Nose Gear Collapse Following Torque Link Bolt Failure (N4863C)

Investigation Findings

The investigation revealed that the nose gear torque link bolt failed by shearing during the landing roll on an abandoned sand airstrip. This failure caused the nose gear to collapse, leading the aircraft to nose over. The shear occurred at the interface between the bolt and its sleeve.

Metallurgical Testing

Metallurgical testing of the failed bolt and sleeve disclosed evidence of a long-term progression of severe corrosion between the bolt and the sleeve. The corrosion had been developing over an extended period and was significant in extent.

Operational History

The aircraft had been involved in operations that required multiple takeoffs and landings per hour. Many of these operations were conducted on salt water beaches, exposing the aircraft to corrosive salt spray and sand. This operational environment provided conditions conducive to corrosion development.