Probable cause
The failure of the left main landing gear spring assembly due to a fatigue crack. Contributing to the accident was the improper maintenance on the landing gear spring assembly which allowed corrosion to develop.
NTSB analysis
The pilot was in the process of taking off when the left main gear spring assembly fractured. The airplane veered off the runway and ground contact substantially damaged the left horizontal stabilizer and elevator.
Metallurgical examination of the failed gear spring assembly revealed it failed due to fatigue cracking and overload stresses. Further examination revealed corrosion underneath the primer paint and inside the dimples of the shot-peened area, which likely initiated the development of the fatigue crack.
A records review revealed that in March of 2010, the left and right main gear spring assemblies were inspected, heat treated, shot peened and painted with a zinc-rich primer. It is likely that corrosion existed on the landing gear before the application of the primer paint, and that the inadequate removal of the corrosion allowed fatigue cracking to propagate until the left assembly failed in overstress.
Text from the NTSB. Open the NTSB docket for WPR23LA350 for the full record.
Event
- Date
- Sep 20, 2023
- Type
- Accident
- Place
- Challis, Idaho
- Nearest airport
- Bernard Usfs (U54)
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Cessna U206C
- N-number
- N3923G
- Category
- Airplane
- Year built
- 1967
- Damage
- Substantial
- Operating rule
- Part 135 (charter and commuter)
- Purpose of flight
- Business
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.