Cessna 182
King Salmon, AK — September 21, 2020
Event Information
| Date | September 21, 2020 |
| Event Type | ACC |
| NTSB Number | ANC20LA098 |
| Event ID | 20200923X61025 |
| Location | King Salmon, AK |
| Country | USA |
| Coordinates | 58.67278, -156.64250 |
| Airport | King Salmon |
| Highest Injury | NONE |
Aircraft
| Make | Cessna |
| Model | 182 |
| Category | AIR |
| FAR Part | 091 |
| Aircraft Damage | SUBS |
Conditions
| Light Condition | DAYL |
| Weather | VMC |
Injuries
| Fatal | 0 |
| Serious | 0 |
| Minor | 0 |
| None | 1 |
| Total Injured | 0 |
Event Location
Probable Cause
The fatigue fracture failure of the left main landing gear U-bolt during landing, which resulted in the collapse and separation of the left main landing gear spring.
Full Narrative
On September 21, 2020, about 1405 Alaska daylight time, a Cessna 182C airplane, N182KT, sustained substantial damage when it was involved in an accident near King Salmon, Alaska. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 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 continued and became more severe as the airplane continued the landing roll, and the airplane subsequently began to veer to the left and exited 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.
An initial examination of the airplane by the pilot revealed that the left MLG spring U-bolt and MLG support bolt fractured, allowing the left MLG spring to separate from the fuselage.
A visual and microscopic examination of the left MLG spring attach hardware revealed a fatigue crack in the U-bolt that emanated 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. Examination of the MLG bolt revealed that the bolt fractured within the shank due to shear loads.
About This NTSB Record
This aviation event was investigated by the National Transportation Safety Board (NTSB). NTSB investigates all U.S. civil aviation accidents to determine probable cause and issue safety recommendations to prevent future accidents.