Piper PA-28-181 N4376H accident near Pellston, Michigan

Probable cause

The failure of the left main landing gear strut and clevises due to fatigue cracks that initiated at multiple casting solidification voids.

NTSB analysis

The flight instructor and student pilot had completed two touch and go landings. On takeoff after the second landing, they heard an unusual thumping sound or a bang. Due to the unusual noise, the flight instructor elected to perform a precautionary landing. During the approach for a precautionary landing, the airport manager observed that the left main landing gear wheel assembly was hanging from the landing gear strut by the brake line and advised the flight instructor via radio not to land. The flight instructor then diverted to another airport due to the availability of increased airport fire and rescue services. The airplane landed on the runway centerline with the partially separated left main landing gear assembly and sustained substantial damage to the left wing.

Postaccident examination revealed the landing gear strut housing and clevises were fractured at the upper torque link connection. Metallurgical examination revealed the strut and clevises fractured from fatigue cracks that had initiated along the radius of the clevis arms within the inner machined surface. These cracks initiated at multiple casting solidification voids and silicon-rich phases. The cracks propagated through the clevis cross-sections until the remaining cross-sections fractured from overstress.

Text from the NTSB. Open the NTSB docket for CEN23LA217 for the full record.