NTSB Identification: ERA11IA172
14 CFR Part 91: General Aviation
Incident occurred Sunday, January 16, 2011 in Walterboro, SC
Probable Cause Approval Date: 02/23/2012
Aircraft: MITSUBISHI MU-2B-20, registration: N52CD
Injuries: 2 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

The pilot reported hearing a “pop” sound from the nose gear area when the gear was extended for the landing. Toward the end of the landing roll, the nose gear collapsed. A postaccident examination of the nose gear revealed that the bolt that holds the downlock drag brace joint link to the airframe structure had fractured. A metallurgical examination revealed that the bolt failed in reverse bending fatigue, which is associated with the bolt having insufficient clamping pressure (looseness). The airplane’s last required inspection was about 70 flight hours and 40 gear cycles before the nose gear collapsing, and the nose gear downlock system rigging should have been inspected at that time.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

The inadequate inspection and rigging of the nose landing gear downlock mechanism by maintenance personnel, which resulted in the failure of a bolt and the subsequent collapse of the nose gear during the landing roll.

Full narrative available

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