NTSB Identification: WPR10LA004
14 CFR Part 91: General Aviation
Accident occurred Saturday, October 03, 2009 in Payson, AZ
Probable Cause Approval Date: 12/20/2010
Aircraft: CESSNA 172A, registration: N7810T
Injuries: 1 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot reported that, as the airplane touched down, the nose gear separated and the airplane veered to the left before coming to rest on the runway. During the event the right wing was substantially damaged. Postaccident examination of the separated nose landing gear fork indicated that the alloy used for forging the part was 2014 series aluminum, which is susceptible to stress corrosion cracking (SCC) given the proper environment and a continuous stress state. A Safety Board metallurgist concluded that the fracture characteristics were consistent with SCC, with slow crack growth over time. The crack appeared to have originated from a point on the surface of the bolt hole bore and propagated upwards and outwards. The last annual inspection of the airplane was conducted about two weeks prior to the accident, although the investigation was unable to determine if the crack would have been visible to the unaided eye during a routine inspection.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The stress corrosion cracking of the nose gear landing fork, which resulted in the fork's failure during landing. Full narrative available
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