Cirrus SR22 N915TD incident near Scottsdale, Arizona

Probable cause

The failure of the nose landing gear due to unanticipated fatigue loads.

NTSB analysis

***This report was modified on August 1, 2018. Please see the docket for this incident to view the original report.***

While the pilot receiving instruction was landing the airplane, the main landing gear touched down first; as he was slowly lowering the nose landing gear (NLG) to the runway, he felt a "shimmy" in the NLG. Despite applying back pressure to lift the weight off the NLG, the airplane's nose slowly started falling forward, and the nosewheel collapsed.

Postincident examination of the airplane revealed that the NLG was fractured through the strut tube adjacent to the forward edge of the gusset tube attachment welds. Metallurgical testing revealed that the failure was the result of high-stress fatigue cracking due to sideways bending from one side. No mechanical or metallurgical anomalies were noted with the NLG.

After the incident, the airplane manufacturer conducted structural testing of the NLG, which revealed that shimmy events or nonstandard towing could result in cracks and the eventual separation of the NLG. As a result, the airplane manufacturer issued two service advisory letters, which outlined appropriate towing and inspection procedures. The airplane manufacturer also issued a series of service bulletins, which, in part, recommended that all NLG on the affected airplanes be inspected for cracks in the welds between the strut tube and the gusset tubes and that postshimmy inspections also be conducted to look for cracks in this area. Additionally, the airplane manufacturer updated the design of the NLG to increase the strength of the strut tube.

Text from the NTSB. Open the NTSB docket for WPR15IA252 for the full record.