Accident Sequence
On September 21, 2020, at approximately 1405 Alaska daylight time, a Cessna 182C airplane, registration N182KT, sustained substantial damage during a landing roll near King Salmon, Alaska. The private pilot, who was the sole occupant, was not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
According to the pilot, after a normal touchdown in crosswind conditions, the left main landing gear (MLG) began to shake and rattle. The shaking intensified as the airplane continued the landing roll, causing it to veer left and depart the runway. As the airplane came to rest, the left MLG spring separated from the fuselage, resulting in substantial damage to the left horizontal stabilizer and elevator.
Post-Accident Examination
An initial examination by the pilot revealed fractures in the left MLG spring U-bolt and the MLG support bolt, allowing the left MLG spring to separate from the fuselage. Subsequent visual and microscopic examination of the left MLG spring attach hardware identified a fatigue crack in the U-bolt. The crack originated in the first thread root of the U-bolt and propagated substantially through the thickness of the thread until it reached a critical size and ultimately failed due to overstress. The MLG bolt was found to have fractured within the shank due to shear loads.