HISTORY OF FLIGHTOn October 05, 2022, about 1758 Alaska daylight time, a Cessna 185F, N217C, was not damaged when it was involved in an accident near Fairbanks, Alaska. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. A witness located next to the waterway stated that the pilot attempted and subsequently aborted the first takeoff. The pilot then began taxiing back to the point of the initial takeoff run. The witness stated that the engine appeared to be operating at full power during the takeoff attempt. During the taxi back following the aborted takeoff, the airplane’s attitude was nose-low and the floats were almost completely submerged underwater. Another witness on the other side of the float pond noted that the accident airplane’s floats looked almost fully submerged under water as the airplane taxied. The witness said that the airplane was using more than normal power to taxi in the water and that the elevators appeared to be in the full nose-up position. He then heard the engine power decrease, saw the airplane start to nose over, heard the power increase, and then observed the airplane completely nose over into the water. When the airplane was pulled up on the shore, a witness observed four large streams of water coming out of the front of both floats. AIRCRAFT INFORMATIONAbout 95 pounds of cargo was located in the left float hatch. A total of about 838 pounds of cargo was in the airplane. AIRPORT INFORMATIONAbout 95 pounds of cargo was located in the left float hatch. A total of about 838 pounds of cargo was in the airplane. WRECKAGE AND IMPACT INFORMATIONThe airplane sustained no impact damage in the accident. All damage to the airframe was sustained during the recovery and rescue attempt of the pilot. During a postaccident examination of the floats, two unplugged holes were found under each front float bumper. The pilot’s son said that when the airplane arrived in Alaska, the standard float bumpers were not installed and a tire-type material was installed as a bumper instead. The correct smaller bumpers were installed at the time of the accident, with new-looking sealant around the bumper. 4 holes had been added to the front of each float to attach the larger, tire-type bumper; however, only the two side holes had been plugged and sealed. The two lower holes were left open. A Federal Aviation Administration inspector examined the underside of each float and found patches that did not appear to be watertight on the bottom. A witness stated that the pilot kept this airplane on the shore when it was not in use. SURVIVAL ASPECTSUnrestrained cargo in the cabin shifted forward during the event sequence and rescuers were unable to free the pilot from the cockpit. About 690 pounds of cargo had to be removed before rescuers could free the pilot from the airplane.