Accident Summary
On October 3, 2009, at 0900 mountain standard time, a Cessna 172A, registration N7810T, was landing at Payson Airport, Payson, Arizona, when the nose landing gear fork separated during touchdown. The student pilot, who was also the registered owner, lost control of the airplane. The pilot was not injured, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan was filed. The flight had departed from Payson Airport at approximately 0800.
Aircraft and Pilot Information
The aircraft involved was a Cessna 172A, serial number not specified. The pilot was a student pilot operating under 14 Code of Federal Regulations Part 91. The pilot reported that this was his second or third landing of the flight.
Landing and Damage
As the airplane touched down, the nose landing gear fork separated, causing the airplane to veer left and impact the runway. The right wing sustained substantial damage. The student pilot stated that the previous owner had frequently landed on unimproved terrain.
Examination of Nose Gear
The nose landing gear fork was examined by the National Transportation Safety Board Materials Laboratory. The part was made of 2014 series aluminum. The fracture surface exhibited two distinct regions: a flat area with evidence of corrosion, consistent with slow crack growth over time, and slanted irregular surfaces with a shiny crystalline appearance. Scanning electron microscope examination of the corrosion crack revealed no features consistent with fatigue. Crack propagation appeared intergranular with branching into adjacent grains. Although no single origin was identified, the crack appeared to have started from a point on the surface of the bolt hole bore and propagated upward and outward. It could not be determined if the crack would have been visible during a routine inspection.
Probable Cause
The investigation did not state a probable cause.