SEA01LA022

The pilot began a takeoff run to the west, planning a left step turn and liftoff to the south. Just after starting the step turn, while on the step at a speed of about 40 knots in 'a normal left turn step attitude', and 'skidding and bouncing a bit to the right through the chop as is normal in the step turn', the pilot was violently thrown to the right, striking his head on the right side door post (despite having his seat belt and shoulder harness on.) He reported that he was heading about west to southwest when this occurred. The plane came to an instantaneous stop at this point. Investigators did not find any evidence of aircraft malfunctions occurring prior to the sudden stoppage in the water.

On December 1, 2000, approximately 1130 Pacific standard time, an Aerofab Lake 250 amphibious airplane, N8551Z, registered to and operated by the pilot, was substantially damaged in a takeoff attempt from the surface of Lake Washington near Mercer Island, Washington. The private pilot-in-command received minor injuries in the accident. Visual meteorological conditions prevailed and no flight plan was filed for the 14 CFR 91 personal flight. The pilot did not report the accident flight's destination.

The pilot indicated that at the time of the takeoff attempt, the wind was 3 to 5 knots from the south, and there was about 6 to 10 inches of chop on the water. He reported there was no nearby boat traffic and no noticeable wakes or swells. The pilot stated he began his takeoff run to the west, planning a left step turn and liftoff to the south. He reported that just after starting the step turn, while on the step at a speed of about 40 knots in "a normal left turn step attitude", and "skidding and bouncing a bit to the right through the chop as is normal in the step turn", he was violently thrown right, striking his head on the right side door post (despite having his seat belt and shoulder harness on.) He reported that he was heading about west to southwest when this occurred. He stated the plane came to an instantaneous stop at this point. The pilot subsequently radioed for assistance. Several boats came to the aid of the stricken aircraft and rescued the pilot. The aircraft then began to sink, but the aid boats were successful in placing flotation gear underneath the aircraft. This prevented the aircraft from sinking and enabled it to be towed to shore.

According to the pilot, the accident aircraft had 830 hours airframe total time since new, and the aircraft had received its last annual inspection on November 24, 2000, 1.5 flight hours before the accident. The pilot reported that after the accident, he noted that the aircraft's engine, which is mounted on a dorsal pylon above the fuselage, had toppled onto the right wing. The pilot stated that this was possibly due to a "pylon flying wire root block Uchannel [sic] failure", although he further stated that this was "most likely a result, not a cause of the accident." A representative of Talon Aviation, Puyallup, Washington, brought a fractured component he reported to be this suspect component to the NTSB Northwest Regional Office in Seattle, Washington, for examination. The NTSB IIC visually examined the component and observed that the fracture surfaces on the component displayed 45-degree shear lips. The IIC did not observe any areas of scalloping or "beach marks" on the component's fracture surfaces.