A Cessna 206 airplane and an Aerospatiale AS350D helicopter collided in midair one-half mile south of the Dillingham Airport, Dillingham, AK. Both aircraft had been communicating with the Dillingham Flight Service Station and had received the appropriate flight advisories. The Cessna was practicing landings, and had just departed runway 19 when it was struck from the left side at an altitude of approximately 400' AGL. The helicopter was on a 14 CFR Part 135 cargo only flight, and was in level cruise or a slight climb at the time of the accident. Witnesses related that neither aircraft took evasive action prior to impact. The helicopter's main rotor hub and tail boom separated prior to ground impact, and the Cessna's tail section separated and right wing folded prior to ground impact. Tail rotor blade strikes were visible on the bottom and right side of the Cessna, and main rotor blade strikes were visible on the right side of the fuselage.