Cessna 140 N3625V accident near Independence, Oregon

Probable cause

The failure of the left main landing gear wheel axle due to a fatigue crack.

NTSB analysis

The private pilot was landing the airplane on a dry, hard-surfaced runway. He stated that the approach and touchdown were normal. Just after touchdown, he felt "something similar to a bump," and the airplane started to drift to the left. He thought that the airplane possibly had a flat tire and tried to compensate with rudder input, but the airplane continued drifting to the left, exited the left side of the runway, and ground looped, resulting in substantial damage to the right wing and fuselage.

An on-scene examination revealed that the left main landing gear axle had fractured, resulting in the separation of the wheel assembly. A detailed examination revealed that the axle was fractured near the inboard end, just outboard of the axle attachment flange. Portions of the fracture surface at the upper and lower sides of the axle had relatively smooth features oriented perpendicular to the outer surface, consistent with fatigue. The fatigue cracks initiated at a fillet corner at a change in the axle's outer diameter.

The manufacturer specified inspection intervals to check for cracks and corrosion of the main landing gear axle; however, the accident airplane's maintenance logs were not located, and the airplane's maintenance history could not be determined.

Text from the NTSB. Open the NTSB docket for WPR16LA068 for the full record.