Cessna 172RG N6272R accident near Carson City, Nevada

Probable cause

The overload failure of the landing gear actuator at an undetermined time.

NTSB analysis

During the landing approach the pilot was unable to fully extend the right main landing gear. Following multiple troubleshooting attempts he retracted the left and nose landing gear and performed a partial gear-up landing. During the landing sequence the airplane sustained substantial damage to the belly structure. Postaccident examination revealed multiple fractures in the right main landing gear actuator housing and mechanical damage to the internal piston rack. Analysis of the fractures revealed that they had failed in overload. Examination of an exemplar actuator, piston, and sector gear revealed that the mechanical damage to the teeth on the sector gear occurred after the initial failure of the actuator housing and was not causal to the failure. The airplane manufacturer had released a service bulletin addressing repeated inspections for cracks at a specific location in the actuator body, a typical procedure for monitoring of fatigue cracks. Although it appeared that the operator had not complied with the service bulletin, the primary cracks were in a different location and displayed features consistent with an overload event. Although the airplane had been used for flight training, and the overload failure of the actuator was likely caused by a prior hard landing, the investigation was unable to determine the initiating event.

Text from the NTSB. Open the NTSB docket for WPR09LA083 for the full record.