On September 25, 2004, about 1400 Alaska daylight time, a float-equipped Piper PA-12 airplane, N4409M, sustained substantial damage during a hard water landing, following a loss of engine power during initial climb after takeoff from a lake, about 10 miles north of Nenana, Alaska. The airplane was being operated by the pilot as a visual flight rules (VFR) personal cross-country flight under Title 14, CFR Part 91, when the accident occurred. The solo commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on October 24, the pilot said he had just lifted off the lake and started to climb, when the engine lost power and the airplane descended rapidly, landing hard on the water. The pilot said he did not know why the airplane lost engine power, and that there were no known mechanical anomalies with the airplane prior to the accident. The airplane was recovered to Fairbanks, Alaska, via helicopter. During a telephone conversation with the NTSB IIC on October 5, the FAA aviation safety inspector who inspected the airplane at Fairbanks, said the lower fuselage longerons were bent, and major airframe tubing repairs were needed. During a telephone conversation with the NTSB IIC on January 25, 2005, the mechanic who was repairing the airplane said the engine was running fine, and he was unable to find any mechanical cause for the loss of power.