Cessna 175 N9343B accident near Hot Springs, South Dakota

Probable cause

The tensile overload failure of the main landing gear attachment bolt, which resulted in separation of the left main landing gear and a loss of control during landing.

NTSB analysis

The pilot reported the airplane touched down “with a gentle skip then easing forward on the yoke pinned my main gear firmly on the turf.” During the landing roll, the airplane began to veer to the right, and the pilot applied rudder inputs to correct. The airplane subsequently spun around and came to rest upright with the left main landing gear leg separated. The airplane sustained substantial damage to the left wing and main landing gear box structure. An attachment bolt for the left main landing gear strut was found fractured and separated from the strut.

Metallurgical examination of the fractured bolt and the landing gear strut plate revealed the bolt fractured due to tensile overload that led to shearing of the bolt threads. The bolt was fully threaded into the self-locking nut plate and there was no evidence of looseness before the failure. The damage pattern of the fractured bolt and bent strut plate were consistent with an overload failure of the inboard attachment with no evidence of any preexisting damage or weakness in the attachment. It is likely the main landing gear failure was the result of excessive loading on the attachment during the landing.

Text from the NTSB. Open the NTSB docket for CEN21LA416 for the full record.