later. The fire department did not have foam, and the fire burned for an additional 15-20 minutes until there was an explosion, at which time the fire self-extinguished. The tip tanks were full of fuel. The pilot stated that the top portion of the tip tank was damaged, and the strobe/navigation light assembly was damaged with a broken strobe bulb. The feathers that adhered to the wing were identified as being from a Mallard, which has an average weight of 1,080 grams (2.38 pounds) with a weight range of 500-1,800 grams (1.10 - 3.97 pounds).