On September 1, 1997, about 1630 Alaska daylight time, a Cessna U206E airplane, N9129M, was substantially damaged when it nosed over during landing at the Tatitna landing strip, seventy three miles east of McGrath, Alaska. The airline transport certificated pilot was uninjured. The front seat passenger sustained minor injuries. The back seat passenger sustained a serious neck injury. The airplane was operated by Alaska Air Taxi, of Anchorage, Alaska. The flight was conducted under 14 CFR Part 135 as an on demand air taxi from Anchorage to the Tatitna strip. The flight departed Lake Hood strip at 1530. Visual meteorological conditions prevailed at the time of the accident, and a company flight plan was filed. The pilot said that upon landing, the nose gear collapsed and the airplane nosed over onto its back. Witnesses on the ground, and the passengers, observed the airplane land hard and bounce into the air. The passengers said the airplane bounced twice, and on the third touchdown, nosed over. Both passengers stated that the landing was slightly downwind. The engine and empennage both separated from the airplane. The nose landing gear assembly had been installed on the airplane twelve days prior to the accident. Inspection of the nose wheel, strut, and forks, revealed permanent deformation to the left. Further microscopic inspection of the failed components at the NTSB metallurgical laboratory revealed fractures typical of right to left overstress. A small region of fatigue was observed at the forward bolt hole of the right fork. Neither passenger had their seatbelt fastened. Both passengers said that the cargo was not restrained, and had been placed on top of the rear seat passenger's lap belt, and that there was no belt available for the rear seat occupant. The passenger seated in the right, front seat said that his belt and shoulder harness were both available, but he did not wear them. During the accident sequence, the cargo struck the rear seat passenger.