On September 19, 1998, about 0730 Alaska daylight time, a float equipped de Havilland DHC-2 airplane, N700NL, sustained substantial damage during an attempted takeoff from Lake Iliamna, Alaska, about 20 miles southwest of Iliamna, Alaska. The solo commercial pilot was not injured. Visual meteorological conditions prevailed for the local, 14 CFR Part 91 fishing lodge business flight. The flight was returning to Nondalton, Alaska, where it had departed about 0700. During a telephone interview with an NTSB investigator on September 19, the pilot reported he was beginning a takeoff run to the east, when the right wing lifted and the airplane rolled slowly to the left and nosed over. The pilot said he estimated the winds at the time of the accident to be from the east at 30 to 40 knots. He also noted there were no preaccident mechanical problems with the airplane. During the telephone conversation with the NTSB investigator, the pilot indicated there was damage to the left aileron. The aileron was subsequently replaced. In his written report to the NTSB, the pilot wrote that as he advanced power for takeoff, an "unknown" gust of wind lifted the right wing and rolled the airplane over to the left. His report also estimated the wind to be from the east at 35 knots, with gusts to 55 knots.