Casualties unknown

2007-05-30: Cessna A185F (N104DE) — Shearer, ID

Shearer, ID, US

On May 30, 2007, a Cessna A185F (registration N104DE) was involved in an aviation accident near Shearer, ID. Investigators recorded the probable cause as: The fracture occurred due to fatigue cracks that emanated from the chamfer areas at two bolt hole locations on the inboard side of the strut. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

Post-accident metallurgical examination revealed that fatigue cracks originating at bolt hole chamfers caused the left main landing gear to separate during the landing roll.

Accident

During the landing roll, the left main landing gear separated from the aircraft.

Metallurgical Examination

A post-accident metallurgical examination determined that the fracture resulted from fatigue cracks. These cracks originated in the chamfer areas at two bolt hole locations on the inboard side of the strut. The propagation time for the fatigue crack regions could not be established, but most of the brown region fractured in a single event. Because the crack was present for very few flight cycles, a visual inspection of the lower surfaces of the spring strut would have needed to occur immediately before the accident flight to detect it, and even then, visibility would have been poor. The small fatigue cracks at the origin areas were concealed by washers and were not visually detectable.

Safety Recommendations

The Safety Board had previously issued recommendations regarding this issue. The Federal Aviation Administration reported that the visual inspections specified in maintenance manuals were adequate to detect cracks in the main landing gear struts and that additional airworthiness action was not warranted. On March 25, 2002, the NTSB responded, stating that it continued to believe that visual inspection alone would not detect cracks in the Cessna main landing gear spring struts. However, the Safety Board acknowledged that statistical evidence did not warrant issuance of airworthiness directives at that time as called for in its recommendation. The safety recommendation was subsequently classified as "Closed-Reconsidered."

Probable cause

The fracture occurred due to fatigue cracks that emanated from the chamfer areas at two bolt hole locations on the inboard side of the strut.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20070608X00699. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.