Accident Details
On March 7, 2025, at about 1400 Alaska standard time, a ski-equipped Cessna 185 (registration N1718R) was taxiing for takeoff from a remote snow-covered lake near Skwentna, Alaska. During taxi, the right main landing gear leg collapsed, resulting in substantial damage to the landing gear box assembly and door post assembly. The pilot and two passengers were not injured. The flight was conducted as a personal flight under Title 14 Code of Federal Regulations Part 91.
Maintenance History
According to maintenance records, the airplane had accumulated about 83 flight hours between May 2023 and the accident. The owner reported that in October 2023, the floats and float rigging were removed, and the main landing gear with wheels was installed. However, a review of the maintenance records did not document this alteration. Further review indicated that the wheels were removed in December 2023 and skis were installed on the main landing gear legs.
The mechanic who performed the landing gear change in October 2023 stated that he did not recall the specific hardware used but, when performing such work, he relies on hardware provided by the owner. When asked why no entry was made in the maintenance logbook for the landing gear assembly change, the mechanic explained that the owner never provided the logbooks for him to sign.
Hardware Examination
The installed hardware on the main landing gear spring consisted of an AN7-20 bolt with a cross-drilled hole through the threaded portion and an MS20365-720A nylon locking nut. Per the Cessna 180 and 185 Parts Catalog, the correct hardware for the inboard end of the main landing gear spring should be an AN7-20A bolt (without cross-drilled hole), an MS20365-70C all-metal locking nut, and a spring adjustment shim.
Both the bolt and nut were submitted to the NTSB Materials Laboratory for examination. The bolt showed patchy and faint remnants of cadmium plating on the flats of the head, and no remaining cadmium plating on the shank. Its composition and hardness were consistent with typical AN-type bolt specifications. The nut exhibited worn and patchy cadmium plating. Both components displayed worn threads. The worn threads near the end of the bolt contained bits of the nut's nylon locking insert. The nylon locking insert was worn down to the depth of the worn threads inside the nut; the wear pattern indicated gradual thread wear over time rather than a sudden overload event.
Conclusions
The accident resulted in substantial damage to the aircraft. No injuries were reported. The investigation examined maintenance documentation and hardware discrepancies, but the report does not assign a probable cause.