On August 13, 2003, about 1900 Alaska daylight time, a float-equipped Cessna 206 airplane, N59352, sustained substantial damage when the airplane's floats collided with an ocean wave during the takeoff run from Francis Cove, Alaska, a remote saltwater bay about 24 miles north of Ketchikan, Alaska. The airplane was being operated as a visual flight rules (VFR) on-demand charter flight under Title 14, CFR Part 135, when the accident occurred. The airline transport certificated pilot, and the three passengers, were not injured. Visual meteorological conditions prevailed, and a company flight plan was filed. The flight was originating at the time, and was en route to Ketchikan, with a planned stop at Fire Cove, Alaska. During a telephone conversation with the National Transportation Safety Board investigator-in-charge on September 10, the pilot reported that while departing from Francis Cove, just as the airplane's floats came on step, the floats contacted a large wave, which bounced the airplane about 15 feet into the air. He said that as the airplane descended towards the water, a second wave struck the floats. The pilot said that he was able to continue the takeoff, and proceed to his next planned destination. The pilot reported that after landing at Fire Cove, a postlanding inspection failed to disclose any damage to either the airplane's fuselage or floats. After the flight returned to Ketchikan, and after the airplane was removed from the water at the end of the day, the operator's maintenance personnel discovered minor wrinkling of the forward portions of the fuselage, adjacent to the forward float attach points. A detailed inspection was completed, which revealed structural damage to longerons adjacent to the airplane's firewall, requiring replacement of the longerons. The pilot reported that there were no preaccident mechanical problems with the airplane.