Pilot Debrief

CESSNA U206C near Challis, ID — 2023-09-20

Final reportWPR23LA350
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Date
2023-09-20
Location
Challis, ID, USA
Airport
U54
Aircraft
CESSNA U206C
Registration
N3923G
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Takeoff roll

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.

Contributing factors

Contributing to the accident was the improper maintenance on the landing gear spring assembly which allowed corrosion to develop.

NTSB narrative

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.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Inspection of main gear springs could have identified issues before takeoff.

NTSB coding

Evidence available

  • Photos
  • 6 docket documents
View NTSB final reportView NTSB docket

Docket documents6

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