20010716016519A

(.19) On July 16, 2001, approximately 1720 pacific daylight time, a Piper PA-12 floatplane, N918TF, registered to an individual, and being flown by a private non-floatplane rated pilot accompanied by a floatplane rated airline transport pilot, sustained substantial damage when the aircraft impacted a log during step taxi to takeoff in the williamette river, Oregon City, Oregon. Both pilots exited the aircraft as it sank, and were uninjured. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was instructional, was operated under 14CFR91, and originated locally on the late afternoon of the accident. The airplane transport rated pilot, a certified flight instructor, reported that the pilot under instruction (seated forward) had just landed on the williamette river reversed direction and was step taxiing to takeoff when the aircraft's right float impacted a tree stump protruding approximately 15 inches above the surface of the water. He stated that he felt the impact and the aircraft's rightfloat became airborne while the left wing dipped. The left wing then impacted the water and the aircraft came to a stop upright in the water. The rig ht float, which had been breached, began to fill with water and the aircraft gradually nosed over while sinking. The engine was shut down and both pilots evacuated before the aircraft became inverted. (-23) CFI gunderson (back seat) and student nicolai (front seat) were practicing landings on the williamette river. It was a training flight. The weather was VFR. Following a downstream landing, the aircraft was turned up river and step taxied by nicolai toward the point of landing. The right float struck a large tree stump which extended approximately 15 inches above the water. The impact substantially damaged the right float and caused the left wing to strike the water. It was also substantially damaged. The aircraft stopped and the engine was shut down. Water filled the float and the aircraft tipped forward. The pilots evacuated the aircraft before it rolled inverted in the water. They were taken from the river by boat.