Cessna 305 N1834 accident near Wurtsboro, New York

Probable cause

A fatigue fracture of the left main landing gear axle.

NTSB analysis

After completing five glider tow flights, the commercial pilot landed the airplane on the turf runway. During the landing roll, the left main landing gear wheel separated from the axle; the airplane nosed over and came to rest inverted, which resulted in substantial damage to the rudder and wings.

Postaccident examination revealed that the axle of the left main landing gear assembly was fractured near the end that would have been attached to the landing gear strut. There were two opposing fatigue regions on the fracture surface separated by an overstress region. The first fatigue region had a shiny appearance consistent with recontact of the fracture surfaces. The second fatigue region exhibited a more matte appearance and covered a larger area than the first region. In addition, the tread of the rubber tire exhibited a wear pattern that was not centered but instead had shifted toward the shoulder.

It is possible that the axle had a crack for an unknown amount of time, then was reassembled 180° rotated when it began to fatigue again on the opposing side. As a result of the canting of the wheel because of the larger fatigue crack, the wear pattern of the tire shifted from the centerline to the shoulder of the tire. According to the maintenance records, the most recent annual inspection was performed about 12 months before the accident, which would have been the most recent time the landing gear system was completely examined. Since the origination time of the crack is unknown, the investigation could not determine if the mechanic performing the most recent annual inspection would have been able to see and identify the fatigue fracture.

Text from the NTSB. Open the NTSB docket for ERA17LA298 for the full record.